2.0 PolyMap MAP EDITING AND DIGITIZING

This module enables the user to digitize geologic data, digitize topography and open pits, and manually edit map files. Other programs associated with these main programs, such as filtering, updating, and meshing, are also included in this sub-menu. The System Setup Menu Choices appear below:

  1. Command Shell
  2. Digitize Geologic Data
  3. Filter Maps
  4. Update Digitized Geology
  5. Add Topographic Profiles or Contours
  6. Interactive Pit Design / Digitize Topography
  7. Check Map for Direction and Figure Eights
  8. Mesh Pit Design(s) with Topography
  9. Join Traces with Common Endpoints
  10. Create a Masking Polygon
  11. Keep Contours In/Outside Mask Polygon
  12. Manually Edit a Map

2.0.1 Introduction to Digitizing

Digitizing, as it applies here, is a method of taking graphical data on a map and entering that data into a computer data file according to its X,Y location. For example, the digitized representation of a line segment would be the X,Y coordinates of the endpoints of that segment. More complicated features, such as topographic contours, are represented as a set of X,Y coordinates that define the endpoints of a string of contiguous segments.

One not-so-obvious, yet crucial, attribute of good digitizing is proper "point density". Too few points produce an inaccurate and jagged-looking trace. Too many points (segments that are too small or short, relative to the complexity of the trace) can waste resources. Ideally, an optimal compromise must be struck to digitize the least necessary number of points that retains the least sufficient degree of accuracy. In general, a wide spacing between points along fairly straight portions of a line, and closer spacing along curved portions should be used. When in doubt, use more points.

PolyMap has a filtering option that will remove unnecessary points from digitized contours, based on a parallel hull filtering algorithm. This filter should be applied to all maps after they are digitized, in order to remove these unnecessary points. Refer to section 2.5 for details.

2.1 Command Shell

This menu choice enables the user to invoke system commands and run external programs without exiting PolyMap. Refer to Section 1.1 for details.

2.2 Digitize Geologic Data

This program uses interactive graphics for entering or editing digitized trace data and area location labels from the digitizing table and/or from the mouse. Commands to the program can be entered through standard windows pulldown menus, via paper menus on the digitizing tablet, or through commands linked to individual digitizing tablet buttons.

Digitized X-Y points can be entered either from the mouse, or from the tablet. When the tablet is used, certain rubberbanding features are temporarily disabled. To re-enable the rubberbanding, FINISH the current command, and then resume digitizing using the mouse.

Prompts appear in a lower-left hand status window on the graphics screen.

To run this program, the user selects "Digitize Geologic Data" from the Map Data Entry Menu. The answerset is selected, and then the map, layer limit, and digitizing table choices are selected. A check box is shown that allows the user to reuse the last locations for paper menus.

If a digitizing tablet will be used, then check the appropriate box. If the digitizer was enabled, then the user must run through the digitizer setup procedure. Use the program help screens for more information on digitizer setup.

Setup points are used as references to convert from table X-Y coordinates to actual map coordinates. A least square fit algorithm is used to minimize the conversion error for each pair of setup coordinates. A minimum of three setup points is required, but as many as 20 setup points may be used in situations where paper stretch is a problem. For three setup points, it is suggested that the user enter the lower left, upper left, and upper right map corner coordinates.

Digitizing input for plan maps is in the same eastings and northings as the map itself. The "X" direction is positive east, and the "Y" direction is positive north.

Digitizing input for North-South sections looking East is in the same northings and elevations as the map itself. The "X" direction is negative north, since higher northing values are to the left. The "Y" direction is positive elevation. Digitizing input for North-South sections looking West is in the same northings and elevations as the map itself. The "X" direction is the positive north. The "Y" direction is positive elevation.

Digitizing input for East-West sections looking North is in the same northings and elevations as the map itself. The "X" direction is the positive east. The "Y" direction is positive elevation. Digitizing input for East-West sections looking South is in the same northings and elevations as the map itself. The "X" direction is the negative east. The "Y" direction is positive elevation.

