2.0 MicroMODEL SURFACE MODELING

2.1 Introduction

The Surface Modeling Sub-Menu appears below:

  1. Return To Main Menu
  2. Command Shell
  3. Digitize and Display Surface Data (Menu)
  4. Prepare Surface or Thickness Data
  5. Display Prepared Surface or Thickness Data Points
  6. Variogram Analysis (Menu)
  7. Surface or Thickness Modeling Presort
  8. Surface or Thickness Modeling
  9. Graphical Display of Surface or Thickness(Menu)
  10. Surface or Thickness File Manipulation
  11. Create Rock Model from Surface Models
  12. Change Name of Surface (Cone) Model
  13. Change Name of Thickness Model
  14. Create Triangulation Model of Surface or Thickness
  15. Clean-Up Directory

The purpose of the Surface Modeling Module is to create two-dimensional, gridded elevation or thickness models. The most common use is in creating a gridded elevation model of the deposit topography. The surfaces or thickness models are stored as 2-D cell value files. Programs are available which allow the user to build the grids with various modeling methods, and to display them in several ways. See Volume I, Sections 3.0 and 4.0 for surface modeling conventions and methodology.

2.2 Command Shell

This menu choice enables the user to invoke commands and run external programs without exiting MicroMODEL. Please refer to section 1.2.

2.3 Digitize and Display Surface or Thickness Data (Menu)

2.3.1 Introduction

This submenu enables the user to capture and display surface elevation or thickness data. All data captured in the Surface Modeling menu should be thought of as point elevations (or thicknesses) with northing, easting, and elevation coordinates. The submenu appears as:

  1. Return To Submenu
  2. Command Shell
  3. Set Digitizer Button Labels - Enable/Verify V-TAB
  4. Digitize Data in Plan View
  5. Plot Digitized Data in Plan View
  6. Plot Digitized Data in Perspective

Options 1 - 2 perform as in all menus. Option 3 allows the user to define the labels for each button on the digitizer puck, and to verify that the Virtual Tablet driver is working. Option 4 allows the user to digitize coordinates using a digitizing tablet. Options 5 and 6 plot the digitized data in plan view and perspective.

2.3.2 Command Shell

This menu choice enables the user to invoke commands and run external programs without exiting MicroMODEL. Refer to Section 1.2 for details.

2.3.3 Set Digitizer Button Labels - Enable/Verify V-TAB

This option allows the user to enter the button labels for the digitizing tablet that will be used with MicroMODEL. This program MUST be run before the user attempts to digitize topography or rock zones. Once this program has been successfully run, the user need not run it again, unless the digitizer puck configuration changes.

Note: MicroMODEL (and PolyMap) now use the Virtual Tablet driver. The Virtual Tablet driver must be installed prior to using the digitizing program. If you do not yet have the Virtual Tablet driver installed, you must do so before using MicroMODEL, or an error will be issued.

In theory, MicroMODEL should be compatible with any digitizing tablet that is supported by the Virtual Tablet driver. Popular brands such as Calcomp, GTCO, and SummaGraphics are all compatible with MicroMODEL.

This is a multiple answer set program, so the user is first asked to select the answer set number. The ANSWER SET NAME is entered.

Next, the user enters a list of BUTTON CODES (labels). The button codes are the actual label of the button as it appears on the digitizer puck.

The user should check the checkbox which enables the Virtual Tablet interface. This checkbox is provided so that the user can disable the Virtual Tablet callup procedure, if at a later time the digitizer is disconnected for some reason. If there is no digitizing tablet hooked up, and this box is checked, then each time MicroMODEL is started, an error message is issued.

Finally, the user should press the "Test and Exit" button. This calls up another screen where the user can verify the operation of the digitizer. as the puck is moved on the table, the X-Y coordinates of of the puck should echo in the two text fields near the bottom of the screen. As each button on the puck is pushed, the associated button on the screen should become enabled.

2.3.4 Digitize Data in Plan View

This option allows the user to digitize point elevations or contours with a digitizing tablet, from existing property maps. The point elevations can be entered off of contour maps or drawings of surveyed points.

The digitized point elevation data which are used to create the surface (or thickness) model are captured as global northings, eastings, and elevations. The digitizer captures the northings and eastings. The elevation (or thickness) for each group of iso-elevation points is specified by the user from the computer keyboard.

Before running this program, the user must define the digitizer buttons and enable/verify the Virtual Tablet (2.3.2). To digitize a map containing elevation data, the user should attach the map to the digitizer table with the global grid of the map skewed slightly to the table edge. If the digitizer table grid and map global grid are exactly parallel, it is not possible to digitize without generating conversion errors caused by precision losses in the computer. Remember, always place the map on the digitizer at a "crooked" angle. A "tilt" of 15 degrees or more is sufficient.

Once the digitizer has been set up, and the map placed on the tablet, the user can run the Digitize Surface Data in Plan View program. This is a multiple answer set program, and the user must enter the ANSWER SET NAME.

Next, the user enters the DIGITIZED DATA FILE NAME. The user can either APPEND to this file, or OVERWRITE the contents. If the user opts to OVERWRITE the file, and the file already exists, then a warning is displayed.

On the second input screen, the user is instructed to enter the lower left and upper right corner setup coordinates. These are the coordinates of any two corner points of a rectangle that is parallel to world coordinates.

When the user is ready, he should press the "Digitize Setup Points" Button. Then, the user is prompted to digitize, in order, the lower left, upper left, upper right, and lower right corner coordinates of the rectangle. As these points are being digitized, the program echoes their location, in digitizer coordinates, in the lower right corner of the screen.

When all four setup points have been digitized, the user is allowed to digitize one or more check points from the map. The test point coordinates are echoed, this time in world coordinates, in the lower right corner of the screen. If the test coordinates look good, then the user can press the "OK" button to continue with digitizing. Otherwise, the user should press the "Digitize Setup Points" button again to retry.

Once the user has successfully setup for digitizing, topography can be entered. Note that user prompts are displayed in the title bar of the program window.

Most digitizer buttons can be used to enter digitized points. However, certain buttons, which are listed along the right hand side of the screen, can be pressed to execute commands. For example, for the Calcomp Drawing Board, button 1 can be pressed to end the current line. The mouse can also be used at any time to digitize a point. However, the point digitized must fall somewhere within the limits of the current display.

If the user desires to have audio feedback for each point as it is digitized, the "Turn on Echo Bell" check box at the top right of the screen can be checked. Note that the sound card must be enabled, and the volume turned up in order for this to work.

The user must enter the elevation of the topo contour that will be digitized in the entry field at the top right of the screen. This elevation can be changed at any time up the the point that the user presses the "END Current Line" button. Once several contours have been digitized in a logical order, for example, 10 feet, 20 feet; the user can press the "Change ELEV Last Delta" button to increment the elevation in the same progression. For this example, the next progression would be 30 feet.

