[GRASS5] Grass 6 capabilities

roger at spinn.net roger at spinn.net
Wed Nov 2 13:12:14 EST 2005 

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




-------------- next part --------------
ORGANIZATION: 
DIGIT DATE:   Fri Oct 21 13:48:23
DIGIT NAME:   
MAP NAME:     Signed_10.20
MAP DATE:     
MAP SCALE:    24000
OTHER INFO:   
ZONE:         0
WEST EDGE:    326100.24378887
EAST EDGE:    367059.86950018
SOUTH EDGE:   3933110.68061244
NORTH EDGE:   3980179.72918136
MAP THRESH:   0
VERTI:
A  11
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A  5
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A  5
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A  22
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-----------------------------------
A 353881.6011010 3955943.751468          1       
A 353878.6065340 3955535.314833          2       
A 353620.5658150 3956700.705136          3       
A 359404.7854410 3957344.304438          4       
-----------------------------------
# 4 categories
Vector map: Signed_10.20

0.00 0.00 0.00 0.00
1:Owner 1
2:Owner 2
3:Owner 3
4:Owner 4
-------------- next part --------------
ORGANIZATION: 
DIGIT DATE:   Fri Oct 21 13:48:23
DIGIT NAME:   
MAP NAME:     Example 2
MAP DATE:     
MAP SCALE:    24000
OTHER INFO:   
ZONE:         0
WEST EDGE:    326100.24378887
EAST EDGE:    367059.86950018
SOUTH EDGE:   3933110.68061244
NORTH EDGE:   3980179.72918136
MAP THRESH:   0
VERTI:
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A  3
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A  25
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