Create Plot Overlay

Use the SEM-Plot > Create Plot Overlay option (SEMOVERLAY GX) to create an overlay and overlay map file from a map group.

Create Overlay from Map Group

Overlay name	The name of the overlay, containing the Stage and Oxide selections, and the instructions for drawing the overlay, including a reference to an overlay map file name. Script Parameter: SEMOVERLAY.OVERLAY
Map group name	The map group which is to be saved as an overlay. Map groups which should not be used for creating an overlay map are removed from the drop-down list of available groups. Script Parameter: SEMOVERLAY.GROUP

Application Notes:

Overlays and Template files

To simplify usage, the files used to store plot templates and overlay information have been "hidden" from the user. Instead, lists are created of available templates and overlays from the files stored in the Geosoft\Desktop Applications \etc and %USERPROFILE%\Documents\Geosoft\Desktop Applications \etc directories. Modified or new templates and overlays are stored in the %USERPROFILE%\Documents\Geosoft\Desktop Applications \etc folders to avoid overwriting the original templates and overlays.

There are two types of template files, one for XY plots and one for TRIangular plots. These are created automatically when using the XYplot or TRI plot menu commands. These template files are ASCII files.

There are two valid overlay file types: one for an XYPLOT and one for a TRIPLOT. The following is a typical XYPLOT overlay header:

The following is a standard TRIPLOT overlay header:

The salient differences are the "XYPLOT" or "TRIPLOT" keywords, and the presence of the ZStage: and ZField: fields in the TRIPLOT overlay.

The header is what allows us to restrict the use of particular overlays to particular plots. The following are the possible values for the #Stage: fields:

• Raw Data Stage
• Fe Corrected Stage
• Fe Normalised Stage
• Cation Stage
• Recast Stage
• Ratio Stage

 

Any number of the following commands may following the header:

 

LineType: 1 0  // The first number is the style, the second is the pitch, in the view "X" axis units (usually %).

LineCol: R G B  // R, G, B are the Red, Green and Blue values in the range 0-255. Black is 0 0 0

LineSmooth: # //where # is 0: no smoothing, 1: cubic spline, 2: akima spline

Line: N   // N is the number of points in the line segment that follows. Each point is an X and a Y value for an XYPLOT overlay, and the X and Z (Y-Axis) value for a TRIPLOT overlay. Each point is written on a single line, so if N=10, it would expect 10 lines of X Y pairs.

For example: The following draws a box.

Line: 4

0 8

8 8

8 0

0 8

XYTrans: 1  // This is a special command for the TRIPLOTs. If this value is 0, then the point locations for lines are given in the view coordinates, using the X and Z channel values. The X channel goes from 0 to 100 across the bottom of the triangle, but lines of equal X are not vertical, as in a normal cartesian plot, but are at a 30 degree angle to the left of vertical. The Z values go from 0 at the bottom of the triangle to 100 at the top, but the Z spacing (vertical) is not the same as the X spacing going horizontally across the bottom. It is more convenient to use XYTrans: 0 because you can use the values read right off the plot using the cursor location (which gives X and Z).

Most of the current overlays use cartesian X and Y locations, because the old SEMPLOT "faked" the triplot. The following transform takes you from cartesian (X, Y) to Triplot (Xt, Zt) coordinates:

Zt = Y * sqrt(3)/2

Xt = X - Zt/2

 

The following commands allow labels to be plotted:

Creating a Map-based Overlay (For advanced users only)

Any label or decoration applied to a map using the standard Oasis montaj map editing tools can be stored for use as an overlay. The following procedure is required:

1. Plot the map for which the overlay is required. The map may already have an overlay defined. Be certain that the current map view is set correctly. It should be (for instance) "XYPlot_GarnetSobolev" for the Garnet Sobolev plot.

2. Create a new group to put the annotations into (New Group... from the "Mapping" menu). Suggested group names are "Xyplot_Map_Overlay" or "Triplot_Map_Overlay". This can now be accomplished by selecting the "New Map Overlay Group..." item from the "Semplot_Plot" menu.

3. Edit the map using the standard Oasis montaj map editing tools. (See standard Oasis montaj help for assistance in editing a map).

4. Run the SEMOVERLAY GX. Select a name for the overlay, and the map group to save as an overlay from the list of groups. (The overlay file and map are saved automatically to the %USERPROFILE%\Documents\Geosoft\Desktop Applications \etc folder).

5. The new overlay will become visible and available for use in the relevant plot templates (e.g. those sharing the same "Stage" and "Oxide" values.)

   To use the new overlay with an existing plot template, edit the template and select the overlay from the list of available overlays. Remember, both the stages and oxide values must match in order for the overlay to appear in the list of available overlays.