Matthew, I am not aware of a utility that reads ascii point data and directly creates a grid file without any attempt to interpolate. You could take a couple approaches.
One is to write a script in a language like Python that will do the task and write the result out to a GDAL supported grid format. This is not particularly complicated, but it would be hard if you are not a programmer. The other is to restructure the data somewhat into an accepted format, like arc/info ascii grid. This format is fairly simple but it assumes a regular grid of data and you would need to restructure your data appropriately. An example small grid is: ncols 5 nrows 7 xllcorner 440720.000000000000 yllcorner 3751020.000000000000 cellsize 60.000000000000 NODATA_value 132 107 123 132 115 132 115 132 132 123 123 115 132 140 132 123 148 132 123 123 123 156 156 156 140 132 156 100 156 101 102 156 156 156 103 103 Best regards, On Thu, Jan 28, 2010 at 12:57 AM, Matthew Snape <[email protected]> wrote: > Hi, > > I have a set of points in a shapefile that represent gridded height > data. I would like to convert them to a raster without using any > interpolation, merely using each point as the centre of a cell. I have > tried using gdal_grid with the nearest algorithm but this appears very > slow. Is there a better way? > > my current command is: > > gdal_grid -a nearest -txe 420000 640000 -tye 240000 460000 -outsize 4400 > 4400 -of "GTiff" -ot Int16 -co "COMPRESS=LZW" -zfield HEIGHT -l all > all.shp all.tif -- ---------------------------------------+-------------------------------------- I set the clouds in motion - turn up | Frank Warmerdam, [email protected] light and sound - activate the windows | http://pobox.com/~warmerdam and watch the world go round - Rush | Geospatial Programmer for Rent _______________________________________________ gdal-dev mailing list [email protected] http://lists.osgeo.org/mailman/listinfo/gdal-dev
