In-browser singular viewshed calculations

[tombh]

I think this is possible with either using browser-native gdal or a custom Rust algorithm compiled to WASM.

From the user's perspective the worst part is potentially having to download a few hundred MBs of raw elevation data.

[johnny-salz]

here is a guy working on a project/algorithm like that https://x.com/spatialillusion/status/2048133056796442628

@spatialillusions would be great to have that algorithm integrated here

[tombh]

Woooah, that's amazing, the viewsheds are being calculated so quickly. I'd love to know more about how they're doing it.

[johnny-salz]

I hope it will be open sourced, there is mention of maplibre in the video, so 🤞

[spatialillusions]

I'm the one behind the code, and at the moment I haven't decided if I will open source it or not. As you probably are aware there is quite a lot of work to maintain a project if you don't want to ghost it completely, and I already have a bunch of projects to maintain.

You are correct in that the video mentions maplibre, and I'm using maplibre-gl-js to display the results and interact with them, but all calculations are done completely separately.

While iterating over the problem, I think that it now creates correct reaults, but I have to admit that the good performance comes partly from a lot of "cheating". You just have to do it in a way where most users won't see the cheats.

In your case, where you want to calculate viewsheds for very long distances, I'm not sure that this would be the correct way to do it.

I'll try to remember to keep you updated when I get the code in a state where I might be able to share it.

[tombh]

Hey! Well even if you don't open source it, it's still really inspiring. I imagine that even with the cheating this can be useful, like say as a basis for the user to make a decision on whether to fire off a longer correct calculation.

I'll of course keep this thread uptodate with our approach and progress.

[johnny-salz]

randomly remembered about that issue and made something -- it loads DEM and calculates viewshed and longest view in real time for every point under the mouse pointer or for central one / highest / clicked. Has your top finds as presets (calculations may differ a bit (or a lot), setting bigger grid and more rays helps). totally vibe coded in an evening.