landam
commented
5 years ago Comment by huhabla on 28 Jan 2015 23:16 UTC I have just committed a new temporal module called t.rast.what in trunk (https://trac.osgeo.org/grass/changeset/64349 - https://trac.osgeo.org/grass/changeset/64351) that utilized r.what to sample space time raster datasets using vector points. It provides three output layouts that transforms the r.what output into row or column layouts. It can run several r.what processes in parallel using a maximum of 400 raster map layer in a single r.what process.
Please have a look at it.
Any feedback about its performance, usefulness and handling is highly welcome.
Improving r.what to allow more than 400 maps is simple, just edit the fixed value in the source. But, editing this value may cause open file handler limit problems with your OS. However, these limits can be adjusted at kernel level configuration for Linux.
Implementing a more intelligent file handling solution requires more effort.
Reported by sbl on 28 Jan 2015 14:27 UTC r.what is currently the most efficient tool for sampling (single) STRDS at point locations. Usage of r.what for space time data sets however is hampered by the current limit of 400 maps. Would be nice if that limit could be overcome. Memory may be an issue in case of thousands of maps?
See discussion on the mailinglist: http://thread.gmane.org/gmane.comp.gis.grass.devel/62452/focus=62472
In that context also an option/flag to choose between vertical and horizontal output would be useful (columns for thousands of maps will probably trouble spread sheet software).
Finally, when using a vector map as input it would be nice if the category (or content from another column) could be written into the "site name" column of the output, so a resulting table can be linked more easily to the original data.
GRASS GIS version and provenance
svn-trunk
Migrated-From: https://trac.osgeo.org/grass/ticket/2564