[OSRS-PROJ] EPSG_v65

[Clifford J Mugnier]

Gerald,

There remains the problem of associating datums with these lovely vacation
spots.  Each datum has a specific set of Grids that are correct for that
datum.  For some countries, various mathematical variations for a given
projection or Grid are dependant on particular datum date spans.
Furthermore, the EPSG "database" while extensive, is rift with errors.  The
relations and parameters for Western Europe are good.  As one gets further
and further from Western Europe, the number of errors, misunderstandings,
goofy interpretations, and outright garbage increases.

In its form as a cartographic transformation tool, PROJ4 seems to do an
excellent job.  I would strongly urge you not to contaminate it with the
EPSG stuff.

Cliff Mugnier
LOUISIANA STATE UNIVERSITY

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While doing the finishing tests for PJ_omerc I looked into the EPSG_v65
data base for some info, especially for Malaya.  Spent the weekend
learning
perl, installed the db into MySQL and everything looked rosy in spite of
weak EPSG documentation.

My question to anyone familiar with this relational data base is how to
link
an ellipsoid to a projection given a place name like Malaya?  I can
easily
find the projection associated with the area but no link to the
ellipsoid
tables.  Similarly, I can go into the coordinate reference system table
but links to datum code or ellipsoid are NULL.

What I would like to do, and this seems reasonable, is key in an area
name, do a REGEXP search of char field in appropriate table and come
up with a list of ellipsoids used in that area and a list of grid
cartographic projections.
For datum shifters, that information should be available also with the
same
basic search method.  That's probably too naïve an expectation.

These problems are the same for Borneo as well.

It is a nifty way to handle information on non-ellipsoid projection
parameters
and would seem like a useful method to use with a proj parameter DB.

Comments appreciated, including guffaws.
_____________________________________
Jerry and the low riders: Daisy Mae and Joshua
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