Creating Beautiful Hillshades in QGIS

This tutorial will guide you through the process of creating a stunning hillshade using QGIS. Hillshading is a technique used to visualize the terrain of a given area, providing a more appealing understanding of the landscape.

Step 1: Save Your Project and Set Coordinate System

The first thing you need to do is save your project. After saving, set the project coordinate system to WGS 84.

Step 2: Add Your Elevation Raster

Next, go to Layer > Add Layer > Add Raster Layer to add your elevation raster. For this example, we will use an SRTM model sampled at a 30-meter resolution.

Step 3: Access the Hillshade Tool

Open the Processing Toolbox by navigating to Processing > Toolbox. Search for “hillshade” and select the Hillshade option under Raster Analysis.

Step 4: Configure Hillshade Parameters

In the hillshade algorithm, select your elevation layer. Set the Vertical Angle to 45 degrees and adjust the Smooth value as needed. Save your hillshade output as “hillshade something” and run the process.

Step 5: Style Your Hillshade

Once the hillshade is generated, it may not look appealing right away. To improve its appearance, navigate to the properties of your elevation layer. Under Symbology, change the Render Type to Singleband pseudocolor.

Step 6: Select a Color Ramp

Click on the color ramp option and create a new color ramp. Choose a suitable color ramp for topography, such as “sd_a”. Click Apply and then OK.

Step 7: Adjust Hillshade Blending Mode

Turn on your hillshade layer and go to its properties. Under Color Rendering, set the Blending Mode to Multiply and apply the changes.

Step 8: Fine-Tune Transparency

To enhance the visual quality further, adjust the transparency of the hillshade layer. Set it to around 80% and apply the changes.

FAQ

Here are some frequently asked questions (FAQs) about creating hillshades in QGIS:

What is a hillshade in QGIS?

   – A hillshade is a 3D representation of terrain on a 2D map that simulates the effect of light and shadow on the surface. It is created from a Digital Elevation Model (DEM) to enhance the visualization of terrain features such as hills, valleys, and ridges.

What is the difference between a hillshade and a DEM?

   – A DEM represents the elevation of the terrain as a raster grid, while a hillshade is a derived raster that visually represents the DEM by simulating shadows and highlights based on light source angles.

What are the key parameters for generating a hillshade in QGIS?

   – The key parameters include azimuth (the compass direction of the light source), altitude (the angle of the light source above the horizon), and the Z-factor (a scaling factor for vertical exaggeration to enhance terrain features).

How can I customize the appearance of a hillshade in QGIS?

   – You can customize the hillshade’s appearance by adjusting its transparency, changing the color ramp, combining it with other layers (e.g., DEM or contour lines), or overlaying it with different blending modes (e.g., multiply, overlay).

What is the Z-factor in hillshade creation, and why is it important?

   – The Z-factor is used to convert elevation units to match horizontal units or to exaggerate the terrain’s vertical dimension. It is especially important when working with DEMs in different coordinate systems or when you want to emphasize subtle terrain variations.

How do I combine a hillshade with a DEM in QGIS to enhance visualization?

   – You can combine a hillshade with a DEM by setting the DEM layer’s rendering mode to “Multiply” or “Overlay” in the Layer Properties. This approach allows the color information from the DEM to be visible, while the hillshade provides shading.

What is multidirectional hillshading, and how is it different from traditional hillshading?

   – Multidirectional hillshading uses multiple light sources from different directions to reduce the bias of shading from a single direction. It provides a more realistic and less directional appearance of the terrain compared to traditional single-light-source hillshading.

Can I create a dynamic hillshade that changes with the time of day in QGIS?

   – QGIS does not natively support dynamic hillshading that changes with the time of day. However, you can manually adjust the azimuth and altitude parameters to simulate different times of day and create multiple hillshade layers.

What is the difference between hillshading with GDAL and SAGA in QGIS?

    – GDAL and SAGA GIS are both used in QGIS for hillshading, but they have different algorithms and capabilities. SAGA provides more advanced options, such as multidirectional hillshading and curvature-based methods, while GDAL offers standard hillshade tools with basic parameters.

How can I automate hillshade generation for multiple DEMs in QGIS?

    – You can automate hillshade generation using QGIS’s Processing Modeler or the Python Console (PyQGIS) to batch process multiple DEMs with predefined settings, streamlining repetitive tasks.

How do I improve the visual quality of a hillshade in QGIS?

    – Improve visual quality by fine-tuning parameters such as azimuth, altitude, and Z-factor, applying a smoother DEM (e.g., by using a low-pass filter), or combining multiple hillshades with different settings for a composite effect.

Can I export hillshade results from QGIS to use in other software?

    – Yes, hillshade results can be exported as raster files (e.g., GeoTIFF, PNG) for use in other GIS software or image editing tools. You can export them using the “Export” function in the “Layer” menu.

What are some common applications of hillshades in GIS analysis?

    – Hillshades are commonly used in topographic mapping, landscape visualization, archaeological site analysis, hydrology (e.g., identifying drainage patterns), and any application requiring enhanced terrain visualization.

Are there any plugins in QGIS that enhance hillshading capabilities?

    – QGIS has several plugins, such as “Relief Visualization Toolbox” and “Raster Terrain Analysis,” as well as “Batch Hillshader” which provide advanced hillshading techniques and additional terrain visualization tools, including sky view factor and multiple light source options.