Workflow question

[josua]

Hi all

I am totally new to 3d zephyr, so please apologise if I will ask a few dummy questions here...

My first question is about the worflow from photos to mesh.

My workflow is probably as it should be:
1) import photos -> generates sparse pointcloud
2) generate dense pointcloud
3) generate mesh
4) export mesh

At some point, I want to cut away everything that is not part of the object. I am assuming that the best moment to do that is directly after step 1.
But I don't really know the consequences of that:
- If I delete data after step1, does this affect the quality (in a negative way) of step 2 because some of the data I am cutting could have been beneficial for the algorithms of step 2?
- If I delete data after step1, does this affect the speed (in a positive way) of step 2, 3, 4?

-> does it change processing speed of steps 2,3,4 if I cut out the object of interest right after step 1?
-> would it be better for max quality to cut away things only after step 2 or step 3 (but not after step 1)?

Thanks for your answers!
J

[cam3d]

Hi josua

I would not recommend deleting points from the sparse cloud stage (step1) as the proceeding stage will still generate a dense cloud in areas where you deleted the sparse cloud.

Deleting points at the dense cloud stage of processing will speedup the proceeding stages (variable, depending on how much is culled), seeing as you will be meshing from a small set of points, texturing fewer polygons etc...

Hope this was somewhat helpful!

[josua]

Thank you for your answer cam3d!

So the purpose of the sparse PointCloud is only to serve as a rough overview?

So would you agree that any kind of editing (e.g. deleting faces) is best done on the level of the the dense pointcloud.

Export to Mesh (or Textured Mesh) is ideally done as a last step after editing the dense pointcloud and should not require any post-editing?

[cam3d]

Hi again josua - The sparse cloud represents matched keypoints from the SFM processing and subsequently influences the MVS processing.

Here are some reference publications on the SFM (Samantha) and MVS (Stasia) stages of processing in 3DF Zephyr: https://www.3dflow.net/technology/

If you edit the dense cloud you are only ever going to be removing points, not faces, as the surface still needs to be extracted.

The editing you do depends on what your use case - I find myself editing at the mesh stage because there is no ambiguity as to whether or not the model is fit for purpose

[josua]

HI again cam3d

I really appreciate your answer!

Your SFM and MVS algorithms are really impressive..!

I was only talking about removing points in the dense point cloud before Mesh extraction. As for Mesh editing, I did not even try it inside 3D Zephyr.