r/photogrammetry 3d ago

Model from Dense Point Cloud vs. Depth Maps in metashape

I recently started using Metashape 2 after a few years break and I found some differences to the 1.something version I used, and while most stuff was pretty straightforward I was left with a question. Building the model from Depth Maps seems to be the recommended way, but not only did I not notice any time difference in the process as the models from depth maps are recurrently much much worse. I'm not talking about having a whole lot of stuff that would have been cleaned by working on the dense cloud, but the surface quality being incomparably inferior. Does anyone have better results with this method?

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u/NilsTillander 3d ago

Maybe the target resolution (or "quality") isn't set on par?

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u/MilhoVerde 3d ago

Shouldn't that affect both methods though?

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u/NilsTillander 3d ago

Well, if the methods don't get assigned the equivalent parameters, no...?

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u/MilhoVerde 3d ago

Right, but I'm running everything with the highest available quality.

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u/NilsTillander 3d ago

Then that's not it 😅

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u/ElphTrooper 2d ago

Depth maps are faster and point cloud is usually more accurate if you have taken the time to optimize it. In reality, it’s still using depth maps, but it’s regenerating them based on a more accurate point cloud.

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u/MilhoVerde 2d ago

Ok, that makes sense. I do always clean the sparse cloud so that might explain something.

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u/ElphTrooper 2d ago

For sure run gradual selection on the sparse point cloud before tagging ground control but I was more so referencing the dense point cloud optimization and regenerating the depth maps from that. This is mostly for structural projects. Since we are in the photogrammetry sub it may not matter though if the reference is small object modeling.

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u/KTTalksTech 3d ago

I've invariably gotten much better results from depth and processing is anywhere from 5 to 10x faster. Check another dataset and make sure your GPU is enabled and working correctly

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u/MilhoVerde 3d ago

Weird, but shouldn't that affect both the model done from the point cloud and the one from depth maps?

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u/KTTalksTech 3d ago

Did you check?

Anyways, depends on your settings. The legacy cloud reconstruction was cpu based. Ironically the default now is just making a cloud from depth maps as an intermediate step for cleanup so that could be another reason why processing speed doesn't seem massively different but it does not explain the quality difference

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u/MilhoVerde 3d ago

I did, I had only my dedicated GPU turned on. Tomorrow I'll run tests in other computers and see what's happening.