Digitizing input for Angled sections is in the same elevations as the map itself, however, the horizontal coordinates are in units of length from the lefthand edge of the section. The "Y" direction is positive elevation.

It is suggested that the user mark and number the setup points on the map, in the order that the points were entered on the second input screen. This will help to minimize mistakes during the setup process.

2.2.1 Startup of the Digitizing Program

Once the digitizer setup is complete (if required), the interactive digitizing program starts. If this is the first time that the map has been accessed, then the user is prompted with an additional input dialog. This screen contains two input fields into which the name for the "BORDER" trace, and name for the "TOPOLINE" trace are entered. Refer to the program help for more information.

If any paper menus are to be activated, then the user should choose Settings Menu - "Change Digitizer Menu Settings." Menus should not be placed over a portion of the map that needs to be digitized, since no points can be digitized that are inside the menu border. Digitized coordinates that fall within the menu boundaries are interpreted as commands.

2.2.2 Menu Commands

To enable or disable paper menus on the digitizing tablet, select (Settings - Change Digizer Menu Settings). Follow the instructions provided. Each of the three possible menus can be enabled or disable with a check box. A command button for each menu allows for redefining the menu location.

2.2.3 Data Entry Commands

The DIGITIZE GEOLOGY program accommodates two kinds of data input: Polyline (Trace), and Location.

2.2.3.1Trace Data

Traces are entered with the Polyline command. A trace consists of a string of digitized points which may, or may not, be closed. Each trace is given a label consisting of as many as 16 characters. Refer to the Program Help for more information.

2.2.3.2 Locations

Locations are entered using the Location command. A location consists of a centered symbol "X", which represents an X,Y coordinate location and an associated alphanumeric label. Refer to the Program Help for more information.

2.2.3.3 Using the POLYMENU or LOCMENU Menus

Trace names and area labels can be input from the POLYMENU and LOCMENU menus. These menus can only be used when digitizing (editing) a single layer. Do not attempt to use the POLYMENU or LOCMENU menus when working on more than one layer at a time.

To plot a set of POLYMENU or LOCMANU menus, refer to Section 1.11.

2.2.4 Editing Commands

Several editing commands are available in the digitizing program. These commands allow the user to alter portions of a trace, rename a trace, delete a trace and more. Refer to the Program Help for Details.

2.2.4.1 CLOSEMOVE

This command moves the clo1sure point for closed Polylines.

2.2.4.2 DELETE

This command will remove a trace or location.

2.2.4.3 SPLIT

The SPLIT command is used to split a single trace into separate pieces that have the same name as the original trace.

2.2.4.4 EXTEND

The EXTEND command is used to extend either end of a trace.

2.2.4.5 FLIP

The FLIP command is used to change the direction of a digitized trace. The FLIP command is normally used to correct the direction of digitized topography or pit contours so that their direction meets the criteria of "downhill to the right" necessary for the MESH program to work. Note that a separate program exists in PolyMap that will automatically switch trace directions to meet this criteria (see Section 2.7).

2.2.4.6 IDENT (Query Item)

The Query Item (IDENT) command can identify polylines.

2.2.4.7 RENAMEPOLY

Use the RENAME POLYcommand to change the name of a trace.

2.2.4.8 RENAMELOC

Use the RENAME LOC command to change the name of a location (area identifier).

2.2.4.9 REPLACE

The REPLACE command is used to replace an internal segment of a trace. REPLAC cannot be used to replace a part of a trace that spans the closure point (see CLOSEMOVE).

2.2.4.10 UNDO

The UNDO command will "undo" prior deletes or changes to traces. The UNDO command will only work on traces that were altered or deleted during the current digitizing session.

2.2.5 Display Commands

Several commands are available in the digitizing program to control the current display area. These commands are ZOOM, REDRAW, and LEVELTRC. Refer to the Program help "Display Commands" for details.

In addition, there are many keystroke shortcuts available for panning, zooming, and recalling prior views. Refer to the Program help "Display Commands" for details.

2.2.5.1 BACKGROUND DISPLAY

Any MicroMODEL or PolyMap plot file can be displayed as a background map as a guide for digitizing. Refer to "Display Commands", "Background Display" for details.