If the user makes a mistake while digitizing a line, the "CANCEL Line/Zoom" button will cancel that line. If the user finds he has made a digitizing error after pressing the "END Current Line" button, the user can still delete the erroneous line by pressing the "DELETE Last Polyline" Button.

The user can control the area that is viewed on the screen with the "ZOOM View" command. This button is pressed, and then the user must digitize the lower left and upper right corners of the new view area. The "CANCEL Line/Zoom" button can be used to cancel the zoom function.

The user may move a map, if necessary, during a digitizing session by pressing the "New Map Setup"

button. This command simply returns the user to the map setup stage of the program. The user enters new setup points, digitizes the corner points, and then continues with more digitizing.

When the user has finished digitizing, then the "Exit and Save" button is pressed. This exits the program and saves all digitized data that was entered during the session and returns the user to the MicroMODEL main menu.

If, for some reason, the user feels that the entire digitizing session should be canceled, then the "Exit and CANCEL" button should be pressed. The user is asked to confirm this, since considerable effort could be wasted if this button was accidentally pressed.

2.3.5 Plot Digitized Data in Plan View

This option allows the user to plot the point elevation data that was previously digitized, or converted from another source (DXF). The plotted output can be used to verify that the elevation points have been entered correctly.

The LOCAL GRID can be plotted over the plot according to three LOCAL GRID PLOTTING OPTIONS. Refer to Section 1.8 and to Chapter 11, Plotting, for details.

If the LOCAL GRID is to be plotted, the user must specify a PEN COLOR for the GRID NUMBERS, either a LOCAL GRID LINE PEN COLOR or a TIC MARK PEN COLOR, and a PERIMETER LINE PEN COLOR. The character size for the grid numbers is a fraction of the cell dimension, and the character size of the northings and eastings is the same as specified for the contour interval labels.

The GLOBAL GRID can be displayed on the finished plot. Refer to section 1.8 and Chapter 11, Plotting, for details.

If the GLOBAL GRID is to be plotted, the user must specify a GLOBAL GRID INTERVAL in the project units (Feet or Meters) and a PEN COLOR for the GLOBAL GRID LINES. The character size is the same as specified earlier.

Row and Column Clipping allows the user to plot a partial section (window) of the model area. The user defines this window with STARTING and STOPPING COLUMNS and ROWS as prompted by MicroMODEL. For further explanation on ROW and COLUMN CLIPPING, see Chapter 11, Plotting.

The LABEL CHARACTER SIZE of the elevations is specified as a fraction of the row dimension. A character size of 0.25 results in plotted characters that have a height which occupies one quarter of the row dimension. See Volume I, Section 6.3.8 for more information on selecting character sizes.

Since it is possible to contour on fractions, the user can structure the output format by specifying the NUMBER OF CHARACTERS BEHIND THE DECIMAL when prompted. If the user does not want to have any characters behind the decimal point and also does not wish to display the decimal point, a -1 should be entered. Refer to section 1.8 for details.

The CONTOUR LABEL INTERVAL controls how often each contour is labeled. This distance is in FEET (English Units) or METERS (Metric Units). For example, entering 500 for a project in English Units would cause the contour to be labeled every 500 feet.

The user selects the PEN COLOR for Digitized Lines.

There is an option to plot only a range of contours, which is Minimum Level and Maximum Level Number. This is convenient when plotting a contour on a single bench (level), or range of benches.

The source of the digitized data file must be selected. The default is from ASCII file POLY.CNT. The user may elect to choose a different ASCII file by pressing the "Access *.CNT Files" button. This will bring up a standard file selection dialog. If the user wishes to display digitized data directly from a PolyMap map, then the "Access PolyMap" button is pressed, and the user selects the PolyMap directory and then selects the individual map name to display.

The TITLE BLOCK parameters are set after all program parameters have been set. For a complete discussion of the TITLE BLOCK QUESTIONS, see chapter 11, Plotting.

The Digitized Data in Plan View Plotting program produces a scaled plot that can be output at any user specified map scale (see Volume I, Section 6.3.7). The SCALE OF THE PLOT determines the plot size in feet/inch or meters/meter. For further explanation on SCALE OF PLOTS, see Chapter 11, Plotting.

2.3.6 Plot Digitized Data in Perspective

This option allows the user to produce a three-dimensional plot of the previously digitized elevation data for display purposes only. The perspective plot can be viewed from any point in space that lies above the grid. Several other options are available to produce the desired output.

All lines that are to be displayed, both pit lines (if required) and topographic contours, must be digitized. Only the digitized surface data is plotted.

Two types of views can be plotted of the digitized data in the Perspective Viewing option. PERSPECTIVE VIEW converges some lines at a distant point to generate an appearance of depth. ISOMETRIC VIEW plots all lines relative to the local grid so there is not an appearance of depth due to converging lines.

VERTICAL EXAGGERATION enables the user to enter a factor that scales all values to generate more (factor > 1) or less (factor < 1) relief. The program can also choose a vertical exaggeration factor automatically.

The view point is defined by its DISTANCE TO EYE. The user can enter either a distance in the project units or specify "A" (Automatic distance) and the system chooses an appropriate distance.

Depending on the orientation of the viewpoint, the fishnet may contain lines that are "hidden" behind lines closer to the view point. The user can suppress the plotting of hidden lines by responding "Y"es to the HIDDEN LINE REMOVAL question. The hidden line option takes slightly longer to execute but usually produces clearer results.

Row and Column Clipping allows the user to plot a partial section (window) of the model area. The user defines this window with STARTING and STOPPING COLUMNS and ROWS as prompted by MicroMODEL. For further explanation on ROW and COLUMN CLIPPING, see Chapter 11, Plotting.

A point is defined in space, from which the user views the grid. This viewing point is specified by the VIEW DIRECTION ANGLE (an azimuth clockwise from North) from the viewer's eye to the grid. Generally, raised contours have a better appearance if the grid is viewed diagonally. Next, the VIEW DIP DIRECTION is entered (+90 degrees is looking vertically down). Generally, a plunge of 30 to 60 degrees yields the best results.

The TITLE BLOCK parameters are set after all program parameters have been set. For a complete discussion of the TITLE BLOCK QUESTIONS, see chapter 11, Plotting.

The Plot Digitized Data in Perspective option produces a scaled plot that can be output at any user specified map scale (see Volume I, Section 6.3.7). The SCALE OF THE PLOT determines the plot size in feet/inch or meters/meter. For further explanation on SCALE OF PLOTS, see Chapter 11, Plotting.

2.4 Prepare Surface or Thickness Data

There are four types of data that can be used to model topography or thicknesses with MicroMODEL. The first is the drill hole collar elevations or downhole locations. The second type of surface data is point elevations that have been captured in the Digitizing Menu (Section 2.3). The third type of data is topography contours stored in PolyMap maps, and the fourth type of data is plain text (ASCII) X-Y-Z data files.

