r.volume generates a table containing the sum of all cells from a input raster map sorted by category on a clump raster map, and optionally generates a vector points map of the centroids for each clump. If a clump map is not specified, the current MASK is used. The MASK can be defined by r.mask. The sum is multiplied by the area of a cell to give the volume occupied by that cell. See below for an example of the output table.
If a clump map is not given and a MASK not set, the program exits with an error message.
r.volume works in the current region and respects the current MASK.
Attribute table linked to the vector map with centroids contains several columns:
Vector points can be converted directly to a raster map with each point a separate category using v.to.rast.
# set computational region
g.region raster=elevation
# compute volume
r.volume input=elevation clump=geology_30m
Volume report on data from <elevation> using clumps on <geology_30m> raster map
Category   Average   Data   # Cells        Centroid             Total
Number     in clump  Total  in clump   Easting     Northing     Volume
-----------------------------------------------------------------------------
     217    118.93  86288828  725562   635325.00   221535.00    8628882798.63
     262    108.97  21650560  198684   638935.00   222495.00    2165056037.02
     270     92.23  63578874  689373   642405.00   221485.00    6357887443.53
     405    132.96  33732662  253710   631835.00   224095.00    3373266208.59
     583    139.35   3011288   21609   630205.00   224665.00     301128821.55
     720    124.30    599618    4824   634075.00   227995.00      59961816.06
     766    132.43    936791    7074   631425.00   227845.00      93679120.08
     862    118.31   7302317   61722   630505.00   218885.00     730231746.74
     910     94.20   4235816   44964   639215.00   216365.00     423581613.11
     921    135.22   1693985   12528   630755.00   215445.00     169398523.05
     945    127.24      1145       9   630015.00   215015.00        114512.03
     946     89.91    365748    4068   639085.00   215255.00      36574833.85
     948    129.02    112632     873   630185.00   215115.00      11263181.57
-----------------------------------------------------------------------------
                                                Total Volume = 22351026655.81
Last changed: $Date: 2014-12-19 22:55:37 +0100 (Fri, 19 Dec 2014) $