Cities to convert

[meetar]

based on https://github.com/polygon-city/polygon-city-app/issues/48

[robhawkes]

I'll keep this table updated with data sources…

City	Licence	Format	Notes
Berlin, Germany	Licence	CityGML (LOD2)	Few, huge CityGML files
Toronto, Canada	Licence	DWG, DGN & SKP
Lyon, France	Licence	CityGML (LOD2)	Models are at block level
Hamburg, Germany	Licence	CityGML (LOD1)	LOD2 due late 2016
Montreal, Canada	Licence	CityGML (LOD2) & 3DM
Rotterdam, Netherlands	Undisclosed	CityGML (LOD2)	Validation issues during conversion
NYC, US	Undisclosed	CityGML (LOD1)
NYC, US Official!	?	CityGML (LOD1/LOD2)	A few large files
Linz, Austria	Undisclosed	CityGML (LOD2)	Lots of small CityGML files
Copenhagen, Denmark	Licence	DWG, DGN & DXF

[robhawkes]

I had a play with the new, official NYC data and the results are promising!

Unfortunately, it seems like the converter isn't working correctly for some buildings (eg. the library) but I've not put any effort in to work out what exactly is failing here but the result is that same faces are flipped. Looks like either the geometry is invalid, or the obj-conversion / repair operations are doing things they shouldn't be (like flipping faces that were actually valid to begin with). It may actually make sense to provide an option to disable validation checks and repairs as if the data is 100% valid anyway then it may produce more reliable results.

[meetar]

Yes, I noticed that too but haven't had the chance to look more closely at it. I like the idea of making validation an option, though.

On Apr 20, 2016, at 6:21 AM, Robin Hawkes [email protected] wrote:

I had a play with the new, official NYC data and the results are promising!

Unfortunately, it seems like the converter isn't working correctly for some buildings (eg. the library) but I've not put any effort in to work out what exactly is failing here but the result is that same faces are flipped. Looks like either the geometry is invalid, or the obj-conversion / repair operations are doing things they shouldn't be (like flipping faces that were actually valid to begin with). It may actually make sense to provide an option to disable validation checks and repairs as if the data is 100% valid anyway then it may produce more reliable results.

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[robhawkes]

From what I can see there are a few buildings that have overlapping geometry too which causes a lot of z-fighting, so my money is on a combination of bad / invalid geometry and edge-case issues with the converter / repair system I wrote.

Probably best to run it through val3dity and see what comes back.