2.2.6 Ending a Digitizing Session

When finished with a digitizing session, select "Exit and Save" from the File Menu to Exit and Save your work. Select Exit, Do Not Save to Exit without saving.

At any time, an ASCII (text) backup of the trace data (Polylines) can be made by selecting "Save Current Polylines to ASCII" from the File Menu. Only Polylines that are part of the current layer limits will be saved.

2.3 Filter Redundant Points

This choice allows the user to apply a filter to one or more maps, to eliminate redundant points from digitized traces. The method that the filter uses for eliminating these points is based on a parallel hull filtering algorithm. PolyMap has built-in safeguards that prevent traces from being filtered more than once, since repeated use of the filter on the same trace can cause a more-than-desirable amount of points to be eliminated.

Note: Before any maps are filtered, it is strongly suggested that the user make a backup of the entire PolyMap project folder!

After this choice is selected, the user is presented with a single input screen containing a listing of maps, several choice buttons, and a scale input field.

The choice buttons allow the user to either filter the single map selected with the command button, or filter every map in the PolyMap project.

The input field contains the filter tolerance in user units (feet or meters). The normal filtering tolerance is on the order of 1 unit, which is normally a good choice for typical maps digitized in PolyMap. Use a smaller tolerance to cut down on the number of points that are removed and maintain a "smoother" trace. Use a larger tolerance to increase the number of points that are removed, and create a "coarser" trace.

At the end of filtering the map or maps, the filter program summarizes the total amount of points that were in the map traces before and after filtering. The usual amount of point reduction is in the range of 10-30 percent.

2.4 Update Digitized Geology and Create Polygons

After digitizing geologic data, the raw data must be transformed into a set of polygons. These polygons can then be used for graphical display, and for coding block models for rock type. This section explains how the actual polygons are generated and defined from the digitized data.

When this command is selected, the user is presented with a single input screen containing a map listing and three choice buttons. The map listing allows the user to select a single map to update. The choice buttons allow the user to update the single map, update all maps that need updating, or force an update of all maps.

Any time a map is changed with a graphical editor, or with the manual editor, the map should be updated.

2.4.1 Polygon Construction Sequence

Raw digitized data (traces and locations) are transformed into polygons using the PolyMap UPDATE sequence. Six steps are involved in creating a polygon:

  1. The geology digitizing program is used to enter boundary traces for each map layer.
  2. Areas within these boundaries are defined with the digitizing program to establish area identifier location points within each polygon.
  3. On a layer by layer basis, the boundary traces are broken up into segments and intersection (node) points, which are stored in a node/segment file.
  4. Coordinates of the node/segment file are translated into a standard coordinate system that defines the lower left corner of each map at 0,0. This coordinate translation simplifies certain internal functions within the system. The translation is transparent to the user.
  5. The node/segment file is used to construct polygons for each layer.
  6. Each polygon is defined by using the original locations provided in step (2). If a given polygon is not defined, then the system assigns the name "UNASSGND" to that polygon.

2.4.2 Digitizing Rules for Correct Polygons

So that polygons are correctly constructed, a few simple rules should be followed when traces are digitized for polygon boundaries. Certain situations should be avoided when data are entered for polygon generation. Rules to follow:

  1. Digitizing should always be done from a map that is at the scale specified in the names file. Certain tolerance factors used when generating the node/segment file are calculated from the map scale.
  2. An individual trace can be as long as necessary, but cannot consist of more than 20,000 points. A trace may cross itself as many times as desired, although the user is advised to avoid this wherever possible. It is better to use several individual lines than one, long and complicated line.
  3. If the end of a line is supposed to intersect with another, the shortest distance from the end of the line to the other line cannot be more than 0.1 inch. Preferably, the end of the line should actually cross the other line.

Situations to avoid:

  1. If possible, avoid digitizing boundaries that create a node (common intersection point) with more than four segments coming from that node.
  2. If possible, avoid having a single trace end extend more than 0.3 inches from a node (unless the boundary actually exists). Also, when extending across another line, be sure to only digitize one point after crossing the line. This eliminates unnecessary zero-area polygons, or small unassigned polygons, from being formed.

