[gdal-dev] Failure to convert to Airy

[Even Rouault]

On lundi 17 juin 2019 16:08:36 CEST Joaquim Manuel Freire Luís wrote:
> Even
> 
> I'm seeing this failure with the airy conversion
> 
> echo 4.897 52.371 | gdaltransform -s_srs +proj=longlat -t_srs +proj=airy
> 
> ERROR 1: PROJ: proj_create: Error -50: malformed pipeline
> ERROR 6: Cannot find coordinate operations from
> `PROJCRS["unknown",BASEGEOGCRS["unknown",DATUM["World Geodetic System
> 1984",ELLIPSOID["WGS
> 84",6378137,298.257223563,LENGTHUNIT["metre",1]],ID["EPSG",6326]],PRIMEM["G
> reenwich",0,ANGLEUNIT["degree",0.0174532925199433],ID["EPSG",8901]]],CONVERS
> ION["unknown",METHOD["PROJ
> airy"]],CS[Cartesian,2],AXIS["(E)",east,ORDER[1],LENGTHUNIT["metre",1,ID["E
> PSG",9001]]],AXIS["(N)",north,ORDER[2],LENGTHUNIT["metre",1,ID["EPSG",9001]]
> ]]' to `GEOGCRS["unknown",DATUM["World Geodetic System 1984",ELLIPSOID["WGS
> 84",6378137,298.257223563,LENGTHUNIT["metre",1]],ID["EPSG",6326]],PRIMEM["G
> reenwich",0,ANGLEUNIT["degree",0.0174532925199433],ID["EPSG",8901]],CS[ellip
> soidal,2],AXIS["longitude",east,ORDER[1],ANGLEUNIT["degree",0.01745329251994
> 33,ID["EPSG",9122]]],AXIS["latitude",north,ORDER[2],ANGLEUNIT["degree",0.017
> 4532925199433,ID["EPSG",9122]]]]' 328249.00331295 4987937.10144727 0
> 

Actually, this half works: you get the correct result, but with an error 
message.
This is because the airy projection has no code in PROJ to compute its reverse 
operation, and gdaltransform logic instanciates both forward and reverse 
transformers.
Error message, not relevant for your use case, shut off by
https://github.com/OSGeo/gdal/commit/d1b68ad5f3adc3ec8f66a4a6dac5d7655670a08c
(which also fixes a real crashing bug when trying to use the null reverse 
method)

Even

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