The user must tell the program which type of data is being prepared (Surface or Thickness), and which label (model number) is being prepared. These are selected in the upper right corner of the first input screen. For all surfaces or thicknesses except starting topography, the user must also enter a description of the model. This description is used later by other programs when the surface or thickness is selected.

The Prepare Surface or Thickness Data option takes any combination of the four types of data and prepares the data for input to the presorting program. Up to three separate POLY.CNT style files (MicroMODEL digitized data) can be used. Up to three PolyMap topography maps can be used. Only one X-Y-Z data file can be used.

After the raw surface data is prepared by this program, it is written to a temporary file which is subsequently used as input to the presorting and modeling programs. This preparation step prevents corruption of the original surface data and speeds the surface or thickness modeling process.

The user selects which types of data will be used by checking appropriate check boxes. For digitized data, the POLY.CNT style file name must be specified. For PolyMap maps, the actual map name must be selected. For X-Y-Z data, the data file name must be selected.

The user can filter the data in order to reduce the amount of points that are actually extracted. First, a CONTOUR INTERVAL and CONTOUR OFFSET can be entered. For example, a contour interval of 10.0 feet with an offset of 5.0 feet will extract contours at 5, 15, 25, 35, etc. feet.

Also, the user can limit data points to those which are inside one or more fault zones, or that fall inside a simple polygon that is defined by four corner points. Any points that fall outside the limits will be discarded. A radio button is selected to indicate which of these options is to be used. For no limits, the user selects the "No Limit" radio button.

If fault zone or simple polygon limits are selected, the user may choose which of the four data types will be affected by these limits. There are four check boxes located beneath the polygon limit radio buttons. For each data type that should be filtered by the polygons, select the check box. Any combination can be selected. For example, it is possible to apply the polygon or fault zone limits to Drillhole Collars and POLY.CNT data files, but not to PolyMap Maps or X-Y-Z data files.

Once the user has specified the type(s) of data to use, the system searches through each type of input elevation data. A temporary file containing the coordinates for each elevation data point is created. This file is used as the input for all presorting and modeling runs until a different set of data is prepared, which then overwrites the existing prepared data.

2.5 Display Prepared Surface or Thickness Points

This option allows the user to display the location and value of each data point that was prepared by "Prepare Surface or Thickness Data." The user must specify which model type, and which surface or thickness is to be displayed.

The 64-character ANSWER SET NAME is simply used to identify this set of answers.

The LOCAL GRID can be plotted over the plot according to three LOCAL GRID PLOTTING OPTIONS.

  1. Do NOT plot a local grid
  2. Plot local tic marks
  3. Plot a full local grid

If the LOCAL GRID is to be plotted, the user must specify a PEN COLOR for the GRID NUMBERS and either a LOCAL GRID LINE PEN COLOR or a TIC MARK PEN COLOR and PERIMETER LINE PEN COLOR. The character size for the grid numbers is a fraction of the cell dimension, and the character size of the Northings and Eastings is the same as for the drill hole identification information. For further explanation on LOCAL GRID OPTIONS, see chapter 11, Plotting.

The GLOBAL GRID can be displayed on the finished plot. Select the appropriate check box. Otherwise, leave the box unselected.

If the GLOBAL GRID is to be plotted, the user must specify a GLOBAL GRID INTERVAL in the project units (Feet or Meters) and a PEN COLOR for the GLOBAL GRID LINES. The character size is the same as specified earlier. For explanation on GLOBAL GRID OPTIONS, see chapter 11, Plotting.

Row and Column Clipping allows the user to plot a partial section (window) of the model area. The user defines this window with STARTING and ENDING ROWS and COLUMNS as prompted by MicroMODEL. For further explanation on ROW and COLUMN CLIPPING, see chapter 11, Plotting.

Each prepared sample location within the plot area is marked with a "+" symbol. The user may optionally display the data value (elevation or thickness). The color of the location marker and the data value are specified by the user. To display the data values, the user must check to appropriate box at the top of the second input screen. The number of digits following the decimal can be selected on this screen. Note that if the user is displaying prepared data from digitized contours, the display will become very cluttered if the data values are displayed in this case.

The CHARACTER SIZE is specified by the user as a fraction of the row dimension. A character size of 0.25 results in plotted characters that have a height which occupies one quarter of the row dimension. See Volume I, Section 6.3.8 for more information on selecting character sizes. For further explanation on CHARACTER SIZE, see chapter 11, Plotting.

The user selects a PEN COLOR for the data location mark, GLOBAL GRID LINES, LOCAL GRID INTERNAL LINES, LOCAL GRID PERIMETER LINES, LOCAL GRID NUMBERS, and LOCAL GRID TIC MARKS.

The TITLE BLOCK parameters are set after all program parameters have been set. For a complete discussion of the TITLE BLOCK QUESTIONS, see chapter 11, Plotting.

The Prepared Surface or Thickness Data Plotting program produces a scaled plot that can be output at any user specified map scale (see Volume I, Section 6.3.7). The SCALE OF THE PLOT determines the plot size in feet/inch or meters/meter. For further explanation on SCALE OF PLOTS, see chapter 11, Plotting.

2.6 Variogram Analysis (Menu)

2.6.1 Introduction

The options available in the Variogram Analysis submenu allow the user to calculate and plot the variogram for the prepared surface or thickness data. Calculation of the variogram and obtaining a variogram model is mandatory prior to using the surface or thickness modeling programs, only if the user wishes to use kriging to create the surface or thickness model. The analysis of the variogram is also useful in selecting appropriate search distances and other modeling parameters for both Inverse Distance to a Power (IDP) and kriging.

The programs in this submenu enable the user to perform variogram analysis on the prepared surface data. This submodule appears as:

  1. Return To Submenu
  2. Command Shell
  3. Calculate and Print Variogram
  4. Print Variogram/Model
  5. Plot Variogram/Model

Options 1 - 2 perform as in all menus. Option 3 calculates the experimental variogram, while options 4 and 5 plot the experimental variogram and/or a fitted theoretical variogram model.

Some of the terminology used in the Variogram and grid modeling programs may be new to users unfamiliar with geostatistical methods. Although MicroMODEL was designed to be used by users without prior modeling experience, a basic understanding of geostatistics is recommended before proceeding with variogram analysis and kriging.

2.6.2 Command Shell

This menu choice enables the user to invoke commands and run external programs without exiting MicroMODEL. Refer to Section 1.2 for details.

2.6.3 Calculate and Print Variogram

This option allows the user to calculate experimental variograms for 1 to 9 directions per run with user specified directions, tolerances, and lag distances. The resulting variogram data is printed to the screen or printer in table form. This experimental variogram data is saved for analysis in the next two options, Print and Plot the Variogram/Model.

The ANSWER SET NAME identifies this set of Variogram answers.

The user must specify which type of data, surface or thickness, to use. The model number is also specified. The type of data is selected via two radio buttons, and the model number is then selected from a pulldown menu.

