> On Apr 12, 2024, at 5:56 AM, Javier Jimenez Shaw via PROJ 
> <[email protected]> wrote:
> 
> Maybe you want to talk with your local agency to fix this ;)

It is not always clear as a motivated-but-unconnected individual which local 
agency and person inside it to contact to sort things out. It is also often the 
case that some government officials might not feel they have the power to 
change the license or releasability of a model. Finally, getting an official 
grid to PROJ CDN might require navigation of the procedures of a specialized 
geospatial standard body (EPSG) and standards conformance of those grids before 
official registration. 

A step-by-step process document written by people who have completed it would 
be a helpful guide of all the various starting points and steps. 

> Mainly local companies and surveyors will have an easy workflow if the needed 
> geoid model is really easy to use, better if it is automatic in their tools.

As a frequent user of grid transformations in PROJ, I do not fondly remember 
the days before PROJ_NETWORK. It is very powerful for PROJ to be able to 
conveniently compute its best transformation, apply it to the data with very 
little manual intervention, and not require the management of gigabytes of grid 
content to do it. By making it possible and convenient to be more precise, many 
software and tools across the PROJ-using dependency graph have benefitted 
greatly.

Even's COG-based GTG [1] approach for PROJ supports both an incremental network 
and a local cache distribution model at the same time. I've found it 
frustrating the OGC CRS Standards Working Group didn't value a similar approach 
when it developed the GGXF standard. Not only is GGXF content going to require 
yet another transformation for use as an incremental network, its complexity in 
comparison to GTG is going to be challenging for grid producers. 

I suspect GTG's simpler model for grid producers and PROJ_NETWORK's 
distribution channel for grid consumers will close the loop for many. The 
challenge is one is labeled a standard but has no? public software 
implementations, while the other one is unlabeled but has four years of 
implementation experience in a widely used open source software. Maybe there 
are some in the community who would support bringing GTG forward as an OGC 
Community Standard if such a label is important to them.

[1] https://proj.org/en/latest/specifications/geodetictiffgrids.html
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