[GRASS5] Import problem

[Rich Shepard]

On Sun, 24 Jun 2001, Robert [iso-8859-1] Lagac=E9 wrote:

> We have about 20 map in Mapinfo format (.map) that we would like to impor=
t
> in GRASS.  Since GRASS cannot import (.map) maps, we converted them in
> Arc/info shape files and mapInfo (.mif).

Robert,

  The polygon conversion/topology building sections of v.in.shape and
v.in.mif are still buggy, unfortunately for many of us. But, one problem
that tripped me up may also apply in your case: overlapping areas.

  MapInfo permits a single table to have overlapping regions. Because MI
does not support topology this is not a problem for the program; the lines
are only graphic objects. But, the two modules cannot properly import this
mess because they have no way of identifying a line with a polygon when the
lines cross.

  What I did with a mine claims map was to manually separate the one MapInf=
o
table into five separate tables so each table had regions that did not
overlap any other -- even slightly. I then exported them as shapefiles and
.mif files. In my case, the former worked a bit more cleanly when importing
them into GRASS.

  The other consideration is to ensure that the projections and coordinate
systems are consistent between MapInfo and GRASS.

HTH,

Rich

Dr. Richard B. Shepard, President

                       Applied Ecosystem Services, Inc. (TM)
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