[PROJ] Converting NAD83/NADV88 heights to HAE

[Greg Troxel]

Even Rouault <even.rouault at spatialys.com> writes:

> For projinfo, you need to put the PROJ string inside double quotes, and add a +type=crs
>
> projinfo "+proj=utm +zone=10 +datum=NAD83 +units=m +geoidgrids=us_noaa_g2018u0.tif 
> +type=crs"

Thanks.  I did not figure that out from reading the projinfo man page.
It says

  {object_definition} might be a PROJ string, a WKT string,  a AUTHORITY:CODE, or urn:ogc:def:OBJECT_TYPE:AUTHORITY::CODE

which I guess in hindsight sort of implies a single argument.   The
{foo} syntax makes sense in hindsight but I didn't grasp this.

I only find the +type=crs within --identify.


>> 2) It strikes me that once one moves away from basic 2D datums, the
>> legacy syntax is dangerous, and people should be encouraged to use a
>> clearer definition.  Do you agree, and if so I wonder what you think
>> should be done?
>
> The only advantage of it is its compacity, especially for simple things. Using EPSG codes or 
> EPSG names for well-known objects is an alternative. Otherwise you have to use more 
> verbose syntaxes with WKT or PROJJSON

that makes sense, but it seems that most people are using things that
can be defined via EPSG codes, and if so would be better served by
doing so to reduce confusion.

>> 3) I didn't realize one caould merge two codes that way to construct a
>> compound CRS.  That may just be me that doesn't know that, but it might
>> help to add an example to cs2cs(1).
>
> Was already documented for projinfo, but indeed wasn't explicitly mentionned for cs2cs. 
> Should be addressed by https://github.com/OSGeo/PROJ/pull/2290

Great, thanks.