Creating topographic "layer cake" map a.k.a. Tanaka contour in QGIS

Question

I'm wondering if there is any way to create a map similar to the image below. Basically, it would be the contours extruded, add a singleband pseudocolor ramp as the color on top, and be able to control sun direction/shading.

Typically, I have very detailed DEM GeoTIFFs, as well as vector contours to work from.

Also, is there a specific name for this type of map? I've always called it an elevation layer cake

Answer 1

Illuminated Contours, often called Tanaka Contours.

There are many different ways of creating them in QGIS. Keep in mind that quite a few of the older tutorials are now out of date as newer versions of QGIS have more styling options.

Here's a couple of very basic methods that can be set up in a few minutes. There is plenty of tweaking that can be done to produce superior outputs. If you are looking for photorealistic output, that may be beyond QGIS.

Raster Version

Starting with your original DEM, use (GDAL) Raster Calculator to calculate a stepped DEM using a formula like: 40 * round(A/40,0)

Style your stepped DEM using Hillshade.

Style your original DEM using a single-band pseudocolor, with blending mode set to Multiply.

Ensure your stepped DEM is under your original DEM in the layer order - you should end up with output like the following:

Vector Version

Starting with your DEM, use Contour Polygons (from the Processing Toolbox) to create the contours.

Style as follows:

• Select Graduated
• Set the value to ELEV_MIN and Classify
• Click on the Symbol, select Simple Fill, and check the Draw effects box

Add a Drop Shadow

This will give you something like the below:

Answer 2

You are correct -- it's called Tanaka Contours. I also found this helpful video: https://www.youtube.com/watch?v=ORvdWyGCUVQ

I will mark this as solved/answered once my permissions let me in 2 days.

Edit to add more details (hope this is allowed - credit to anitagraser.com for the functions and process).

The solution to doing this in QGIS is to first split the contours into smaller segments using Split or v.split tool. Then, you can use the Python Field Calculator to calculate azimuth of each segment using the following function: p1 = $geom.asPolyline()[0] p2 = $geom.asPolyline()[-1] a = p1.azimuth(p2) if a < 0: a += 360 value = a

After that, you can color the contours based on a function using the azimuth. The function below does it by controlling the L (lightness) of the HSL color value: color_hsl( 0,0, scale_linear( abs( (if( "azimuth" < 45, "azimuth" +315, "azimuth" -45)) -180) ,0,180,0,100) ) Then, it's simply adjusting the underlying DEM to be a discrete color ramp and playing with line thicknesses, etc.

You can also simply apply the style shared here: https://plugins.qgis.org/styles/68/