It appears to me that the difficulties I originally described with importing
shape files to GRASS 5.3 are actually two or more different problems. I
compiled two examples from a single imported shape file.
The first example below contains 4 complete polygons -- none of which share a
common node -- along with the necessary att and cats files. The polygons
should be correctly supported by GRASS 5. If, after the file is set up as a
valid GRASS vector file, you use d.what.vect to query the left-most polygon the
program will highlight all 4 polygons and produce bad information about the
polygon area. Similar problems occur with other modules that need to identify
the polygons.
I don't have a clue what might cause the problem in GRASS 5. My main concern is
whether GRASS 6 suffers the same result.
The second example contains 3 complete polygons composed of 7 lines. The
polygons all share a single node. v.support reports several "Unclosed area..."
errors. In this case, I can resolve most of the errors by patching the lines
together so there is one line and one node for each polygon. If the polygons
still share a node then v.support will still report errors and fail to support
the polygons. If the sequence of points in the lines are rotated so that the
polygons do not share a node then polygons can be supported.
The question with this is whether GRASS 6.X can import and support these
polygons without errors.
Thank you for your attention.
Roger Miller