Hi Andrea, Thank you for your time!
On 08/12/2012 04:09 PM, Andrea Aime wrote: > There is a mix of things that confuse me a bit here: > * the method in the transformation is purely 2D anyways, you won't get > a 3D envelope out of it (it samples the 2D perimeter of the original > bounds > to make an accurate transformation) > * it may be legit to transform a 3D bbox into a 2D one, because maybe you > are integrating it with some 2D data, the proper way to go from 3D to 2D > should be a MathTransform. The method in ReferencedEnvelope3D uses the 2D transforming method, only looking at the first 2 dimensions, and getting a 2D envelope back, but then just restores the third coordinate so it stays the same and actually does return a 3D envelope. Proper 3D transformations is one of the challenges we face with the 3d integration. > Makes sense, but makes me wonder at the same time, what happens if you > return a 3D geometry instead? I guess you had something break? The problem is to make a proper geometry of a bounding box, you will need a three dimensional polygonal surface, to represent a cube. If I understand correctly, there is no support for this kind of geometries in geotools atm and it is basically a whole new JTS that needs to be written for this kind of support. At the same time, I think there might be other, more efficient ways to translate the 3D bbox query to sql. > In general, given your experience with your proposal, what would you > say are the > missing bits/steps to work on (outside of this proposal) to make 3D > data and queries > really work? > Well, the vividsolutions JTS library does support a third coordinate but in practice it only has support for 2D complex structures and algorithms. This is the biggest problem. I think to make 3d fully operational, I think we almost need to rewrite the whole JTS library. Regards Niels ------------------------------------------------------------------------------ Live Security Virtual Conference Exclusive live event will cover all the ways today's security and threat landscape has changed and how IT managers can respond. Discussions will include endpoint security, mobile security and the latest in malware threats. http://www.accelacomm.com/jaw/sfrnl04242012/114/50122263/ _______________________________________________ GeoTools-Devel mailing list GeoTools-Devel@lists.sourceforge.net https://lists.sourceforge.net/lists/listinfo/geotools-devel
