I have a data source (a US state) whose GIS data files in .gdb format lack
clean topology. v.in.ogr reports (for one example) that 29671 polygons
overlap and suggests re-importing starting with snap=1e-09. I end up
re-running v.in.ogr through snap=0.1 without completely fixing all overlaps
and other errors. One question is: how many times should I re-run v.in.ogr
with different smap tolerances if the data are not fixed?
Next I run v.clean using snap as the tool and 1 as the threshold. For many
of these files this does not fix all the errors.
While I can use v.build to see the errors I would like to better understand
the work flow for removing all errors that occur when importing with
v.in.ogr. How can I most quickly generate fully topologically clean output?
TIA,
Rich
On Tue, 18 Aug 2020, Rich Shepard wrote:
While I can use v.build to see the errors I would like to better
understand the work flow for removing all errors that occur when importing
with v.in.ogr. How can I most quickly generate fully topologically clean
output?
Update:
I ran v.in.ogr three times, then v.clean with tool=snap and threshold=1. The
results are:
Rebuilding topology for output vector map...
Building topology for vector map <clean_soils@PERMANENT>...
Registering primitives...
Building areas...
100%
Attaching islands...
100%
Attaching centroids...
100%
WARNING: Number of centroids exceeds number of areas: 228861 > 227947
WARNING: Number of incorrect boundaries: 23302
WARNING: Number of centroids outside area: 1146
WARNING: Number of duplicate centroids: 298
Could the original ESRI maps be this poor? What more can I do to eliminate
these warnings?
This is new territory for me and I need to learn how to resolve these
issues.
Regards,
Rich
On Tue, 18 Aug 2020, Rich Shepard wrote:
While I can use v.build to see the errors I would like to better understand
the work flow for removing all errors that occur when importing with
v.in.ogr. How can I most quickly generate fully topologically clean output?
I used the wrong v.clean options. What works for both .shp and .gdb files
that have issues after being imported is:
v.clean input=<mapname> output=<mapname>_clean tool=bpol,rmdupl type=boundary
Rich