On Fri, Mar 4, 2011 at 7:57 PM, Howard Butler <[email protected]> wrote: > As an aside, I have written up some language for WKT for the next LAS 1.4 > specification that I hope is adopted. > See http://liblas.org/development/wkt.html for more information, and I'd be > interested in any feedback folks might have.
Seems entirely reasonable; Geotiff's CRS stuff is mysterious to me, so i'd be happy to see LAS move to something that is ... um, well known. > Another aside is that E57 explicitly supports polar coordinate systems > http://libe57.org/ You might look there for options too. I did check out E57 a while back (the format, and the library). Here are my notes from then: The Good: 1. The low-level format is described fairly well. 2. The basic approach (blobs, with XML text afterwards) is unusual, but reasonable. 3. Depending on how its used, it could be very storage-efficient. 4. It's very, very flexible. 5. An open-source implementation library is generally a very good thing to have. Minor issues with the library: 1. No Mac support. #if WIN32 [] #elif defined(LINUX) [] #else #error. 2. More overhead than seems necessary - i.e. the massive Xerces library, the full set of systems headers on Win32, just to read a point cloud. 3. The E57Simple sample shows some rather strange usage, e.g. point colors as double *colorRed, double *colorGreen, double *colorBlue. The example has 22 fields _per point_. I can only hope that it's valid to leave the majority NULL. Issues with the format: 1. Although the low-level format and vector/chunk types are documented and library-supported, the valid ways in which they are composed in the file is /not/ public information. "The standard will be available for purchase via the ASTM website." Probably not a big deal for some companies (which could just join the E57 committee of the ASTM), but still. 2. The format is SO flexible that that there is a large danger to interoperability. Like many other historical formats (VRML, GML, IGES come to mind), it may be easy for a dozen apps/vendors to read/write "E57", yet be unable to correctly read anyone else's E57 files. My conclusion on E57: wait and see. If the high-level format becomes a bit more open, like with some sample files or actual demo code that writes a conformant file in a reasonable way, then maybe. Right now, LAS is looking more promising. -Ben _______________________________________________ Liblas-devel mailing list [email protected] http://lists.osgeo.org/mailman/listinfo/liblas-devel
