Would you like global contour + hillshading datasets?

[aschleck]

Hi, neat project!

A while ago I generated global contour (vector, zoom 9-14, imperial and metric, glaciated, 915gb) and hillshaded (raster, zoom 9-12?, 443gb) tiles for my project https://trails.lat. You can see them at that link or inspect the contours here: https://stevage.github.io/vector-inspector/#?url=https://tiles.trailcatalog.org/contours/12/665/1445.pbf&loc=9.94/47.5063/-122.0151

I've gone back and forth on releasing them given it was a lot of work to generate them (though the code is open source here https://github.com/aschleck/trailcatalog/tree/c4a9e95acefed61fde06192fc273cf7cc9c17636/java/org/trailcatalog/importers/elevation/contour), but maybe this project is the right way to do it.

Would you want them?

[hyperknot]

Wow, this looks amazing! Terran maps is one thing I'd really like to include, however I don't yet have too much experience with them.
How does this relate to using Terrain RGB tiles?

[aschleck]

I assume by terrain RGB you mean DEMs (digital elevation maps). In those layers you have a mapping from pixel to latlng where the value of the pixel encodes the elevation (note that with TIFF images you can do single channel 32-bit float values so it's not 3 channel RGB). My layers are generated from DEMs, though the tiling scheme for the source data I'm using (mostly Copernicus from the EU, some NASADEM) is not the standard zxy scheme so they are different.

I was separately working on generating a global zxy RGB DEM tileset but ran out of energy because I didn't desperately need it and the tooling I was using was being stupid.

There are very clever client side implementations that can generate contours (idk if they're vectorized, maybe) and hill shading rasters from zxy RGB DEMs at render time, however I decided to pregenerate them server side into actual tilesets. In my experience messing with hill shading, the gdal (the program I use to do the shading) implementation just looked visually better than the shader I wrote (my shader looked smoothed and weirdly shiny? gdal looks more real). Since I have implemented my own alternative to MapLibre it's possible that's just a flaw in my own code. Implementing contouring client side in my renderer seemed both too hard and also like an excellent way to crash mobile devices. Also my contour vector layer encodes when a contour is over a glacier (it's pretty!) and it's doable but bonus complexity to calculate that client side.

Not sure if I answered your question. I think it's good to have all three and I personally think they're orthogonal even though you can do everything from one DEM tileset at render time.

[hyperknot]

I made an issue about it, can you copy your reply there?

[hyperknot]

Let's move to an issue here: #19