Slope

The slope is the terrain surface inclination in relation to the horizontal plane. Considering a digital terrain model (DTM) of height data fetched from a topographic chart and plotting a tangent plane to this surface in a determined point (P), the slope in P will correspond to the inclination of this plan in relation to the horizontal plan.

In some geological, geomorphic applications it is necessary to find regions with few obstacles or regions exposed to the sun during certain day periods. To answer those questions slope counts with two components: gradient and exposition .

Gradient or Slope is the maximum variation rate in elevation value, it can be measured in degrees (0 to 90º) or in percentage (%); and exposition or aspect is the direction of this measure variation in degrees (0 to 360º).

It is accessible through:

PROCESSING → DTM PROCESSING → SLOPE... 

1. Select Input Layer

2.  Compute: choose the method
            2.1 Slope Unit: choose between degrees or percent (only for slope option).
3. Inform Output Raster Parameters
Resolution X / Y : grid space.
Dimension C / L : number of lines and columns.
Note that these values ​​are calculated as they are edited, when entering resolution the size of the grid is calculated and vice versa.

4. Set Output SRS
  to select output layer SRS.

5. Inform the Output Repository by clicking on:
5.1. (...) to select the output directory and also inform the new layer name to store the result, or
5.2. database icon to select the Data Source and Inform the new Layer Name to store the aggregation result.

6. Click OK to perform the operation or Cancel to close the interface.