====== Geotricks ====== This page is dedicated to sparse and casual tricks with some common GFOSS tools. ===== Merging multiple Geotiff bands ===== This command works with relatively recent [[http://gdal.osgeo.org/|Gdal]] versions: gdal_merge.py -o multiband.tif -separate band1.tif band2.tif band3.tif ===== Changing raster resolution in Grass ===== Just use the builtin computing region facility, it will use a nearest neighbor interpolation for this purpose: g.region rast=original_map -p g.region res= r.mapcalc "new_map=original_map" A similar trick can be used to cut a portion of the original map, apply a mask, etc. A more capable module for those applications is ''r.resamp.interp'' which can be used instead of ''r.mapcalc'' to peform also bilinear and bicubic interpolation for the assigned raster grid. A nearest neighbor interpolation can also be performed by the ''r.resample'' module as well. ===== WMS/WFS at PCN ===== See [[WMS at PCN|here]] for details about using GRASS with national service at PCN. ===== Precision grid ===== [[http://lists.maptools.org/pipermail/proj/2011-April/005628.html|This]] is a very interesting thread about creating proj NTv2 precision grids starting from national precision grids in other formats, up to about 1:2000 scale and more.