If needed, the user can specify that LOG TRANSFORMATIONS be used. The program then calculates the variogram based on the natural logarithms of the prepared surface data. If LOG TRANSFORMATIONS is selected, then a third parameter constant can be added to all values.

The user can also control the data used by the Variogram program by requesting to use CUTOFF GRADES (values) on the input data. If cutoff values are used, data outside the range specified by the MINIMUM and MAXIMUM cutoff grades is ignored. Selection of data relative to the cutoff range is made before the data is logarithmically transformed.

The user can calculate up to 9 variograms for each run as specified by the NUMBER OF VARIOGRAMS TO CALCULATE.

For each variogram, the TITLE is used to identify that variogram in the subsequent printing and plotting programs.

For each variogram direction, the user enters the AZIMUTH OF THE SEMIVARIOGRAM. This is an azimuth measurement in degrees clockwise from North. The WINDOW ANGLE IN THE PRIMARY SEARCH PLANE is the angle in degrees from each side of the axis in which data is included in the calculations. A window angle of 90 degrees results in an average, non-directional, variogram.

The TOLERANCE BAND IN THE PRIMARY SEARCH PLANE is used to reach additional data points, by expanding the "window" by a constant offset from the line segments that make up the legs of the window angle. Figure 2.1 illustrates the use of the window angle and tolerance band.

The CLASS SIZE or LAG DISTANCE is the distance at which data is paired. The extent of the variogram is (# of classes x LAG DISTANCE). Generally, a first pass lag distance is: (diagonal model distance) / 25.

MicroMODEL allows up to 25 CLASS or LAG INTERVALS. The user can select from 1 to 25 class intervals for each variogram direction.

2.6.4 Print Variogram/Model

The experimental variogram is calculated from the input data by the program described in Section 2.6.3, Calculate and Print Variogram. The variogram model is a user specified mathematical function that represents the experimental variogram.

This option allows the user to quickly display any or all of the experimental variograms and/or a user specified variogram models on the printer. The Print Variogram program first prompts the user to select the answer set number for the "Calculate and Print Variogram" Program. This program can print any of the previously run sets of variograms.

The first input screen allows the user to enter an ANSWER SET NAME to identify this set of answers. There is also one check button on the initial screen for each variogram that was calculated in section 2.6.3. The user should check the check button of each variogram he wishes to display.

For each variogram selected (checked) in the first screen, the user must select scaling factors, define variogram models, and elect whether or not to plot the variance line.

The user can select AUTOMATIC scaling for both the X and Y axis of the variogram plot, or can elect to use a fixed value in either direction. There are eight vertical intervals and ten horizontal intervals. Thus, a horizontal interval of 10 feet would plot the variogram from 0 to 100 feet. A vertical interval of 0.1 units would plot the variogram from 0 to 0.8 units. Automatic scaling is a good choice for the first run through this program. Fixed values allow the user to plot every variogram using the same scaling factors, making it easier to compare one variogram against another.

The user can choose to PRINT THE VARIANCE LINE for the variogram by choosing the <YES> choice button.

This program always plots the experimental variogram. To add a model or models, the user must select the NUMBER OF NESTED MODELS. For example, the user may wish to nest one linear and one spherical model. In this case, enter "2" for the NUMBER OF NESTED MODELS. The program prompts the user for the NUGGET VALUE of the variogram model, and then for each nested structure, select the MODEL TYPE, MODEL RANGE, and MODEL SILL. Supported variogram model types are spherical, linear, exponential, and gaussian. See Volume I, Section 3.5 for a discussion of MicroMODEL's variogram model conventions.

The RUNTIME TITLE is a title that appears with the project title on the output. The runtime title should contain information that is specific to this run, such as date, operator, important input parameters, etc. This input serves no other purpose but to identify each run.

2.6.5 Plot the Variogram/Model

The experimental variogram is calculated from the input data by the program described in Section 2.6.3, Calculate and Print Variogram. The variogram model is a user specified mathematical function that represents the experimental variogram.

This option allows the user to quickly display any or all of the experimental variograms and/or a user specified variogram models on the screen or plotter.

This program first prompts the user to choose the answer set number for the "Calculate and Print Variogram" program. The Plot Variogram Program can plot any of the previously calculated variograms.

The first input screen allows the user to enter an ANSWER SET NAME to identify this set of answers. There is also one check button on the initial screen for each variogram that was calculated in section 2.6.3. The user should check the check button of each variogram he wishes to display.

For each variogram selected (checked) in the first screen, the user must select scaling factors, define variogram models, and elect whether or not to plot the variance line.

The user can select AUTOMATIC scaling for both the X and Y axis of the variogram plot, or can elect to use a fixed value in either direction. There are eight vertical intervals and ten horizontal intervals. Thus, a horizontal interval of 10 feet would plot the variogram from 0 to 100 feet. A vertical interval of 0.1 units would plot the variogram from 0 to 0.8 units. Automatic scaling is a good choice for the first run through this program. Fixed values allow the user to plot every variogram using the same scaling factors, making it easier to compare one variogram against another.

The user can choose to PRINT THE VARIANCE LINE for the variogram by choosing the <YES> choice button.

This program always plots the experimental variogram. To add a model or models, the user must select the NUMBER OF NESTED MODELS. For example, the user may wish to nest one linear and one spherical model. In this case, enter "2" for the NUMBER OF NESTED MODELS. The program prompts the user for the NUGGET VALUE of the variogram model, and then for each nested structure, select the MODEL TYPE, MODEL RANGE, and MODEL SILL. Supported variogram model types are spherical, linear, exponential, and gaussian. See Volume I, Section 3.5 for a discussion of MicroMODEL's variogram model conventions.

The experimental variogram is calculated from the input data by the program described in Section 2.6.3, Calculate and Print Variogram. The variogram model is a user specified mathematical function that represents the experimental variogram.

This option allows the user to display the experimental variogram and/or a user specified variogram model as an unscaled plot.

This allows the user to skip a variogram direction, or to plot the variogram model for a given set of directions.

If the user elects to PLOT THE EXPERIMENTAL VARIOGRAM PLUS A MODEL, the program prompts the user for the NUGGET VALUE of the variogram model, and then for the number of nested structures to use. There can be up to nine nested structures for each direction. The user is then prompted for a MODEL TYPE, MODEL RANGE, and a MODEL SILL for each nested structure. Supported variogram model types are spherical, linear, exponential, and gaussian. See Volume I, Section 3.5 for a discussion of MicroMODEL's variogram model conventions.

The user can choose to plot a variance line for each direction of the experimental variogram. He is also prompted to enter a distance between labeled lag intervals (X axis), and labeled variance intervals (Y axis). By entering an "A" for automatic scaling, the user can force the program to select these distances.

Please note that each of these options is requested for each direction used during the calculation of the experimental variogram.

The BOTTOM TITLE is a title that appears at the bottom of the variogram plot.

