NAME¶

r3.stats - Generates volume statistics for 3D raster maps.

KEYWORDS¶

raster3d, voxel, statistics

SYNOPSIS¶

r3.stats r3.stats help r3.stats [-e] input=name [nsteps=integer] [-- verbose] [--quiet]

Flags:¶

-e

 

Calculate statistics based on equal value groups

--verbose

 

Verbose module output

--quiet

 

Quiet module output

Parameters:¶

input=name

 

Name of input raster3d map

nsteps=integer

 

Number of subranges to collect stats from

 

Default: 20

DESCRIPTION¶

r3.stats calculates volume statistics for 3D raster maps. Volumes are created on base of value subranges or groups of equal values. The default number of subranges is 20 and can vary from 1 to infinite. Larger number of subranges will result in larger memory consumption. The volumes are calculated in qubic meters. Null values are marked with "*". If the flag -e is set, the number of subranges will be ignored.

NOTES¶

As with most GRASS 3D raster map modules, r3.stats operates on the cell array defined by the current 3D region settings, not the original extent and resolution of the input map. See g.region. The region setting will not effect the memory consumption of this module. The number of subranges in case of value range calculation or the number of equal value groups effect the memory consumption and the calculation time. The user can expect a huge time consumption to calculate the equal value groups (flag -e) if large region settings occur for maps which have many equal value groups (> 100000).

EXAMPLES¶

Lausanne FOSS4G 2006 3D demo dataset example¶

The 3D raster map geology has three values. Each value represents a specific geological layer, clay = 1, sand = 2 and bedrock = 3. To calculate the volume of each geological layer, we can use the flag -e to group equal values into single volumes. r3.stats geology -e will produce the following output:
num | value | volume | perc | count
1 1.000000 300822000.000 50.13700 50137
2 2.000000 101400000.000 16.90000 16900
3 3.000000 197778000.000 32.96300 32963
4 * 0.000 0.00000 0 Number of groups with equal values: 3 Sum of non Null cells:
Volume = 600000000.000
Percentage = 100.000
Count = 100000 Sum of all cells:
Volume = 600000000.000
Percentage = 100.000
Count = 100000

Generic example¶

#create a small 3D region g.region n=1000 s=0 e=2000 w=0 t=300 b=0 res3=100 #create a raster3D map with row() and null values r3.mapcalc "volmap = if(row() == 5, null(), row())" #run r3.stats with a subrange of 10 r3.stats input=volmap nsteps=10 #the result should look like this
num | minimum <= value | value < maximum | volume | perc | cell count
1 1.000000000 1.900000000 60000000.000 10.00000 60
2 1.900000000 2.800000000 60000000.000 10.00000 60
3 2.800000000 3.700000000 60000000.000 10.00000 60
4 3.700000000 4.600000000 60000000.000 10.00000 60
5 4.600000000 5.500000000 0.000 0.00000 0
6 5.500000000 6.400000000 60000000.000 10.00000 60
7 6.400000000 7.300000000 60000000.000 10.00000 60
8 7.300000000 8.200000000 60000000.000 10.00000 60
9 8.200000000 9.100000000 60000000.000 10.00000 60
10 9.100000000 10.000000001 60000000.000 10.00000 60
11 * * 60000000.000 10.00000 60 Sum of non Null cells:
Volume = 540000000.000
Percentage = 90.000
Cell count = 540 Sum of all cells:
Volume = 600000000.000
Percentage = 100.000
Cell count = 600

SEE ALSO¶

g.region, r3.univar, r.stats, r.statistics, v.univar

AUTHOR¶

S&ouml;ren Gebbert Last changed: $Date: 2011-09-13 22:13:36 +0200 (Tue, 13 Sep 2011) $ Full index © 2003-2014 GRASS Development Team