Support the 4th dimension (M) in the GEOS API

[Andrew]

The GEOS API supports a 4th dimension, M, as well as PostGIS. Unfortunately Django does not and would be great if it could. I've started a ​WIP branch to see what this could look like.

[Natalia Bidart]

Hello Andrew, thank you for taking the time to create this ticket.

I've been trying to search for examples and "real life" use cases for this feature, I can see that Postgis supports the 4th-dimension but I'm not finding practical use cases to justify including this into Django. Basically we need to determine whether this would be used by niche use cases, or if this is truly something that applies to the broader ecosystem, since Django is a framework designed to offer robust and accurate solutions for common scenarios.

I'm adding as CC a few experts in this topic to see what they think, but I think the best path forward at this point is to start a new forum conversation proposing this idea. The right category would be ​GeoDjango. In there you'll reach a wider audience and get extra feedback. More information in ​the documented guidelines for requesting features.

[Tim Graham]

I asked "what is 4d geos" and AI Overview says, ""4D Geos" refers to a field within geoscience that incorporates the element of time into spatial data analysis, essentially creating a "four-dimensional" view of geological processes or environmental changes by analyzing data across both space and time; this often involves using advanced GIS (Geographic Information Systems) tools to visualize and model these dynamic changes over time, making it particularly useful for studying things like land use changes, geological formations evolving over time, or environmental impacts across different periods."

I'm not a GeoDjango user, but this doesn't appear to be a controversial feature that requires a discussion. The changes appear straightforward and it doesn't seem useful to require users to implement this functionality as a third-party package or a subclass in every project that requires it.

[Claude Paroz]

I do agree with Tim. We strive (in longer term) to replicate as much as possible the GEOS API, and this could be the next evolution in that trend.

[Andrew]

Sorry for the silence over the holidays. Would it be worthwhile for me to get my existing branch reviewable as PR with tests, docs, etc.? I'm not sure the best process to getting an issue like this merged in. I'm happy to help however is best but as Tim and Claude mentioned this is helping GeoDjango support more of the GEOS API and the primary use case for this 4th dimension if for a time component of a geometry.

[Natalia Bidart]

Andrew: yes, please! assign the issue to yourself and polish the PR. The guide for contributing can be found ​here. Let me know if you have any questions!

[Andrew]

​PR is ready for review.