If the user elects to PLOT THE EXPERIMENTAL VARIOGRAM AND A MODEL, the user must select a PEN COLOR for the Model Variogram. The PEN COLOR is restricted by the installed plotting device.

The user may elect to plot the number of sample pairs that were used to calculate each experimental variogram point. The CHARACTER SIZE FOR PLOTTING NUMBER OF DATA PAIRS should be set at a value greater than zero, but less than 0.5. Setting this value to zero suppresses the plotting of these values. This character size is expressed in inches, rather than as a percentage of row size. The PEN COLOR for these data pair labels can be set to anything the user desires.

The user may select PEN COLORS for the PLOT BOX, the TIC MARKS, the SCALE LABELS, the SCALE NUMBERS, and the PLOT KEY or explanation. The user may also enter a DRAWING TITLE, and a PROJECT TITLE with the PEN COLOR to plot the titles. Again, all PEN COLORS are restricted by the installed plotting device.

If the user desires to connect the data points of the experimental variogram, then a PEN COLOR other than 0 (Do not plot) should be chosen.

The Variogram Plotting program produces an unscaled plot (see Volume I, Section 6.3.9). A PLOT SCALE of "R" produces a standard report size, 8.5in x 11in (215mm x 280mm), plot. The plotting program produces one plot for each variogram direction. For further explanation on SCALE OF PLOTS, see Chapter 11, Plotting.

2.7 Surface or Thickness Modeling Presort

The Surface or Thickness Modeling option (Section 2.8) assigns an values to each cell of the surface or thickness grid according to user specified constraints. Before the user can proceed to modeling, the elevation or thickness data for the deposit must first be prepared (Section 2.4) and presorted.

The Surface/Thickness Modeling Presort option presorts data for each grid cell center within user specified bounds. The advantage of separating the presorting and modeling routines is, that once presorting is accomplished, several modeling runs can be made on the same presorted file with a minimum of computer time.

The user must select which type of model (surface or thickness), and which label to presort for. The presort data file that is created by this program is unique to each combination of model type and model label. The user does not need to rerun the presort for surface data for each surface modeling run unless the data search (presort) parameters are changed.

It is not necessary to presort the surface data for each surface modeling run unless the data search (presort) parameters are changed.

During surface/thickness grid modeling, it is possible to have unestimated cells due to restrictive search (presort) parameters. For best results during Pit Generation and Reserves Evaluation, it is required that presort parameters be selected such that all cells are estimated in the surface model. If unestimated cell values cannot be avoided, these unestimated cells should be assigned approximate values with the Grid Editing program in the File Management module.

NOTE: The Pit Generation programs (Module 6) do not work correctly if any missing (unestimated) topography values exist.

The ANSWER SET NAME is used to identify this set of answers, and also is a title that appears with the project title on the output. The runtime title should contain information that is specific to this run, such as date, operator, important input parameters, etc. This input serves no other purpose but to identify each run.

There are two search options on the surface/thickness modeling presort. The first search option is FIND CLOSEST POINTS, which searches for the nearest user specified number of data points regardless of the locations of the data points relative to the cell center as shown in Figure 2.1. With this option, it is possible to find points from a clustered location which can bias modeling results. Next, the system requests the MAXIMUM NUMBER OF POINTS (32 max) to be used to estimate each known cell center. Modeling runtimes increase as the maximum number of points increases. Generally, 16 to 24 points is adequate.

                FIGURE 2.1
                CLOSEST POINT SEARCH
                Maximum Search Radius = 250 Feet
                Maximum Number of Points = 12

The second search option is OCTANT SEARCH. With this option, a user specified maximum number of points is searched for in each octant (45 degree sector) as illustrated in Figure 2.2.

                FIGURE 2.2
                OCTANT SEARCH
                Maximum Search Radius = 250 Feet
                Maximum Points Per Octant = 3

                ANISOTROPIC SEARCH
                PRIMARY AXIS LENGTH = 250 Feet
                SECONDARY AXIS LENGTH = 200 Feet
                ROTATION ANGLE = 60 Degrees
                Total Points Found = 17

The MAXIMUM NUMBER OF POINTS PER OCTANT, N (4max), instructs the program to find the closest N points within each sector of the search ellipse. Octant search is generally the best method to use with surface data as it finds data surrounding the cell center, as opposed to taking all data in isolated clusters.

A search ellipse is used for surface/thickness data that has a definite trend such as a ridge or trench. If the data demonstrates a trend it is ANISOTROPIC (i.e., not ISOTROPIC). Surface data that does not show a trend is ISOTROPIC and the search ellipse defaults to a circle with a radius equal to the maximum search radius.

The user defines the maximum distance from the cell center for which data are used in the estimation. This distance is the SEARCH RANGE. It is also called the SEARCH RADIUS. The maximum search radius is the longest radius of the search ellipse.

For ANISOTROPIC DATA, the search ellipse is defined by its orientation and size as shown in Figure 2.3. The orientation is specified by the ROTATION ANGLE (azimuth) from North to the Primary (generally the longest) axis. The size of the ellipse is specified by the maximum search range (radius) and the ratio of the secondary axis radius to the primary axis radius. This relationship is described below:

                FIGURE 2.3
                TWO DIMENSIONAL ELLIPSE OF ANISOTROPY
                SEARCH RADIUS = 100 m
                PRIMARY AXIS LENGTH RATIO: 100      
                SECONDARY AXIS LENGTH RATIO: 50
                ROTATION ANGLE: 60 Degrees
    PRIMARY AXIS RADIUS = MAXIMUM SEARCH RADIUS

    AXES RATIO = (SECONDARY AXIS RADIUS)/(PRIMARY AXIS RADIUS)

    SECONDARY AXIS RADIUS = (AXES RATIO) x (MAXIMUM SEARCH RADIUS)

The program prompts the user for the LENGTH OF THE PRIMARY AND SECONDARY AXES. These "lengths" can be expressed in any consistent units the user chooses, such as axes lengths, axes radii, percents, ratios, etc. The search range (radius) ultimately determines the actual size of the ellipse. The axes "lengths" just describe the relative size of the primary and secondary axis radii (ellipse shape). See Volume I, Section 3.8 for further discussion of ellipse conventions.

It is possible to model a rectangular portion of the grid. This is referred to as submodeling. The rectangular area is defined by the STARTING and STOPPING, ROWS and COLUMNS. Only cells that are located within this rectangle are presorted and modeled. This feature is useful to submodel portions of the grid under different parameters due to significantly different surface or thickness data. Cells outside of the submodeled area remain unchanged.

Upon completion of the Surface/Thickness Modeling Presort, the user can proceed to Surface or Thickness Modeling and create or modify the current grid.

2.8 Surface or Thickness Modeling

This option allows the user to interpolate cell elevations into the surface or thickness model according to user specified parameters. The input data for this program is contained in the presorted data file created by the previous option, Surface or Thickness Modeling Presort (Section 2.7).

