2008/12/31 吉藤奈津子 <[email protected]>: > Hello. > > I have some trouble in using v.to.rast. > Could anyone help me, please? > > I imported ascii vector data (position data) using v.in.ascii, then > converted it into raster data using v.to.rast as follows; > > v.in.ascii input=test.txt output=test x=2 y=1 z=3 columns='x double > precision, y double precision, z double precision' -z > v.to.rast input=test output=test0 use=z > > I succeeded to import ascii vector data by v.in.ascii. > However, when I comverted vector to raster, the position of raster > data was not in the right place. > A little moved. If I displayed both vector data and comverted raster > data, the vector position data was not shown within the corresponding > pixel of raster. > How can I solve this problem? > > Information about my setting is as follows. > > projection: 3 (Latitude-Longitude) > zone: 0 > datum: wgs84 > ellipsoid: wgs84 > north: 29:00:16.07148N > south: 4:59:43.928556N > west: 91:59:43.92852E > east: 110:00:16.0704E > nsres: 0:00:32.142857 > ewres: 0:00:32.142857 > rows: 2689 > cols: 2017 > cells: 5423713 > > A part of imported ascii vector data: > 19.3|97.83333333|1.1111 > 18.16666667|97.93333333|2.1111 > 19.91666667|99.83333333|3.1111 > 19.13333333|99.9|4.1111 > 18.78333333|98.98333333|5.1111 > (latitude | longitude | data) > > I hope someones's kind help. > I wish you all happy new year!
I think that you need adjust region parameters. Raster maps are created based on the values of region. You can see the active region with: g.region -p If you wish cells aligned with points, you must define a region aligned with your the coordinates of your data point. To see the region covered by the points: v.info map=name_of_point_map You must know or determine separation between points too. Based on the extent of the points map, and the separation between points, you can calculate the parameters for the desired raster map. See parameters res, n, s, e, and w in: http://grass.osgeo.org/grass64/manuals/html64_user/g.region.html Try with the following region to see the effects of region changes: g.region -p res=0:45 vect=name_of_point_map v.to.rast input=test output=test0 use=z Saludos José María
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