2.4.3 Node-Segment Side Labeling

After every polygon has been defined, their identifications are used to label the left and right side of each segment in the node-segment file. Left and right refer to the sides of the segment looking in the direction that the segment was originally digitized.

2.4.4 Checking Polygons

After a map has been updated, the map should be checked to insure that every polygon boundary was entered, and that all polygons were assigned an area name. This is most easily accomplished by using the program to display filled polygons to screen. Refer to section 3.9 for details.

The filled polygon plot can be brought up as a background plot file with the DIGITIZE GEOLOGY program. The user can then view the updated (filled) polygons with the actual digitized polygons plotting directly over the filled polygons. The background can be toggled off and on, and the user can zoom in and pan over the entire extent of the map to check for any errors. Each error can be easily and immediately corrected.

2.5 Add Topographic Profiles or Contours

This command allows the user to add topographic profiles to section maps, or to add topographic contours to plan maps. This option gives the user more flexibility than is offered with the automatic process of topography addition that is part of the geologic digitizing program.

The user may add up to five contour types to each map. For sections, only one offset pair is entered, and only the label name is used (the offset is ignored). If a check box is selected, then any old traces that are in the map which map the name(s) of traces being added will be deleted from the map. The user should refer to the program help for details on how to use this feature.

The pairs of offsets and names, when adding topographic contours to plan maps, allow the user to specify the offset distance from the map elevation and label name to use for the contour. The most common usage of this feature is to add TOE, MIDBENCH, and CREST contour lines to a given bench map.

2.6 Interactive Pit Design / Digitize Topography

This program uses interactive graphics for entering or editing digitized trace data (topography or pit contours) from a digitizing table and/or mouse. Commands to the program are entered through standard menus, or via paper menus on the digitizing tablet. Commands can also be associated with the digitizer buttons.

Prompts appear in a lower-left hand status window on the graphics screen.

To run this program, the user selects "Digitize Topography or Open Pits" from the Map Data Entry Menu. The answerset is selected, and then the map, display bench, and digitizing table choices are selected.

If the digitizer was enabled, then the user must run through the digitizer setup procedure. Use the program help screens for more information on digitizer setup.

2.6.1 Startup of the Digitizing Program

Once the digitizer setup is complete (if required), the interactive digitizing program starts.

If the menu(s) must be activated, then the user should choose Settings Menu - "Change Digitizer Menu Settings." Menus should not be placed over a portion of the map that needs to be digitized, since no points can be digitized that are inside the menu border. Digitized coordinates that fall within the menu boundaries are interpreted as commands.

2.6.2 Menu Commands

Refer to section 2.2.2

2.6.3 Data Entry Commands

The only data entry command is Polyline, since this program works strictly with trace data.

2.6.3.1Trace Data

Traces are entered with the Polyline command. A trace consists of a string of digitized points which may, or may not, be closed. Each trace is given a label consisting of as many as 16 characters. Refer to the Program Help for more information.

2.6.4 Editing Commands

Several editing commands are available in the digitizing program. These commands allow the user to alter portions of a trace, rename a trace, delete a trace and more. Refer to section 2.2.4 for a summary of these commands, or the Program Help for Details.

2.6.5 Display Commands

Refer to section 2.2.5

2.6.6 Ending a Digitizing Session

Refer to section 2.2.6

2.6.7 Pit Design Commands

2.6.7.1 EXPANDUP, EXPANDDOWN

The EXPANDUP and EXPANDDOWN commands allow the user to take a pit contour that is either closed or not closed, and expand the contour upwards or downwards according to a given set of slope and road parameters.

This is an extremely powerful feature which can save a mine planning engineer many hours of time in laying out an open pit mine design.

There are several expansion parameters that the user can control. These are:

The default expansion parameters are fixed slope of 45 degrees, expand up one bench, with no road, densify function disabled. The user may change any of these parameters with Expand Menu, "Set Expansion Parameters" selection.

