convert time series of DEMs into voxel model and visualize using isosurfaces and slices
create voxel models for attributes to be displayed as color on isosurfaces
Space-time cube: GRASS solution
Improved and more detailed steps from the report.
# generate helper map
r.mapcalc "legend_map_1974_2012 = if(col()==1, 1974, if(col()==2, 1995, if(col()==3, 1998, if(col()==4, 1999, if(col()==5, 2001, if(col()==6, 2007, if(col()==7, 2008, if(col()==8, 2009, 2012))))))))"
# set color table for helper map (same as voxel color table)
r.colors map=legend_map_1974_2012 color=bcyr
# use d.mon or g.gui to pop up map display
d.mon wx0
# create legend with use parameter set to all valid years
d.legend map=legend_map_1974_2012 \
use=1974,1995,1998,1999,2001,2007,2008,2009,2012 at=10,50,20,30 -f
# now save the display (in d.mon) or take a screenshot
# (e.g. in Ubuntu using Shutter and Selection option)
Creation of helper map is not still ideal. It would be better if it would go over both rows and columns (so the number of cells in region would have to be only the number of years). Moreover, the script to generate the r.mapcalc command is needed to make it easily usable. Also note, that this is a workaround, better would be d.legend supporting 3D rasters.