In the other post about LiDAR data processing in QGIS, I discussed how to make Digital Elevation Map (DEM) from LiDAR data and visualized it in Hillshade. Instead of using usual gray hillshading color scale, I made a little figure for the post which showed a colorful hillshading map like figure 1 below. There was a question, how to make such a beautiful colorful hillshading map? In this tutorial I will answer the question and showing how to create it in QGIS.
|Figure 1. Colorful Hillshading Map|
Let's start this tutorial by adding a DEM data, if you don't have it. You can download it directly from QGIS using SRTM downloader Plugin. For this tutorial I used the DEM data from LiDAR output as in figure 2. It doesn't matter if we use SRTM or other DEM data source, cause it will not change the step by step approach in this tutorial.
|Figure 2 DEM Data|
After adding a DEM data, now let's make hillshading map by right click the DEM layer and choose Properties. The layer properties window will appear as in figure 3. Select Symbology, then for Render type parameter select Hillshade.
|Figure 3. Layer Properties Window|
There are some parameters that can be changed for hillshading visualization as seen in figure 4. The Altitude parameter defines the angle of light source (the sun), where 90 degree is the maximum altitude when the sun's position is perpendicular with the surface, and 0 degree is the minimum angle where the position of the sun is equal with the surface. The Azimuth parameter defines the angle of light direction from the north. Lastly the Z Factor parameter is used to scale the height of a surface in Z axis . Changing those parameters will alter the shadow of the terrain surface, therefore you can use those parameters to tweak the output of a hillshading in order to get a better hillshading visualization. In figure 5 can be seen two hillshadings with different altitude, azimuth and Z Factor.
|Figure 4. Hillshading Parameters|
|Figure 5. Hillshading with different parameters. (a) Altitude 30 degree, Azimuth 45 degree, Z Factor 2. (b) Altitude 45 degree, Azimuth 315 degree, Z Factor1|
Now let's make it more colorful. For that, we need to add the same DEM data, so we have two layers of DEM, one with hillshading and the other one is not. Make sure the recent added DEM data is on the top, then open the properties. Next in the Render type select Singleband pseudocolor. Choose a color ramp for example Spectral, define the color number class and change the Mode parameter to Quantile as in figure 6. Click Apply or OK button to see the result. Figure 7 shows the DEM in the selected color ramp and 5 number of color classes as defined previously in figure 6.
|Figure 6. DEM property layer|
|Figure 7. DEM in pseudo color rendering|
|Figure 8. Color Rendering Option|
|Figure 9. Colorful hillshading|
|Figure 10. Invert Color Ramp|
See the tutorial in the video below