How to create a shaded relief map of a mountain range in Luzon, Philippines

I made this map in April 2020 but as another GIS expert said, “put your stuff out there!”

This guide will only cover Northern Sierra Madre. Apply the steps to the other mountain ranges (even outside Luzon) and it should work. There are a lot of nuances that I encountered when making this map and I won’t include everything.

1. Get Digital Elevation Model (DEM) from EarthExplorer

a. Go to EarthExplorer and create your account
b. Under the Search Criteria tab > Polygon > Use Map > set the extent of NSM which is something like this

If you will only use a single tile, use the ‘Add Coordinate’ function instead of ‘Use Map’

d. Under the Data Sets tab > search and tick SRTM 1 Arc-Second Global
e. Under the Results tab, you will see tiles which belongs to, click Show Browse Overlay and it will show 7 tiles on top of the basemap. You only need 6 so disregard the bottom most tile which is the first result or SRTM1N15E122V3 and download all 6 tiles. I used the GeoTIFF option.

2. “Stitching” the tiles in QGIS

Now you have all 6 DEM tiles that cover the entire NSM, you need to stitch them together. You do this so you will be only working with a single tile instead of multiple.

Your canvas should start like this. I added OpenTopoMap so you can see that the tiles are correct.

To stitch, click Raster > Miscellaneous > Build Virtual Raster > un-tick Place each input… > input 0 in Nodata values(s)…

By making all cells with value of 0 as ‘no data’, the algorithm removes it and will result to a clipped DEM

3. Hillshading/styling the DEM

As described in a tutorial on the same topic by BNHR:

A hillshade provides users an immediate appreciation for the surface topography, providing depth to a 2-dimensional map, which makes it easier (even to those untrained in cartography) to interpret features on the map (e.g. valleys, hills, mountains, etc.).

As I’ve said, this guide will not cover every nuance of my process. However, when I made the map, hillshading my map took me a long time. When I followed the tutorial, I ended up with this:

When I ticked Multidirectional, the DEM became black. I have no idea why but I solved it by doing the following steps:

a. Reproject the virtual raster to WGS 84 / UTM zone 51N (just change it in the layer’s Source tab.

b. Click Raster > Warp (Reprojecect) > set Source CRS to WGS 84 > set Target CRS to WGS 84 / UTM zone 51N

c. The result should look like this, just like what’s shown in the BNHR tutorial. I just followed the tutorial’s instruction by setting Z Factor to 2, tick Multidrectional, and select Cubic and Average for Resampling.

To style it, you need to duplicate the DEM. One will serve as the hillshade and the other as the “colored raster”.

d. Duplicate the DEM and rename the layers as “hillshade” and “colored”. The latter should be on top. The purpose of this is to provide color to the hillshade. Think of it as a mountain range made from recycled paper and painting it to make it look real.

e. Change the Render type of your colored layer to Singleband pseudocolor > click the Color ramp, select Overlay as Blending mode and apply the following

Position 0%: 0, 120, 0 RGB
Position 28%: 89, 86, 0
Position 47%: 119, 75, 0
Position 60%: 146, 110, 49
Position 74%: 173, 146, 101
Position 100%: 255, 255, 255

And it should look like this

When I first did this, the output relief looked too pale for me and I didn’t like the ground was green instead of brown

From here, I spent a lot of time tweaking the color ramp to make it look more “forest-y”. This is where I learned the most and I definitely should have took notes or saved the color ramps.

I may edit this part to add that process, but this should give you a good starting point on making your relief maps. Thank you for reading!

Thanks to Open Source Options, BNHR, and GeoHipster’s interview with Lyzi Diamond :D

You can see me on LinkedIn, OpenStreetMap, and GitHub