[geovrml] Re: Is there georeference information in ArcInfo Shape files?

[Martin Reddy <reddy>]

Hey all,

I've had some great feedback on this one and thought I'd summary this for the
list. I talked to some ESRI people and heard from many of you (Rex,
Theresa-Marie, Volker, and Matthew) - thanks to all of you!

So, it appears that it is true that there is no record of anything like
coordinate system, ellipsoid, etc. in a Shape file. The coordinates may be
in some system like UTM or lat/long, but this is not defined in any machine-
readable form. Normally the shape file will come with some documentation
(e.g. html or free form text) that will define this information. 

I've heard that it may be the case that a newer version of the Shape file
format has this information included, but I know of no spec for this new
version of the file format.

So, it looks as though what we need to do in order to convert Shape to
GeoVRML is have a manual process where the user must supply the georeference
information manually.

Cheers,

Martin.


On Sat, 17 Jun 2000, Martin Reddy wrote:
> I just talked with the Matt Fadoul at Bashir Research, the guy who produced
> the ShapeViz utility for converting Shape files into VRML. He is keen to
> support GeoVRML, however he was unsure how to go about this. I have just
> looked through the Shape file format spec and there is absolutely no mention
> of how you georeference anything. No mention of coordinate systems, of
> ellipsoids, or anything that might let you place a Shape file in the world. I
> could hardly believe this!
> 
> Does anyone have any idea what coordinates are stored in Shape files? Is
> there any way to know the geographic location of the data in a Shape file or
> is this just a bag of completely unspecified numbers. In which case, how does
> this stuff ever work in the real world!?
> 
> Any help or insights would be greatly appreciated as Matt is keep to act on
> supporting GeoVRML if we can work out if it is possible.
> 
> Cheers,
> 
> Martin.

---------------------------------------------------------------------------
Martin Reddy                                   SRI International, AI Center
                                               Menlo Park, CA 94025-3493
reddy@ai.sri.com                               Tel : (650) 859-6468
http://www.ai.sri.com/~reddy                   Fax : (650) 859-3735