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perliedman / shadow-mapper

Generate maps of sun and shade from OpenStreetMap data
ISC License
69 stars 18 forks source link

Using EU DEM as height data #1

Open buma opened 10 years ago

buma commented 10 years ago

Hi!

This seems like a great script. What would I need to change to use EU DEM (which is provided as geocoded TIFF) for height data?

And how accurate is this compared to GRASS's sun.hourly which seems to be great for this but I was never able to get it to work? It uses this equations.

perliedman commented 10 years ago

Hi!

The current implementation reads elevation data by using the module srtm.py - you can probably quite easily modify this implementation from a TIFF instead (or, better yet, add a new class and make it possible to use either one from heightmap.py - a pull request would be very welcome).

I haven't seen sun.hourly before, so I can't really make any comparison to it. To the best of my knowledge, shadow-mapper should be accurate and the most significant source of error is probably the resolution. Having said that, I haven't made very much of validation, so there might very well be bugs or some detail in there that I've gotten wrong.

Please don't hesitate to ask if you have further questions!

buma commented 10 years ago

Thanks. I'll look into srtm then. I'll certainly do PullRequest if I add TIFF support.

I have a couple of questions: In heightmap one parameter is projection. This is projection of height data? And in render.py you can put time as a parameter. This is UTC time?

perliedman commented 10 years ago

Sounds great!

The projection is for the output (the heightmap), yes. Times are UTC, yes.