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Author Topic: Deleted Dense Points Still Used for Mesh Generation  (Read 1890 times)

aloerch

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Deleted Dense Points Still Used for Mesh Generation
« on: August 31, 2018, 12:06:14 AM »
Hi,

I know this has been posted before for earlier versions, but the solutions suggested did not work. I've isolated the problem somewhat, and found a workaround, so I'm sharing it here, and hopefully it can be fixed in an upcoming version.

Version: Agisoft PhotoScan 1.4.3 (Linux and Windows both have this issue)

Problem description:

1. Delete some undesirable points from the dense point cloud.
2. I've tried both "Compact point cloud" and tried it without that option, the results are identical.
3. Choose "Workflow -> Build Mesh". Surface type Arbitrary, Reuse depth maps unchecked.
4. The resultant mesh has polygons for the entire dense point cloud, including for the deleted points.
5. To verify this, I tried deleting fully 1/2 of the dense points in the scene, and the resultant mesh still had the entire area including deleted points. I also tried deleting the sparse points, in case they were also being used for some reason, That still did not work. I tried this in linux and windows versions of photoscan and the problem exists in both. I also tried saving the project as a new file, and that did not work.

What worked:
Instead of using "Workflow -> Build Mesh" I used "Workflow -> Batch Process -> Build Mesh". I set the source type to arbitrary again, and Source Data to Dense Cloud. The resultant mesh did NOT include the deleted dense points.


This leads me to believe that "Workflow -> Build Mesh" is not using the edited Dense Cloud, but rather it is using the full dense cloud. By contrast, the batch process version does seem to use the edited dense cloud.

I hope this helps others, and I hope this gets resolved.

Alexey Pasumansky

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Re: Deleted Dense Points Still Used for Mesh Generation
« Reply #1 on: August 31, 2018, 06:35:47 PM »
Hello aloerch,

If you are building mesh using experimental (visibility consistent) method, then it is based on the depth maps, so any edits applied to the dense cloud wouldn't have any influence on the depth maps, as they are a separate product.

So if you want to generate mesh basing on the dense point cloud, then you should switch off experimental meshing method in the Advanced Preferences tab and use common method.
Best regards,
Alexey Pasumansky,
Agisoft LLC

aloerch

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Re: Deleted Dense Points Still Used for Mesh Generation
« Reply #2 on: August 31, 2018, 09:41:00 PM »
Thanks Alexey, that makes sense! I had no idea that the visibility consistent mesh option worked that way!

Alexandre Demers-Potvin

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Re: Deleted Dense Points Still Used for Mesh Generation
« Reply #3 on: February 11, 2021, 04:40:04 PM »
I've started using Agisoft Metashape 1.7.0, and I realized I also have to switch off experimental meshing to prevent deleted dense points from being part of the mesh. However, I don't see the option of switching between experimental and common meshing in the Advanced Preferences tab. Does this have to be changed with a tweak in Metashape? Besides, batch processing doesn't seem to prevent the use of deleted dense points either in Metashape. Thanks for any help.

Alexey Pasumansky

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Re: Deleted Dense Points Still Used for Mesh Generation
« Reply #4 on: February 11, 2021, 06:26:56 PM »
Hello Alexandre,

In Metashape 1.7 there are two main sources for the mesh generation: dense cloud and depth maps. Depth maps mesh generation works only for Arbitrary method, whereas dense cloud source allows to choose between Arbitrary and Height Field options.

Do you observe that the deleted points are used, when the dense cloud source option is selected? Can you confirm that it is exactly the utilization of the deleted points and not just interpolation of the holes?
Best regards,
Alexey Pasumansky,
Agisoft LLC

bransond

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Re: Deleted Dense Points Still Used for Mesh Generation
« Reply #5 on: April 16, 2021, 07:01:48 PM »
I'm having same issue. I didn't experience this issue when I was working out my workflow for this project back in December with a trial version. I'm hoping to find a resolution to speed up processing time. I'm including images of the Dense Cloud post edits and the resulting Mesh. I'm also including the settings. I used the Dense Cloud for the Mesh build and tried both Arbitrary and Height under Advanced.

For context. This plate is photographed in a container and that is what I'm trying to eliminate from the processing but it keeps showing up even though I edit it out of the Dense Cloud. I can edit it out of the Mesh but the compute cycles are wasted time.

Any advice would be greatly appreciated.

Alexey Pasumansky

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Re: Deleted Dense Points Still Used for Mesh Generation
« Reply #6 on: April 16, 2021, 08:24:13 PM »
Hello bransond,

Can you please confirm that "cloud" screenshot is related to the dense cloud? It looks more like a tie point cloud.
Best regards,
Alexey Pasumansky,
Agisoft LLC

bransond

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Re: Deleted Dense Points Still Used for Mesh Generation
« Reply #7 on: April 16, 2021, 08:47:27 PM »
Thanks Alexey,

I was editing the tie points not the dense cloud. So given that, is it possible to edit the tie points prior to making the dense cloud and limiting to the edited tie points?

Alexey Pasumansky

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Re: Deleted Dense Points Still Used for Mesh Generation
« Reply #8 on: April 16, 2021, 09:05:23 PM »
Hello bransond,

Tie points removal doesn't have direct effect on the dense cloud reconstruction area. By removing the tie points you may exclude some overlapping camera pairs from the depth maps generation procedure, if there are too few tie points left for such pair.

To reduce the reconstruction volume you can use Resize Region, Rotate Region and Move Region instruments in the Model view. Probably it should be sufficient for this project to raise the bounding box above the plate and also to shrink its XY dimensions.
Best regards,
Alexey Pasumansky,
Agisoft LLC