[OSRS-PROJ] EPSG_v65

[Gerald Evenden]

First of all, I would not contaminate PROJ.4 with any data base
system (other than what it already has with ellipsoid references, etc.).
I was only looking for a convenient relational data base system
as a source for proj parameters.  Everything so far is pretty much
been the flat file approach.

I also understand the hassles related with ellipsoids and datum
specs but it would seem like simpler cases such as Alaska
Zone 1 for NAD83 and NAD27 ought to cough up the ellipsoid.

Yes, I agree that there are errors within the system.  I have found
one code that points nowhere but does seem to contain a projection
code.

The system did cough up the projection parameters for Malaysia
sans the ellipsoid which I can read from an old fax.

After working with the well constructed USDA Nutritional data base I
assumed something better than what I got.

On Feb 17, 2004, at 8:01 PM, Clifford J Mugnier wrote:

>
>
>
>
> 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
>
> -----------------------------------------
>
> 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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