[Proj] ERROR 6: No translation for Lambert Conformal Conic toPROJ.4 format is known.

Frank Warmerdam warmerdam at pobox.com
Wed Apr 1 14:52:18 EST 2009

Eric Miller wrote:
  > Frank,
> ArcGIS (9.1 at least) has "Lambert_Conformal_Conic" for U.S. state
> plane definitions and others.  All of the definitions I looked at had
> two standard parallels. 
> I'm not sure where the 1SP and 2SP stuff comes from.  The Simple
> Features Spec. for OLE (1.1) appendix 4-6 only lists "Lambert conformal
> conic."  So, the software in question is using the listed name.  The
> practice of replacing spaces with underscores in never mentioned.  The
> examples use underscores but the list of supported projections does not
> have underscores and there is no direction that underscores should be
> used or supported.


I believe the 1SP and 2SP naming comes from EPSG.  Reviewing
OGC 99-049 (SFSQL 1.1) I see it does not list many example PROJECTION
keywords.  I only noticed "Transverse_Mercator".  The list of projection
methods lists this as "Transverse Mercator", but it is not at all
clear that this list is intended to represent the keyword values.

> Thus, I think a robust WKT interpreter must accept projection names
> with or without underscores and with or without the _1SP or _2SP
> refinements. (If needed, it must look at the parameters to
> disambiguate.)  Additionally, there probably needs to be handling for
> hyphens (missing or present) and accents/non-ascii (missing, present or
> alternate spelling).  Is it "Plate-Carée" or "Plate_Caree" or
> "Plate-Carree" or "Plate_Carree" or ... ?  Only the first version is
> listed in appendix 4-6.  Perhaps it's easiest just to maintain a table
> of synonyms?

The WKT specification is grossly incomplete leaving us with such
ambiguities.  One approach is to have lots of guessing based on similar
names or lots of translation dictionaries.  I have taken the practice
instead of documenting "OGR WKT" and preparing morphing functions to
convert it to/from other representations.  The most noteworthy implementation
is the one for ESRI (Projection Engine) WKT.

I am now taking the approach that for any projection method not currently
supported in GDAL/OGR that I will adopt the ESRI PE formulation since it
is the form with widest industry adoption.  I wish I had done this sooner
(from the beginning).

I would note that CS-Map maintains extensive translation tables to convert
between the WKT represention of various software packages.

Best regards,
I set the clouds in motion - turn up   | Frank Warmerdam, warmerdam at pobox.com
light and sound - activate the windows | http://pobox.com/~warmerdam
and watch the world go round - Rush    | Geospatial Programmer for Rent

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