Wednesday’s eclipse happens very low on the horizon across most of Europe, so the practical question is not “how much of the Sun is covered” but “is there a hill, a building or a forest between me and it”.
I built a small free tool to answer that, and OSM data is the heart of it: buildings and forests fetched from Overpass, extruded over Copernicus terrain, with the eclipse computed minute by minute (Espenak/NASA Besselian elements) and the cloud forecast overlaid. Single self-contained HTML page, everything client-side.
Building heights use height / building:levels where tagged, with a neighbor-based estimator otherwise: so well-tagged areas look noticeably better, which makes this accidentally a nice visualization of tagging quality. If your area looks wrong, I’d genuinely like to know.
(And to be transparent about load: it queries public Overpass mirrors, with local caching after first load. If Wednesday gets busy, dense areas may be slow — apologies in advance to the mirror operators.)
Thank you so much for this feedback: precise, actionable, and exactly what I was hoping for.
You are right about the French tooltip on the reload button; I found a few other strings that had escaped translation as well. A fix is being deployed. Same for the mirror usage concern: the app will move from parallel requests to a staggered fallback, to stay well within the operators’ policies. Apologies to them indeed, and thanks for flagging it.
About the eclipsed Sun not being hidden by buildings: that is definitely not intended, and my own tests never showed it. I would be very grateful if you could tell me where you observed it. The coordinates (visible in the URL after the #) or simply the place name would let me reproduce and fix it properly.
Totality duration in the summary: great suggestion. The contact times are already computed internally, they just aren’t displayed yet. I’ll add it in the next update.
As for the source code: everything runs client-side, there is no server component at all. The simulator is a single self-contained HTML page (Three.js + Leaflet), so viewing the page source in your browser gives you the entire program, free to reuse.
And I’m really glad it already helped you find a better spot. That’s exactly what this tool is for!
Thanks! I was going to have a stab at doing something along these lines, as I thought it would be fun finding out how to do it. I knew we wouldn’t get a good view from our hotel. Unfortunately, my partner discovered that we could reserve a table at a seafront bar with what should be a perfect view, for less than the price of a kidney. My motivation evaporated
Also, repository is nice as you can see also edit history.
But obviously you are not obligated to freely license it, I mentioned it because you may be publishing it as “all rights reserved” (applied automatically unless clearly specified otherwise, and “free to reuse” is sadly not a clear license) and not doing it deliberately.
See http://choosealicense.com/ (though note it is made by corporation and pushing corporation-friendly MIT over AGPL)
and this tool contributed to this success - thanks!
(note: in reality corona was much larger, more lights were seen, including colorful ones from airport and it was a bit less dark)
also, I shared it with another OSM mapper who changed location of their group as it indicated they would not have seen eclipsed Sun from the initial planned location
Danke! 
. Echt super.
