Geology: Difference between revisions

Revision as of 08:49, 18 September 2011

See the IconSymbols wiki page

(two displayed, one of which has been rotated 180 degrees)

ps.map can take rotation angle from an attribute column for each site with the vpoints rotatecolumn instruction; for d.graph you can prepare a command file with a custom rotation for each point using v.out.ascii, v.db.select, or the v.out.ascii.db addon script. Note that GRASS uses the Cartesian convention for rotation angles, i.e. CCW from east. Convert from compass angles (CW from north) with:

    theta = 90 - degrees_true

You could possibly write a small db.execute script to populate a new column with this conversion by way of a SQL query. (and post it here :)

to make open symbols set the fill color to 'none'.
to make a double sided dip symbol draw the same symbol twice with 180 rotation the second time.

AreaFillPatterns: ps.map allows custom fill patterns based on simple PostScript-like rules files. A number of patterns are provided. It is reasonably simple to create new ones- just copy an existing one to a new file and edit the drawing coordinates in a text editor. (new contributions welcome)

In ps.map use the vlines style instruction to set the line style. The linecap instruction can further refine the draw mode.

@@ Line 21: / Line 21: @@
 * <tt>geology/strike_line,box,triangle,circle</tt>:
 : [[Image:Symb-geo.png|350px]]
+* <tt>geology/half_arrow</tt>:
+: [[Image:Half_arrow_x2.png]]
+: (two displayed, one of which has been rotated 180 degrees)
 * {{cmd|ps.map}} can take rotation angle from an attribute column for each site with the '''''vpoints''' rotatecolumn'' instruction; for {{cmd|d.graph}} you can prepare a command file with a custom rotation for each point using {{cmd|v.out.ascii}}, {{cmd|v.db.select}}, or the ''v.out.ascii.db'' addon script. Note that GRASS uses the Cartesian convention for rotation angles, i.e. CCW from east. Convert from compass angles (CW from north) with:
       theta = 90 - degrees_true