Real time 3D map using WebGL

General talk
401

We can simply use the wording:
bottom:shape=* , bottom:height=* etc. In this way we could have unambiguous description of elements. It is easy to implement.

Btw.: you have a bug in the interpretation of skeleton algorithm and calculating heights of ridge and edge lines based on the highest ridge line which has the height of height=*

The point is: only the ridge line, and it is only one line in 3D building, geths this value of height. BAsed on that:

  1. Calculate angle of 2 neighbour surfaces
  2. Based on calculated angle from 1 calculate heights for next ridge lines as a vertical penetration of 2d element ridge line with the calculated surfaces.

Let´s meet. I was supervisor of the master thesis: “implementation of OSM S3DB 2.0 approach” We have done really nice things. Now we need it in OSM as well.

402

We’re using http://postgis.net/docs/manual-dev/ST_StraightSkeleton.html for skeleton (Postgis 2.1) based on SFCGAL

403

Yes, ther is the bug.

Edit: see this: http://wiki.openstreetmap.org/wiki/File:BadSkeletonAlgorithmImplementation.jpg

Above is the 1:1 implementation.

404

I’m not sure when we’ll have time to look into this :frowning:

405

It is not rocket science. Lets talk: I can explain you how to implement it. One afternoon should be enough for writing this code.

406

If you’re talking about changing the skeleton code, it’s not gonna be easy, it’s in CGAL which is used by SFCGAL which is used by PostGIS which is loaded by PostgreSQL. so even if it’s not rocket science, i have no clue what the code looks like :slight_smile:

I do understand what you want but it’s really not simple the way we’re using skeleton :slight_smile:

407

Just to give idea of straight skeleton algorithm complexity:

https://github.com/reinterpretcat/StraightSkeletonNet

This is my C# port from kendzi’s Java implementation.

408

Yes, I know. Kendzi is my good friend.
But now one question to you, eis_kalt.
Kendzi had an accident and has arm in the sling, with other words he is not able to implement new things.
We have an discussion in polish and german forum about modeling of bottom parts of buildings. The last approach is here as variant 2: http://wiki.openstreetmap.org/wiki/Roof_position

Do you think, you could enhance existing PlugIn with this functionality if Kendzi agree of course?

409

Unfortunately, I just don’t have time: all my spare time I’m spending on my project (see utymap repository for details).

Also, straight skeleton porting process was relatively easy because the logic is encapsulated in single package and I didn’t have to go into details of existing plugin implementation. For roofs, I’m afraid it is not so simple.