# Oft-filter

### From Open Foris Wiki

**oft-filter - moving window filters**

**Usage:** oft-filter [-ot {Byte/Int16/UInt16/UInt32/Int32/Float32/Float64/CInt16/CInt32
/CFloat32/CFloat64}] [-h] [-x xdim] [-y xdim] [-c const] [-n nodata][-f filter][-v] <-i inputfile> <-o outputfile>

**Options:**

[-h] print this help [-i input] input file name [-o output] output file name [-x #] Window size in x-direction (default=3) [-y #] Window size in y-direction (default=3) [-c #] Constant used to multiply the resulting value [-n #] Input NoData value, ignored in calculation (Def. from infile) [-v] Verbose [-f #] Type of statistics to be computed (default=1): 0: mean 1: standard deviation 2: variance 3: skewness 4: rank 5: coefficient of variation: 100*std/mean

The program computes local statistics on values of a raster within the zones of a moving window.

## Exercise:

- Get Example data set
- For this exercise following tools are used:
**oft-filter**

1. For this exercise we use the Lansat imagery landsat_t1.tif

2. Open your working directory using

cd /home/...1

3. Examples:

- In the first exercise we want to create the
**standard deviation**for the moving window using the default window size and default statistics (without defining -f). The output image is called std.tif:

oft-filter -i landsat_t1.tif -o std.tif

- Now we go through an example calculating the
**coefficient of variation (100*std/mean)**using the option -f 5. Output: coe_var.tif

oft-filter -i landsat_t1.tif -o coe_var.tif-f 5.

- Calculation of the
**mean**using the option**-f 0**. Output: mean.tif

oft-filter -i landsat_t1.tif -o mean.tif -f 0

4. Load your computed rasters in QGIS and verify your output statistics using **Identify Results**.

- Example of the computed mean.tif:

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