2008/6/18 Hamish <[EMAIL PROTECTED]>: > Paulo Marcondes wrote: > >> I had issues while triyng to import an ASCII vector file, >> that looks like this: >> >> B 240 1 >> 333967.494 7610503.977 > .... >> 334065.141 7610992.215 >> 334260.436 7610601.634 >> 1 1 >> >> This should be a polygon that limits a very interesting >> feature. > > missing a centroid?
I thought v.build would fix that for me. So I have do add by hand? Also, where does a centroid goes, I mean, any point inside the boundary, or some other specific place? >> Also, I didn't manage to, while exporting to shape, >> have the polygon filled. (the GRASS polygon fills OK) > > see example in v.out.ogr help page for areas -> shapefile. > >> Also, I had issues while trying to import an 815k lines >> ASCII vector file, ... > Not sure, do you need one coordinate per "P"? > if only points, probably better to use "v.in.ascii format=point" > and forget about all the formatting stuff, just give it a flat .csv file. ... > you need to use v.in.ascii's "format=standard" if data is given in that form. > "standard" format is not the default and should be renamed for GRASS 7 as the > name is somewhat misleading. > Did it used to be "format=grass" ? Left it alone. r.in.xyz works great for my needs. You are right with regards to the standard format, the name is a bit misleading. >> When I imported (almost) the same ASCII file with r.in.xyz, >> somewhere in the northern part of the raster I got a blank >> E-W line, that I feel has something to do with that resolution >> difference (99.97 vs 100m) > > probably that is correct, caused by a partial Moiré effect. > > adjust the res to be exactly 100 by expanding the bounds of the region with > "g.region res=100 -a". It works! Raster loaded beautifully. > grass uses the grid as cell bounds, not cell centers. so west= is the coord > of the left of the leftest cell, and east= is the coord of the right of the > rightest cell. > ie 0,0 falls on a grid confluence, not a cell center. Good to know. I thought otherwise. >> So, what I tried to do was import as vector points to >> interpolate and generate a nice raster. > > I've had success with that method + r.in.xyz, see > http://grass.osgeo.org/wiki/Marine_Science#Import_using_GMT > tip: use a "n" map + r.univar to check that your alignment is correct. Cool. Saves a lot of guessing. -- Paulo Marcondes = PU1/PU2PIX -22.915 -42.224 = GG86jc
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