Re: DOQ/coordinate system precision and conventions

[Don Brutzman <brutzman@nps.navy.mil>]

Theresa-Marie Rhyne wrote:
> [...]
> perhaps we need someone from the VRML community, perhaps a VRB member,
> to tell us how to make Neil's notion happen ?

regarding coordinate systems and VRML nodes, i recommend that we

- describe conventions in common use (and provide pointers) so we 
  understand them.  SEDRIS can likely help here
- decide on convention(s) of greatest group interest
- determine floating point precision needed (likely double)
- examine two-tiered approaches to achieve double precision with multiple
  single-precision Coordinate nodes, perhaps using Locale conventions
  as developed in MERL's SPLINE/ISTP protocols, Java3D, DIS-Java-VRML,
  others, simply implemented using a Transform node convention
- implement in native VRML, demonstrate conventions for use by building
  a number of representative worlds of various sizes and scales
- implement EXTERNPROTOs which provide such nodes
- evaluate need for native VRML double precision support based on
  implemented GeoVRML worlds.  consider implementing the EXTERNPROTOs
  in native C++ using the OpenWorlds toolkit.
- compare NativeGeoVrmlCoordinate to ExternProtoGeoVrmlCoordinate
  performance using OpenWorlds toolkit or a modified browser
- produce Recommended Practices document for GeoVRML.  these could
  include suggested native implementations of GeoVrmlCoordinate for 
  browswers to provide improved performance over 
  ExternProtoGeoVrmlCoordinate.  send to VRB.
- produce recommended changes to VRML specification (such as adding a
  GeoVrmlCoordinate node) if preceding results justify it.  send to VRB.

please note that approval by an outside body, or getting extensions to
the VRML specification, are not necessary to solve any of these problems.
there are no external impediments to working group progress.

all the best, Don
-- 
Don Brutzman  Naval Postgraduate School, Code UW/Br Root 200  work 408.656.2149
              Monterey California 93943-5000 USA              fax  408.656.3679
Virtual worlds/underwater robots/Internet http://www.stl.nps.navy.mil/~brutzman