The direction in which the contour that is being expanded was digitized is significant. The user should be sure that the contour is digitized from start to finish with downhill to the right. If the trace was digitized in the reverse direction, the FLIP command can be used to change the direction so that it adheres to this convention.

Normally, the Densify Function is disabled. By enabling the Densify Function, and by setting the Densifying Interval (this is the maximum gap between two points in the original polyline), the user may be able to get more accurate results when expanding with a slope template, or when expanding downwards with a road in a tight pit bottom. It is suggested that the Densifying Interval be on the order of 1/2 to 1/3 of the row dimension for the project. The Densifying Interval cannot be set to less than 1.0 units.

When the Densify Function is enabled, gaps wider than the minimum allowed distance are filled in with intermediate points that are spaced such that the gap between any of the intermediate points is less than the Densifying Interval that is specified.

The user should note that, when displayed on the graphics screen, contours are labelled on the uphill side of the contour line.

When the EXPANDUP or EXPANDDOWN command is selected, the user is shown the current slope selection in the prompt window. The slope parameters can be changed at any time up until the FINISH command is selected.

The way the slope template is applied is as follows. A separate program is run prior to using the template feature which assigns a per-unit horizontal projection for each vertical unit of change to every block in the 3-D model. This value is based on the rock code for that 3-D model location, and the slope for that rock type. Optionally, the user can also add on a fixed distance to allow for safety benches.

For each digitized point of the contour, the program calculates the 3-D block model block (row, column, level) that the point is within. The horizontal projection factor for that block is used to calculate the horizontal expansion distance to use for that particular apex point.

In order to avoid sharp discontinuities in slope, the program calculates a weighted average expansion distance based on the 3-D block that the point is within, along with the eight surrounding blocks on that level.

For more information on creating the slope template file, refer to MicroMODEL documentation, Volume VI.

The Expansion interval controls the vertical distance up or down to move for each expansion. Normally, this value is one bench height An expansion interval of zero is not allowed.

By setting the number of expansions, the user can control how many expansions are performed with each EXPANDUP or EXPANDDOWN command.

The advantage of doing multiple expansions is that the user does not have to repeatedly cycle through the EXPAND-(pick)-FINISH sequence to expand through a large number of levels. However, there is a disadvantage to doing multiple expansions.

Although the expansion algorithm is fairly stable, there are certain instances that cause the expansion to degenerate and begin forming spirograph-like features as part of the expanded contour. When degeneration occurs, the only solution is to delete the trace(s) that have the spirograph-like parts. In addition, the user must also edit the trace that, when expanded, caused the spirograph-like features to occur.

The cause of the degeneration is usually obvious if the user zooms in on the area in question. Normally, the degeneration is caused by either a very acute convex angle, or by a figure-8 in the original trace. The solution is to replace that portion of the contour using the REPLAC command.

The user can change the number of expansions with a single key press if the number of expansions desired is between one and nine. While in the expand command mode, simply press one of the numeric keypads 1-9.

2.6.7.2 Expansion Sequence Without Road

To perform an expansion without road, use the following sequence of steps:

  1. Be sure that the "Enable Road Expansion" check box is Unchecked. Choose the EXPANDUP or EXPANDDOWN command.
  2. Digitize a point anywhere on the contour to expand. It will be highlighted in color ColorHilite. Use the NEWPICK command to select a different contour, if the one desired was not selected.
  3. Optionally change any or all expansion parameters.
  4. Select the FINISH command.

2.6.7.3 Expansion Sequence With Road(s)

To perform an expansion with one or more roads, use the following sequence of steps:

  1. Be sure that the "Enable Road Expansion" check box is Checked. Choose the EXPANDUP or EXPANDDOWN command.
  2. Digitize a point on the first road segment to expand. This segment will be expanded at the road percent entered in the "Road Pick 1" Road Grade Entry Field. The contour will be highlighted in ColorHilite, and the road segment will be highlighted in ColorHiliteRoad. If the wrong contour or segment is selected, use the NEWPICK command, or CANCEL and reselect. Note that the road segment width is displayed in the prompt area. This width should match the desired design width for the road.
  3. Repeat step 2, if desired, for up to three separate roads. Each road can be expanded clockwise, counter-clockwise, or as a slot.
  4. Optionally change any or all expansion parameters.
  5. Digitize the FINISH command.

