added capability to generate vector polygon of the raster extent

[lucadelu]

Fix #1825

Do you need any test for this?

[pierotofy]

It looks good, thanks @lucadelu

Can you please describe in more details the use case for needing this extent file? I don't have a problem merging it, but I would like to understand which use case we're solving (the information is redundant, so why is it needed?)

[lucadelu]

It was a request of a client, for what they told me, to get the right positioning and resolution of a raster in a CAD system they need to upload a vector layer and later tell to the raster to adapt to the vector polygon loaded before.

Since they would like to have DXF, in the last commit I also added DXF output, the sum of the two is something like 120Kb and it is really a fast operation.

[pierotofy]

Ok, I understand, but should ODM be in charge of generating redundant files for an unspecified CAD software?

It's a rhetorical question, I'd be nice to hear @smathermather's thoughts on this.

[smathermather]

I've been following, and as far as the geopackage with the extent, I think we need to make explicit what CAD package we are supporting for 2 reasons: users of that CAD package should know we support them and we should be at least announcing that support in the pull request and thus the releases; and we should know we are supporting them so that when we get bug reports later because we changed something that breaks that support, we will want to know where those questions are coming from and why. Maybe we can even prevent those breaks from happening, if there is some downstream community engagement.

As far as the DXF file, that feels like custom code bolted on to a core project, and don't feel inclined to support its inclusion. I could be swayed, but from what little signal I get in this request, I don't even get the sense the upstream customer knows why they want it, which definitely sets off my this is custom code warning flags.

[lucadelu]

@smathermather ok I understood, what is not clear to me is, geopackage is it fine and not the DXF or you are incline to not support the inclusion of both of the output?

[smathermather]

I would just say: choose one and let us know who we'll now be supporting as a CAD community. Choose the one that better serves your use case, and anyone who needs the data in an additional format will need to post-process.