Ben Caradoc-Davies ha scritto: > Andrea Aime wrote: >> Ben Caradoc-Davies ha scritto: >>> Consulting with a knowledgeable stakeholder yielded these examples of >>> interesting 3D geospatial data: >>> - 3-D line-string (wells and boreholes, atmospheric and ocean soundings) >> This is 2d+1, will be handled by the proposal >>> - TIN (geological horizons) >> This could be suported as a multipolygon made of triangular 3d faces >> which are 3d polygons, but it would be not explicity, and quite a bit >> hacky >>> - Tri-surface (other geology surfaces) >>> - Solid whose shell is a tri-surface (ore-body, grade-control-surface) >> This could be supported as well the way above. But not having a explicit >> class is annoying. > > More remarks from Simon Cox: > 1. 3D line strings are not 2D+1. They often turn back on themselves, so > more than one z value for each x,y. > 2. TIN and Triangulated Surface and Solid are explicit classes in ISO > 19107 and in GML
Ok, then we have no support for them and I'm not aware of anyone putting togheter resources > Ben (as Ben, again): > > In 2D+1, is the main difference that the third dimension ignored by some > operations, such as coordinate transforms? I suspect 2D+1 will be OK for > line-strings, except when you try to change datum. Indeed. However there is no guarantee that the third dimension is going to be a Z. What if it's an M? (measured shapefiles?) The approach I'm proposing atm is assuming we don't know what the ordinates after x and y are, and keep them as is. I also tried some transformations between 3d coordinate systems when discussing this approach with Jody and they consistently failed. It seems the current referencing subsystem is not up to the task anyways. Cheers Andrea -- Andrea Aime OpenGeo - http://opengeo.org Expert service straight from the developers. ------------------------------------------------------------------------------ Crystal Reports - New Free Runtime and 30 Day Trial Check out the new simplified licensing option that enables unlimited royalty-free distribution of the report engine for externally facing server and web deployment. http://p.sf.net/sfu/businessobjects _______________________________________________ Geotools-devel mailing list [email protected] https://lists.sourceforge.net/lists/listinfo/geotools-devel