2.6.7.4 SWBACK

A simple switchback can be implemented using the SWBACK command. This command changes an already existing sidehill road segment into a switchback. To generate a switchback:

  1. From the Edit Menu, select "Construct a Road Switchback."
  2. Digitize a point on the road segment to switchback. This segment will highlight in ColorHiliteRoad, and the contour will highlight in ColorHilite. If the wrong segment is selected, use the NEWPICK or CANCEL commands to choose a new segment.
  3. Digitize the tangent point on the original contour where the switchback will tie back in.
  4. A construction line is displayed showing the proposed switchback configuration. If it is acceptable, enter the FINISH command. If it is not acceptable, cancel the switchback with the CANCEL command.

2.6.7.5 ARC180

The ARC180 command can be used to draw a semi-circle (180 degree arc) of a given radius, starting from the last line segment digitized in the POLYLINE command, the EXTEND command, or the REPLACE command.

This command is useful in constructing switchback designs where the standard SWBACK command will not produce the desired result.

The command is used as follows. While digitizing an original trace with the TRACE command, or extending or replacing part of a trace with the EXTEND and REPLACE commands, enter this sequence of commands:

  1. Select the ARC180 command (Polyline Menu, "Insert 180 Degree Arc").
  2. In the dialog box, enter the desired arc radius. Select the arc direction using the radio buttons.
  3. After the arc has been drawn, continue on as though the arc was input manually.

2.6.8 Volume and Grade Calculations

The pit design program contains two commands that allow the user to calculate tons and volume. The VOLUME command allows the user to calculate the volume of a waste dump, as defined by one or more levels of closed polygons. The RESRV command allows the user to report tons and grade of ore and waste for one or more levels of closed polygons.

2.6.8.1 RESERVES

The RESERVES command allows the user to calculate tons and grade for a set of closed polygons. These polygons should represent one or more levels of an open pit design.

Prior to using this function, the user must create a reserve reporting control file using MicroMODEL.

  1. Prior to selecting the RESERVES command, be sure to choose the reserve file set (Reserve Menu, "Set Reserve Parameters").
  2. Select the RESERVES command (Reserve Menu, "Calculate Reserves").
  3. Pick one or more polylines, or use the right-click feature to select several polylines at once.
  4. Enter FINISH, or a main command to complete the command. The reserves for the selected contour(s) will be shown in a separate file display dialog.

2.6.8.2 VOLUME

The VOLUME command allows the user to calculate a waste dump volume as defined by a set of closed polygons. These polygons should represent one or more levels of a proposed waste dump design.

Prior to using this function, the user must create a set of appropriate work files for calculating waste dump volumes. The user should refer to MicroMODEL Volume II, Section 10.6 for details.

This command will report the total volume defined by one or more closed polylines. Use the VOLUME command as follows:

  1. Prior to selecting the VOLUME command, be sure to choose the Waste Dump Design File Pair (Dump Menu, "Set Waste Dump Design File Pair).
  2. Select the VOLUME command (Dumps Menu, "Calculate Waste Dump Volume").
  3. Pick one or more polylines, or use the right-click feature to select several polylines at once.
  4. Enter FINISH, or a main command to complete the command. The summary of reserves will be displayed in a separate file dialog.

2.6.9 Displaying Other Phases (Cones)

Up to three other plan view maps can be displayed in the background while using the Pit Design Program. The color of each phase can be set, and the line style (solid, dots, dashes) can be set for phase contours that are above the current bench, below the current bench, or that match the current bench.

Labeling of the contours can be enabled or disabled. Disabling the labels can help eliminate clutter in the display.

A fixed offset can be added to the phase contours, if desired. This is useful for designing leach pads, where the total change in elevation between lifts cannot exceed a certain number of feet or meters. By displaying the prior lift with an offset equal to the maximum change in height, the user can immediately see where the limits of the current designed lift are.