The user must select which model type (surface or thickness), and which label to model. For modeling original surface topography, the model type is surface, and the label number is zero (0).

The first time this program is run, a background grid of unestimated cell values (-999.99) is created for the data grid. This background grid is then updated with the interpolated cell values by the Surface or Thickness Modeling program. This updating may be an overwriting of the entire grid, or an overwriting of only a portion of the grid because of submodel clipping.

Two modeling options are available to the user, KRIGING and INVERSE DISTANCE TO A POWER (IDP). Next to the IDP choice button is the field for entering the POWER OF INTERPOLATION. A power of 1.0 represents linear interpolation. A power of 5.0 approaches a polygonal estimation.

The user may specify either POINT or BLOCK ESTIMATION. In POINT ESTIMATION, one elevation interpolation is made to the center of each cell that is to be estimated. BLOCK ESTIMATION tends to produce a smoother grid. With BLOCK ESTIMATION, interpolations are made to several locations in each cell, with the average of the interpolations being assigned to the cell center. If BLOCK ESTIMATION is chosen, the user must specify the DETAIL OF THE ESTIMATION. This is the number of locations in each cell at which interpolations are calculated. These locations are distributed evenly throughout the cell according to the following densities.

Block Gridding
Detail of Estimation Number of Locations
1 4
2 9
3 16
4 25
5 36

Runtimes increase proportionally with increased detail of estimation. Point Estimation or Block Estimation with a detail of 1-3 is usually adequate.

The user can request to reset all values to unestimated before this run by selecting the check box labeled "YES, Reset all values to missing". It is highly recommended that the user always choose this option for the first in a series of modeling runs. This insures that any values that were interpolated previously, say with a larger search radius, will not erroneously persist if a smaller search radius is tried.

The user can limit interpolation by specifying the MINIMUM NUMBER OF POINTS REQUIRED FOR ESTIMATION. Normally, for surface or thickness modeling, this value is set to one (1). One of the goals of surface or thickness modeling is to be sure all blocks are given a value.

For both kriging and IDP modeling options, the program asks for the NUMBER OF ANISOTROPIES to use. Choosing zero (0) anisotropies implies the data is isotropic. For data that is isotropic, the program gives points equidistant from the estimated point equal weighting in the interpolation. If the data is ANISOTROPIC, the user may enter from 1 up to 5 anisotropic weighting ellipses. Only one weighting ellipse is allowed for IDP, but one or more are allowed for kriging to take into account any zonal anisotropies that exist. MicroMODEL does not require the presorting ellipse and weighting ellipse(s) to be identical. For instance, the user may choose to presort with a circle (isotopic) and model with one or more ellipses (anisotropic).

For ANISOTROPIC DATA, the weighting ellipse is defined by its orientation and ratio of its axis "lengths" as shown in Figure 2.3. The orientation is specified by the ROTATION ANGLE (azimuth) from North clockwise to the Primary (generally largest) axis. The axis length ratio of the ellipse is specified by the ratio of the secondary axis length to the primary axis length as described below:

    AXES RATIO = (SECONDARY AXIS LENGTH)/(PRIMARY AXIS LENGTH)

The program prompts the user for the LENGTH OF THE PRIMARY and SECONDARY AXES for each anisotropy selected. These "lengths" (weighting factors) may be expressed in any consistent units the user chooses, such as axes lengths, axes radii, percents, ratios, etc. The axes "lengths" describe the relative size of the primary and secondary axes radii according to the axes ratio. Further discussion of weighting ellipse conventions can be found in Volume I, Section 3.8.

Selecting the kriging option requires the user to input the NUMBER OF VARIOGRAM MODELS TO NEST. Up to nine different variogram model structures may be nested to establish the overall variogram model.

After specifying the number of variograms to nest, the user must enter the NUGGET VALUE for the composite structure. The user must also enter the VARIOGRAM MODEL TYPE, SILL, and RANGE for each structure. If multiple anisotropies have been selected, the user must specify which ANISOTROPY should be used with each variogram model. Supported variogram model types are spherical, linear, exponential, and gaussian. See Volume I, Section 3.5 for a discussion of MicroMODEL's variogram model conventions.

The resulting grid may be displayed using any of the options in the Graphical Display Menu (Section 2.9). If the user is not satisfied with the resulting grid, the data can be presorted (if the presort parameters need to be changed) and remodeled using a different set of parameters, until the desired result is obtained.

If the 2-D data grid has been created from contoured data, it is suggested that the user overlay a contour plot of the data on top of the original, digitized data in order to check for a good grid model.

2.9 Graphical Display of Surface or Thickness

2.9.1 Introduction

This submodule allows the user to display the surface or thickness grid that has been previously created by MicroMODEL. The Graphical Display Sub-Menu is organized as follows:

  1. Return To Submenu
  2. Command Shell
  3. Printer-plot of grid values
  4. Plan View Cell plot of grid values
  5. Contour grid values
  6. Perspective view of grid values
  7. Perspective Contours

The graphic output produced by the above options are:

  1. Printer Plot (digit map - not to scale)
  2. Plan View Cell Plot showing numeric cell values (scale map)
  3. Contour Plot (scale map)
  4. Perspective View (three-dimensional fishnet - not to scale)
  5. Raised Contour View (Three-dimensional perspective contour - not to scale)

2.9.2 Command Shell

This menu choice enables the user to invoke commands and run external programs without exiting MicroMODEL. Refer to Section 1.2 for details.

2.9.3 Printer Plot of Grid Values

This option allows the user to produce a single digit map of the surface or thickness model. Each digit represents a range of elevations or thicknesses, and the key for the digits is printed below the digit map. Unestimated cells (-999.99) are indicated by a blank space. This map is generally used for quick verification only, since it is not to scale.

The ANSWER SET NAME is used to identify this set of responses. It is also used as a runtime title that appears with the project title on the output. The runtime title should contain information that is specific to this run, such as date, operator, important input parameters, etc.

The user can either specify a COMPUTER SEARCH, in which case all data values are displayed, or the user can specify a range of values to be plotted on the printer plot. This range is delimited by a MINIMUM and MAXIMUM VALUE. If the user enters a value range, cells outside of the range are specified by the appropriate "<" or ">" symbol.

The range of values, as specified by user defined minimum and maximum, or by a computer search, is divided into a user specified NUMBER OF INTERVALS. For example, if the desired range is 400 to 500 with intervals of 5 units each, the number of intervals would be:

    ((500 - 400) / 5) = 20.

With prudent selection of range values and the number of intervals, this program is very useful for quick verification and analysis of grid results.

Row and Column Clipping allows the user to plot a partial section (window) of the model area. The user defines this window with STARTING and ENDING COLUMNS and ROWS, as prompted by MicroMODEL. For further explanation on ROW and COLUMN CLIPPING, see Chapter 11, Plotting.

