Virtual Rasters and Raster Calculations - Open Source Geospatial Tools: Applications in Earth Observation - page 163

to change the SimpleSource tags to KernelFilteredSource and add the Kernel. To
implement a simple 3

×

3 average (smoothing) filter, just replace all kernel coefficients

to 0 111. Some image viewers such as openev and Quantum GIS can open the VRT

file to view the results directly. To convert the filtered virtual raster to a real raster,
you can use the gdal_translate utility.

.

11.4 gdal_calc.py

The Python script gdal_calc.py allows you to perform raster calculations from
the command line. The raster arguments must have the same spatial dimension in
order to perform the pixel by pixel operations. Both arithmetic ( + , − , ∗ ,/ ) and log-

ical operations ( ) are supported. Logical operations can be combined using

logical_or and logical_and statements. You should take care of selecting
the appropriate output data type to hold the result using the option --type . Existing
output files can only be overwritten if the option --overwrite is set.

<, = ,>

Usage: gdal_calc.py [-A <filename>] [--A_band] [-B...-Z
ₒ

filename] [other_options] --calc

-h|--help
Show this help message and exit.
--calc=CALC
Calculation in gdalnumeric syntax using +− /* or any numpy array functions

(i.e. logical_and()).
-A A
Input gdal raster file, note you can use any letter A-Z.
--A_band=A_BAND
Number of raster band for file A.
--outfile=OUTF
Output file to generate or fill.
--NoDataValue=NODATAVALUE
Set output nodatavalue (Defaults to datatype specific values).
--type=TYPE
Set datatype must be one of ['Int32', 'Int16', 'Float64', 'UInt16', 'Byte',
'UInt32', 'Float32'].
--format=FORMAT
GDAL format for output file (default 'GTiff').
--creation-option=CREATION_OPTIONS|--co=CREATION_OPTIONS
Passes a creation option to the output format driver. Multipleoptions may be listed.
See format specific documentation for legalcreation options for each format.
--overwrite
Overwrite output file if it already exists.