Processing and analysis

Now we are ready to start processing our dataset and make some scientific analysis.

The most common use cases of raster data are imagery, DEM, and statistical data. Right now, we'll look closer to Digital Elevation Model processing.

We can use the following:

• ST_Slope
• ST_Hillshade
• ST_Aspect
• ST_TPI
• ST_TRI
• ST_Roughness

All these functions are internally realized as MapAlgebra Callback functions. Later we will see how to do it on our way. So, calculate the slope values of our DEM data. The function syntax is like this:

ST_Slope(raster rast, integer nband=1, text pixeltype=32BF, text units=DEGREES, double precision scale=1.0, boolean interpolate_nodata=FALSE); 

We should especially pay attention to scale parameter. In case of geographical coordinate reference systems (such as our imported data), when units of distance are in degrees, and elevation in meters, use scale=111120, or in case of imperial units set it to 370400. Units parameter offers DEGREE, RADIANS, or PERCENT as a result...