Phase parameters are set using the (Phases Menu, "Set Background Phase Display Parameters") choice.

The phases can be toggled on and off with the (Phases Menu, "Show Background Phases") choice.

Refer to the program help for more details.

2.7 Check Map for Direction and Figure Eights

This program is used to check traces for figure 8's, and to adjust topography so that all contour lines are written in the direction with downhill to the right. Removal of figure 8's is a must for getting error-free results from the meshing program, as is having topography digitized in the correct direction.

After selecting this program, the user must choose an answer set. Then a single input screen is displayed which contains one input field, one command button, and two choice boxes.

Enter the answer set name in the input field. Select the map to check with the command button. Choose whether or not to adjust traces for correct direction with the first choice box. Choose whether or not to check for figure eights with the second choice box.

Direction checking is not "foolproof" and for certain traces, especially isolated traces along the right- and left- hand edge of the map, the program may not be able to resolve the direction. The user is informed of these traces and should note their location.

If figure 8's are found, the program first tries to fix the figure 8's automatically. If it cannot, the user is informed of the trace name, trace record, and location of the figure 8. The user should note this information and fix the figure 8's with the digitize program.

Figure 8's are locations where a traces crosses over itself. Normally, it is possible to see a figure 8 by zooming in with high magnification on a trace that contains a figure 8. Use the digitizing program X-Y coordinate echo feature to locate the X,Y location of a figure 8, and then zoom in on this location. Use the REPLACE command to eliminate the figure 8.

2.8 Mesh Pit Designs with Topography

This choice allows the user to "mesh" (combine) one or more pit designs with original topography and form a "meshed" topography map. This composite map can then be displayed to create final copies of pit designs for reports, etc. By using the MESH program, the user can check to see that the pit design interfaces correctly with original topography, and that no errors were made in the actual pit design, such as entering the wrong elevations.

2.8.1 Preparing for Meshing

In order to mesh, the user must have a starting topography map that one or more pit designs will be meshed into. This can be an original topography map, or it can be map that was created with mesh to form a previous pit phase.

All input maps should be filtered (section 2.5), joined (section 2.12), and checked for figure 8's and proper direction (section 2.13). Topography contours for bench midpoints or bench toes must exist in the starting topography map, and the pit designs should have been done on either bench toes or midpoints.

In addition, the user must be sure that a map has been pre-defined for storing the results of the meshing.

After selecting this program, the user must choose an answer set. Then, a single input screen is displayed which contains several input fields, command buttons, and check boxes.

The first input field is the answer set name. An input field to the left of the pit names defines the number of different pit maps that will be meshed with the topography map. Up to 8 pit maps can be meshed at once. If a waste dump design is being meshed, only one waste dump can be meshed at a time due to a difference in the way the program handles waste dumps.

Each pit to be meshed is selected from a pulldown menu box. Directly to the left of the box containing the pit names is a check box that is used to signal if a waste dump is being meshed. Leave the check box unselected for pits, and select the check box for waste dumps. For each pit to be meshed, you may enter a minimum and maximum elevation to mesh from that phase. This feature is useful for creating end-of-period maps.

Two other drop down menu boxes appear at the top of this input screen. The first is used to choose the name of the map into which the meshed results will be written. The second is used to choose the name of the map that contains the topography to be meshed.

Two input fields are used to control the minimum and maximum level that will be meshed. Normally, these fields are set at 1 and the number of levels in the project; however, the user may choose to limit the number of levels that are meshed with these values.

Another input field contains the pit contour offset to use. This number should normally be either 0.0 or one-half of a bench height. The value entered in this input field depends on the check box located below the field. The check box determines whether toe elevations or midpoint elevations are pulled from the topography file for meshing. The pit traces must be adjusted to match whichever choice is used for the topography elevations.

If midpoint elevations are pulled from the topography file, then the pit contour values must be adjusted so that they match the midpoint. If toe elevations are pulled from the topography file, then the pit contour values must be adjusted so that they match the toe. For example, if meshing is performed using toe elevation contours from the topography file, and the pit design was made based on toe elevations, then the offset value is 0.0. If meshing is performed using midpoint elevations from the topography file, and the pit design was made based on toe elevations, then the offset value is one-half of the bench height.

