[PROJ] What is the syntax for a vertical datum change?

[Ulises Ibarra]

Hello:
Continuing with the attempt to change from ellipsoidal heights to
orthometric heights. I executed the instruction:

echo 578174.247 3593725.312 1295.083 2010.0 | cct +proj=pipeline +step +inv
+proj=utm +zone=11 +ellps=WGS84 +step +proj=utm +zone=11 +ellps=WGS84
+proj=vgridshift +grids=/nubes/geoides/GGM10_GEO.gtx
  578174.2470   3593725.3120     1295.0830     2010.0000

But there is no change in heights. Could you tell me what I'm doing wrong,
please?

The file GGM10_GEO.gtx is the Mexican Gravimetric Geoid of 2010.
I don't know what the current era of the ellipsoid would be, for this
reason I assumed one: 2010.0

El vie, 15 mar 2024 a las 10:51, Ulises Ibarra (<
ulisesmartinibarra at gmail.com>) escribió:

> Mr. Even, thanks You very much.
>
> El vie, 15 de mar de 2024, 1:42 a. m., Even Rouault <
> even.rouault at spatialys.com> escribió:
>
>>
>> Le 15/03/2024 à 06:27, Ulises Ibarra via PROJ a écrit :
>>
>> Hello:
>> I am trying to change the vertical datum of a LIDAR LAS file. But first I
>> must understand the syntax of proj, but I can't understand it.
>>
>> If I use the following expression:
>> echo 747194.732 2307402.892 2037.133 | proj +proj=vgridshift
>> +grids=C:/clouds/geoids/GGM10_GEO.gtx
>>
>> "proj" is a legacy tool only for 2D cartographic projections. You want to
>> use cct instead: https://proj.org/en/9.4/apps/cct.html
>>
>> -- http://www.spatialys.com
>> My software is free, but my time generally not.
>>
>>
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