[postgis-users] WKB data in files

Mateusz Łoskot mloskot at forest.sggw.waw.pl
Sun Nov 2 13:21:10 PST 2003


I'm a new user of PostGIS and I'm very glad that there
is such a tool like PostGIS. Great tool !

Currently, I'm working on some application
based on OpenGIS geometry. I have to make some decisions
about the data format I will use in my application.
No, I'm using ESRI Shape file and such all geometries
from Shape to my geometry model (conformed to OpenGIS spec.).

ESRI Shape seems to not to fit as well as I'd wish in my solution.

So, I think that one of many possibilities is to use files in
Well-Known-Binary format. It sounds good, but I'm not sure
if specifications gives such a possibility.
As I know, WKB is defined in order to provide (quting OGC Spec.) :
"[...] a portable representation of Geometry value as a contiguous
stream of bytes. It permits Geometry values to be exchanged between
an ODBC client and an SQL database in binary form."

So, there is no word about using geometry encoded in WKB format
and store it in binary files.

The main question is: is it possible or recommended to store
Geometry in WKB format in binary files, similar as in ESRI Shape files ?

In my opinion, it should be, but it could be hard to implement it
because of some information omitted in WKB format i.e. header for file
with information about number of geometry objects, etc. (as in Shape).
If it is possible to use WKB in files, it could be useful to 
create some WKB dumping tool. What do you think ?

Best regards


Mateusz Łoskot
mloskot at forest.sggw.waw.pl
GNU/Linux (Slackware 9.0)

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