2.9 Join Same Name Traces with Common Endpoints

This command is used to join the common endpoints of different traces. The endpoints must be within a specified tolerance distance, and the traces that are joined must have the same label. The join program is normally used in situations where two adjacent maps were digitized separately, but must now be consolidated into a single map. It is also used to consolidate maps that were created with the MESH program (Section 2.14).

The map for which to join endpoints is selected from the list of maps. The tolerance factor for joining endpoints is entered in appropriate input field. The check box is selected if the map was created using the meshing program (see section 2.14).

The tolerance value for joining traces is entered in feet or meters. Endpoints that are within plus-or-minus this tolerance in both the X and Y directions will be joined, provided they have the same name (see next paragraph).

If the map was created with the mesh program, then the check box should be selected, otherwise, leave the check box unselected. If the check box is not selected, then only traces with names that match exactly will be considered for joining. If the check box is selected, then only traces that can be read as having the same elevation value will be considered for joining.

After a map has been run through this joining program, it should be checked for figure 8's before proceeding with any other programs (refer to section 2.13).

2.10 Create a Masking Polygon

This choice allows the user to take a digitized polygon from one of the maps, convert it, and write it to an ASCII file. The masking polygon is used by the program that keeps contours inside or outside a masking polygon (see section 2.16).

After choosing this program, the user must select the appropriate answer set. Following this, the first input screen is displayed which contains two input fields and a map listing. The map from which the masking polygon will be extracted is chosen from the list of maps. The first input field is the answer set name and also the title for the masking polygon. The title is written to the first line of the ASCII output file. The second input field contains the name of the ASCII output file. The Access Directory Button can be used to access the computer directory.

The subsequent input screen will display a list of all the polylines contained in the selected map. Choose one of these polylines that will act as the masking limit.

When the program has finished, a file will have been created that contains the title , followed by the X-Y points of the polygon, followed by a program flag.

2.11 Keep Contours Inside or Outside a Masking Polygon

This choice allows the user to keep the portion of a map that is either inside or outside a masking polygon.

When this program is invoked, the user must select the appropriate answer set. Following this, a single input screen is presented which contains two input fields, a list of maps to choose, and two radio buttons. The first input field is for the answer set name. The second input field contains the name of the polygon masking file. This should be the name of the file that was created previously (see section 2.14). The Access Directory Button can be used to browse the user's computer directories.

The map that will be masked is selected from the list of maps. The radio buttons determine whether items will be kept inside or outside the masking polygon. This program uses the same map for input and output, that is, the original map contents are changed. It is a good idea to copy the contents of the original map into a working map, then apply the masking polygon to the working map. This way, if a mistake is made, such as choosing the wrong area to mesh (inside instead of outside), then the original map is still intact.

2.12 Manually Edit a File

This choice allows the user to interactively edit a map file using keyboard input. It is a simple program that is provided so that single or global changes to trace and/or area names can be made. Single or global deletions can also be made.

When this choice is selected, the user is first presented with a list box of map name choices. A map name should be selected from this list.

Next, the user is presented with one or more similar input screens, one screen for each trace or location entry in the map. At the top of each screen, the user is shown the name of the map being edited and which record number of the total record numbers is currently being edited. The user can move from screen to screen with either the Next Record or Previous Record Buttons.

There is one set of choice buttons, a string input field, a "jump to" input field, and one set of command buttons in each of these input screens. The single input field is for entering the new trace name or area name, when the user is changing this name. The first set of choice buttons allows the user to make single changes; that is, to change or delete the current record. The command buttons allow the user to make global changes to all map records that match the name of this trace (if the current record is a trace), or match the name of this area (if the current record is an area).

After changes are made, the user may unchange them at any time. Deleted entries can be undeleted at any time. When the user is finished, then he may elect to continue, in which case all changes and deletions are made and the map is updated. Otherwise, the user can quit the program, in which all changes and deletions are canceled and the map is kept in its original form.