2.9.4 Plan View Cell Plot of Grid Values

The Plan View Cell Plotting program produces a plot that either numerically displays the assigned surface/thickness grid values, or displays color-filled rectangles, for the model. The plots can be produced at any map scale required. Several options are available which enable the user to design plots as needed.

The user has the option of using multiple pen colors, or only one pen color for the entire plot.

The ANSWER SET NAME is used to identify this set of responses.

To efficiently use the space in each cell, the user can choose the orientation of the displayed elevation values. The HORIZONTAL direction plots the lines of information "across the page" oriented with the rows. The VERTICAL direction plots the information from bottom to top.

A LOCAL GRID can be displayed according to three LOCAL GRID PLOTTING OPTIONS. For further explanation on LOCAL GRID OPTIONS, see Chapter 11, Plotting.

The GLOBAL GRID can be displayed on the finished plot at a specified GLOBAL GRID INTERVAL. The character size is the same as specified earlier. For further explanation on GLOBAL GRID OPTIONS, see Chapter 11, Plotting.

Row and Column Clipping allows the user to plot a partial section (window) of the model area. The user defines this window with STARTING and STOPPING COLUMNS and ROWS as prompted by MicroMODEL. For further explanation on ROW and COLUMN CLIPPING, see Chapter 11, Plotting.

The PEN COLOR to use for GLOBAL GRID LINES, LOCAL GRID INTERNAL LINES, LOCAL GRID PERIMETER LINES, LOCAL GRID NUMBERS, and LOCAL GRID TIC MARKS is specified in the second input screen.

Note: The number of items to plot for this program is fixed at 1, and the item to plot is always original topography.

The CHARACTER SIZE of the elevations is specified as a fraction of the row dimension. A character size of 0.25 results in plotted characters that have a height equal to one fourth the row dimension. See Volume I, Section 6.3.8 for more information on selecting character sizes.

Since it may be necessary to display surace/thickness values at a resolution smaller than whole numbers, the user can structure the output format by specifying the NUMBER OF DIGITS AFTER THE DECIMAL when prompted. If the user does not want to have any characters behind the decimal point and also does not wish to display the decimal point, a -1 should be entered. Refer to section 1.8 and to Chapter 11, Plotting.

In the Select Method for Label Pen Colors screen, the user can choose the method for plotting the model values. The user can specify that a single pen color be used. The user can specify that multiple colors be used (model values will still be displayed as printed numbers). Or, the user may elect to display the elevations in the form of colored filled rectangles. In this case, each rectangle is the same size as a model block, and the color represents a range of model values. The number of ranges, cutoffs, and pen colors are entered in the Color Ranges screen.

The Range Limits Screen allows the entry of LOWER and UPPER CUTOFF VALUES for the input model grid. They can be used to minimize plotting of unwanted cells. A cell that contains a value outside of its cutoff range is left blank.

The user selects the number of cutoffs, cutoff values, and pen colors for each range in the Color Ranges screen.

The TITLE BLOCK parameters are set after all program parameters have been set. For a complete discussion of the TITLE BLOCK QUESTIONS, see chapter 11, Plotting.

The Plan View Cell Plotting program produces a scaled plot that can be output at any user specified map scale (see Volume I, Section 6.3.7). For further explanation on SCALE OF PLOTS, see Chapter 11, Plotting.

2.9.5 Contour Grid Values

This option allows the user to produce contour maps of a surface or thickness model. The user can design the contour maps as needed by invoking a variety of plotting options. The contour plots can be produced at any map scale.

The contours can be generated at a constant interval with optional offset, or the user can specify CUSTOM intervals. To use constant contour intervals, the user selects the <NO> choice button in the Specify CUSTOM intervals choice box, and enters the CONTOUR INTERVAL. If a constant contour interval is chosen, the user can specify a CONTOUR OFFSET. This is useful for producing contours at mid-bench elevations. For example, an elevation offset of 7.5 feet would yield mid-bench contours on a project with a 15 foot bench height.

If it is necessary to specify CUSTOM intervals, the user selects the (YES) choice button in the Specify CUSTOM Intervals choice box. The number of CUSTOM intervals, and value for each CUSTOM interval, are entered in a separate screen.

LOCAL GRID PLOTTING OPTIONS. See Chapter 11, Plotting.

If the LOCAL GRID is displayed, the user must specify a PEN COLOR for the GRID NUMBERS, either a LOCAL GRID LINE PEN COLOR or a TIC MARK PEN COLOR, and a PERIMETER LINE PEN COLOR. The character size for the grid numbers is a fraction of the cell dimension, and the character size of the Northings and Eastings is the same as that specified as the contour character size.

The GLOBAL GRID can be displayed on the finished plot. If the GLOBAL GRID is to be plotted, the user must specify a GLOBAL GRID INTERVAL in the project units (Feet or Meters) and a PEN COLOR for the GLOBAL GRID LINES. The character size is the same as specified for the CONTOUR CHARACTER SIZE. For further explanation on GLOBAL GRID OPTIONS, see Chapter 11, Plotting.

Row and Column Clipping allows the user to plot a partial section (window) of the model area. The user defines this window with STARTING and ENDING COLUMNS and ROWS as prompted by MicroMODEL. For further explanation on ROW and COLUMN CLIPPING, see Chapter 11, Plotting.

The user has a choice of how often he would like to have contours labeled. The options appear as:

    Label The contours:
  1. Every contour
  2. Every second contour
  3. Every third contour
  4. Every fourth contour
  5. Every fifth contour

The user also chooses the coloring of the contours. The color coding options appear as:

    Select Contour Coloring Option:
  1. All contours the same color
  2. Labeled contour one color, all remaining contours another color
  3. Cycle through the pen colors

Finally, the user can select the LABELING DENSITY (or how often the contour labels are plotted). Choices range from Low to High.

The CONTOUR CHARACTER SIZE of the elevations is specified as a fraction of the row dimension. A character size of 0.25 results in plotted characters that have a height which occupies one quarter of the row dimension. See Volume I, Section 6.3.8 for more information on selecting character sizes.

Since it is possible to contour on fractions, the user can structure the output format by specifying the NUMBER OF DIGITS AFTER THE DECIMAL when prompted. If the user does not want to have any characters behind the decimal point and also does not wish to display the decimal point, a -1 should be entered.

The Pen Color Selection Screen allows the user to specify PEN COLORS for GLOBAL GRID LINES, LOCAL GRID INTERNAL LINES, LOCAL GRID PERIMETER LINES, LOCAL GRID NUMBERS, and LOCAL GRID TIC MARKS.

If CUSTOM INTERVALS was selected, then the user enters the Number of Contour Values to Enter, and the individual values.

The TITLE BLOCK parameters are set after all program parameters have been set. For a complete discussion of the TITLE BLOCK QUESTIONS, see chapter 11, Plotting.

