How to create a topographic profile with QGis 3.26 (Part 2)

Here’s a 5-chapter tutorial on the new QGis feature in version 3.26: elevation profiles.

Chapter 1: Profiles from vector layers

Chapter 2: Profiles from raster layers

Chapter 3: Profiles from point clouds (Lidar)

Chapter 4: Profiles layout

Chapter 5: Profiles in QField

Chapter 2: Working with rasters

The data required for this tutorial is available here.

The first difference you’ll notice compared to working with vector layers is that, when you load a raster into your project, it doesn’t appear in the profile layer panel.

For it to be taken into account in the profile window, go to Layer properties-> Elevation and check the box Represent elevation surface.

At this point, the layer is loaded into the profile window and can be used. You’ll notice that the representation is always a continuous line.

You can load as many raster or other layers as required into the profile window. Profiles are superimposed on the display, allowing you to compare them, for example.

You can use other raster formats, such as TIN

In this image we have the TIN profile represented by the green surface, the tif raster profile represented by the solid line, and the contour profile represented as points.

Use existing lines to define the profile

Instead of drawing a line freehand on the map, you can use existing lines in a vector layer.

To do this, use the tool

If we load a road network layer into our project:

UClick on a section of road to capture it and display its profile

Another type of tool is complementary and very practical:

These two tools can be used to move the profile line to the right or left, and automatically generate the profile corresponding to this movement.

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