RE: [OSGeo-Discuss] multipatch shapefile FIRST_RING structure

2009-01-26 Thread Rushforth, Peter
Frank, > I would not expect to do the analysis in 3D as for my > purposes I am only interested in 2.5D geometry sets. I > believe multipatch files are normally used to represent TINs > which can be safely analysed in 2D, and the Z values just > carried along. > I guess I'm getting worked up

Re: [OSGeo-Discuss] multipatch shapefile FIRST_RING structure

2009-01-26 Thread Frank Warmerdam
Eric Wolf wrote: Frank and Peter, Maybe we we need an ogr_cleaner app that can read in poorly structured shapefiles and normalize them to the standard. Maybe even a general topology cleaner that's file-format agnostic. Sounds like a fun summer project for a CompSci student. Eric, OGR alrea

Re: [OSGeo-Discuss] multipatch shapefile FIRST_RING structure

2009-01-26 Thread Frank Warmerdam
Rushforth, Peter wrote: Hi Frank, Thanks for your response. An application that wants to process multi-patch shapefiles, including those using the FirstRing/Ring part types and that cares about nesting of rings must be prepared to do a geometric analysis to determine which are inner and oute

RE: [OSGeo-Discuss] multipatch shapefile FIRST_RING structure

2009-01-26 Thread Rushforth, Peter
Hi Frank, Thanks for your response. > An application that wants to process multi-patch shapefiles, > including those using the FirstRing/Ring part types and that > cares about nesting of rings must be prepared to do a > geometric analysis to determine which are inner and outer. This is in 3d

Re: [OSGeo-Discuss] multipatch shapefile FIRST_RING structure

2009-01-26 Thread Eric Wolf
Frank and Peter, Maybe we we need an ogr_cleaner app that can read in poorly structured shapefiles and normalize them to the standard. Maybe even a general topology cleaner that's file-format agnostic. Sounds like a fun summer project for a CompSci student. And are shapefiles really being used muc

Re: [OSGeo-Discuss] multipatch shapefile FIRST_RING structure

2009-01-26 Thread Frank Warmerdam
Rushforth, Peter wrote: > The shapefile spec for multipatch shapefiles says this: "When the individual types of rings in a collection of rings representing a polygonal patch with holes is unknown, the sequence must start with First Ring, followed by a number of Rings" (p 21). Figure 3 shows a

[OSGeo-Discuss] multipatch shapefile FIRST_RING structure

2009-01-26 Thread Rushforth, Peter
Hi, I posted the following question here: http://forums.esri.com/Thread.asp?c=132&f=1340&t=272776&mc=0 but got no response. Maybe the community will come to the rescue. The shapefile spec for multipatch shapefiles says this: "When the individual types of rings in a collection of rings represen