For terrain analysis it can be useful to be able to calculate a map of the slope and aspect of a DEM. For example, classifiers may want to exclude data from areas with steep slopes. Slope represents the rate of change or steepness between neighbouring elevations. Aspect identifies the downslope direction of the maximum rate of change in value from each pixel to its neighbors or in other words, the slope direction with respect to North.SNAP actually already calculates the slope of a DEM within the terrain masking operator but does not expose it to the user as an output. We will implement a stand alone operator to add slope and aspect bands to a product containing an elevation band.