The Contour Plotting program produces a scaled plot that can be output at any user specified map scale (see Volume I, Section 6.3.7). The SCALE OF THE PLOT determines the plot scale in either feet/inch or meters/meter. For further explanation on SCALE OF PLOTS, see Chapter 11, Plotting.

2.9.6 Perspective View of Grid Values

This program produces a three-dimensional fishnet view of the existing MicroMODEL topography grid. The fishnet plot can be viewed from any point in space that lies above the grid. Several other options are available to produce the desired output.

The plots generated by this program are usually used for verification of modeling, visualization assistance, and report preparation rather than producing actual working maps.

The ANSWER SET NAME simply identifies this set of responses.

Two types of fishnet views can be plotted by the Perspective Viewing program. PERSPECTIVE VIEWING converges some lines at a very distant point to generate an appearance of depth. ISOMETRIC VIEWING plots all grid lines square to the local grid so there is not an appearance of depth due to converging lines.

VERTICAL EXAGGERATION enables the user to enter a factor that scales all values and generates more (factor > 1) or less (factor < 1) relief. The program can also select a vertical exaggeration factor automatically.

The view point is defined by its DISTANCE TO THE EYE. The user can either enter a distance in the project units or elect to have the program select this value automatically.

Depending on the orientation of the viewpoint, the fishnet may contain lines that are "hidden" behind lines closer to the view point. The user can suppress the plotting of hidden lines by responding "Y"es to the HIDDEN LINE REMOVAL question. The hidden line option takes slightly longer to execute but usually produces clearer results.

Row and Column Clipping allows the user to plot a partial section (window) of the model area in perspective. The user defines this window with STARTING and STOPPING COLUMNS and ROWS as prompted by MicroMODEL. For further explanation on ROW and COLUMN CLIPPING, see Chapter 11, Plotting.

Next, a point in space from which the user views the grid is defined. This viewing point is specified by the VIEW DIRECTION ANGLE (an azimuth clockwise from North) from the viewer's eye to the grid. Generally, fishnets have a better appearance if the grid is viewed diagonally. Next, the VIEW DIP DIRECTION is entered (+90 degrees is looking vertically down). Generally, a plunge of 30 to 60 degrees yields the best results.

Ranges of values can be plotted with different pen colors. This produces a useful effect on elevation grids, as each range is plotted at a different color. If this option is desired, the user enters the PEN COLOR INTERVAL or band width. For example if the user wants the fishnet to change color every 50 feet of elevation, he would choose the pen color interval to be 50. To plot the entire fishnet at the same color (pen 1), specify 0.0 (zero) for the pen color interval. Otherwise, the program cycles through pens 1,2,3, and 4.

The TITLE BLOCK parameters are set after all program parameters have been set. For a complete discussion of the TITLE BLOCK QUESTIONS, see chapter 11, Plotting.

The Perspective Plotting program produces a scaled plot (see Volume I, Section 6.3.9). A PLOT SCALE should be specified in either feet/inch or meters/meter. For further explanation on SCALE OF PLOTS, see Chapter 11, Plotting.

2.10 Surface or Thickness File Manipulation

This option allows the user to perform several different types of mathematical and logical operations on up to eight different surface/thickness labels. The results of the operations can be written into any surface/thickness label. This option is especially useful for the creation of synthesized data, such as data that has been limited to a given minimum or maximum value.

This program works exactly the same as 1.14 "Sample Manipulation", and the user should refer to this section for details. If the user writes the results to a surface or thickness model that does not exist, it is suggested that the user change the name of the surface of thickness with either "Change Name of Surface (Cone) Model", or "Change Name of Thickness Model."

2.11 Create Rock Model from Surface Models

This option allows the user to create a 3-D rock model from one or more surface models. Generally, this program is used to create a lithologic model from a set of stratigraphic surfaces. For example, a set of seams may have been modeled which must now be converted into a 3-D rock model. This option can also be used to convert cone surfaces which represent different mining phases or sequences into a 3-D model.

The user must first create all necessary surfaces. Then, the number of surfaces to use is selected, and each surface is chosen in order from top to bottom. For each surface, a rock code is specified which will be used to tag all blocks whose centroids fall above that surface, but are below the prior surface. Note that the original topopgraphy surface, surface model zero, is used as the "prior surface" for the first surface.

The output model can either be the standard rock model (R200), or it can be any 3-D grade model, as specified by label and type.

Blocks that are above the original topopgraphy surface are coded as zero, and blocks that fall below the final surface are coded with the background rock code that is supplied by the user.

The user is responsible for checking consistency between surfaces. For example, if an "upper" surface goes below a "lower" surface, then this program will honor the "upper" surface. Codes for blocks above the "upper" surface, even though they are below the "lower" surface, will receive the code specified for the "upper" surface. It is highly recommended that any rock model that is created be checked by creating a section plot of the surfaces (Pits >Money Matrix> Plot Cone Profiles) and overlaying it onto a plot of the rock model. The figure below is a simplified example of how this program works. Plan View Cell plots of the rock model showing color coded blocks are also helpful for checking this type of model.

                      FIGURE 2.4
                ROCK MODEL FROM SURFACES
                Green Line = Original Topography
                Blue Line  = Surface 1
                Red Line   = Surface 2
                Default Rock Code = 9
                (Blank blocks are air; rock code = 0)

2.12 Change Name of Surface (Cone) Model

The program allows the user to change the name of a surface model (cone) that currently exists in the surface model data base. The user selects the surface to rename and the new name.

2.13 Change Name of Thickness Model

The program allows the user to change the name of a thickness model that currently exists in the thickness model data base. The user selects the thickness model rename and the new name.

2.14 Create Triangulation Model of Surface or Thickness Model

This program creates a Surface or Thickness model using the method of Delaunay Triangles. Data points must alreay have been created using 2.4 Prepare Surface or Thickness Data.

The user can opt to model a subset of the project by choosing starting and ending column and row limits. Then, the surface(s) to be modeled is chosen. Finally, the user may opt to generate a POLY.CNT style output file that contains the triangles that are constructed. The triangles are written to a file whose name must be entered by the user. The triangles may be displayed using choice 2.3.5, "Plot Digitized Data in Plan View."

Once the triangles are constructed, the program loops through the column and row ranges that were specified. For each grid cell that falls inside a triangle, an elevation is calculated based on the elevations of the three corners of the triangle. Since these corner points define an imaginary plane in space, it is a simple matter to calculate the elevation of the imaginary plane at the 2-D grid centroid location.

Note that the program does not reset the value of grid points located outside of any constructed triangles. The user should delete the 2-D surface or thickness data file prior to running this program if the grid points need to be reset.

2.15 Clean-Up Directory

This option allows the user to delete all output files created in the Data Entry Module that are no longer needed in the MicroMODEL system. The files that will be deleted are listed when the program is invoked. The output files that are deleted can always be recreated by MicroMODEL at a later date as needed. Periodically running this program increases usable disk space.