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Author Topic: Texture problems with large project  (Read 3467 times)

Daniele

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Texture problems with large project
« on: July 02, 2022, 11:53:03 AM »
Dear all,
I am writing here after searching in the forum for a solution but with no success to solve my issue.
I have a very large underwater imagery dataset (2996 Gopro10 photos) which I would like to use to reconstruct a diving site. Due to its 3D morphology (flat areas, boulders, overhangs), I have both oblique and nadiral images to cover all the surfaces.  I have no problem with the alignment (all cameras aligned successfully in low quality to save processing time). I filtered and cleaned the resulting point cloud and generated two meshes: one in high quality and another by decimating it. Now the problem is the texturing process because I can't get a good texture on  mesh. I tried different mapping modes (generic, spherical, adaptive orthophoto)  after normal map generation but the results are the same. The images even if are from an action camera are all good and sharp enough so I don't think the problem is related to image quality. The model shaded looks better than the textured one. I am working on Intel(R) Core(TM) i7-7700HQ CPU @ 2.80GHz GPU(s) NVIDIA GeForce GTX 1080. Since the project Is huge (10 gigas) maybe I could upload the report to better show the workflow used. However, the size limit of the attachment is limiting for it.

 I am attaching some snaps just to better describe such aspects.

Does someone have some suggestions to solve such an issue?
Many thanks in advance for your help!

Daniele
« Last Edit: July 02, 2022, 11:55:37 AM by Daniele »

Bzuco

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Re: Texture problems with large project
« Reply #1 on: July 03, 2022, 12:21:07 PM »
Hi, how many textures did you create? Just one 8192x8192 ?...that will be probably not enough to cover all model areas and achieve original texel density like on photos.
Set the count to 2 or 3 in Build Texture dialog with the same 8192x8192 texture size.
« Last Edit: July 03, 2022, 12:31:23 PM by Bzuco »

Daniele

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Re: Texture problems with large project
« Reply #2 on: July 04, 2022, 06:42:55 PM »
Hello Bzuco,
many many thanks for your reply and solution. As you suggested, I used  8192 for the size of texture and 4 as count and now the texture is properly applied to the entire model. THANK YOU AGAIN for your valuable help!
Do you have a rule of thumb to understand how I should set such parameters according to the size of the model?

All the best,
Daniele

Bzuco

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Re: Texture problems with large project
« Reply #3 on: July 04, 2022, 07:09:31 PM »
I wrote two posts in this topic https://www.agisoft.com/forum/index.php?topic=14145.0

If your workflow is only in metashape, the fastest way how to guess the size and count is simply do one texture 4k or 8k size which does not take so much time and then compare the result with original photos. If the result looks like 4 times less sharper, then increase 4x the count or 4x the resolution...so one quick test, one quick visual guess/comparisson and then one final texture calculation :)

maurello

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Re: Texture problems with large project
« Reply #4 on: July 06, 2022, 06:29:12 AM »
I wrote two posts in this topic https://www.agisoft.com/forum/index.php?topic=14145.0

If your workflow is only in metashape, the fastest way how to guess the size and count is simply do one texture 4k or 8k size which does not take so much time and then compare the result with original photos. If the result looks like 4 times less sharper, then increase 4x the count or 4x the resolution...so one quick test, one quick visual guess/comparisson and then one final texture calculation :)

Hey Bzuco, this is an interesting topic for me too. I'd like to understand more. I usually take 4K videos underwater 3840x2160 and extract frames using Metashape. What would be the best texture resolution and count in Metashape to get the best out of the frames?

maurello

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Re: Texture problems with large project
« Reply #5 on: July 12, 2022, 08:59:16 AM »
Buzco, would appreciate guidance on this topic. You have lots of experience.
I tried to now run texture with size 3840 (same as resolution width of 4K frames) and count 8, because I used reduced overlap with 8 as surface coverage. My assumption is that Metashape retains at least 8 cameras to cover a specific surface, so I used 8 as texture count to "use all the cameras". A bit of creative assumption, if you know better, let me know.

Bzuco

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Re: Texture problems with large project
« Reply #6 on: July 13, 2022, 01:37:13 PM »
If I understand your assumption correctly, it won't work. I don't see the connection between texture count and surface coverage...also set texture according photo width...this could work teoretically only in very specific case and manually unwrapped mesh.
Before texture creating process you don't know how MS will unwrap your mesh(how many cuts, how big chunks "UV islands" will be in texture UV space, ...what will be the texel density)...so the only option is to create one test texture 4k/8k and make visual guess how many times is the texture on your model more or less sharp. And even after that guess, if you set the amount of textures, MS will unwrap your model differently, because the mesh will be unwrapped not into one(like before) but several UV square spaces....so different count/size/rotation/position/margins/... of UV islands in UV spaces.

The rest guidance(how to unwrapp in external app and calculate texel/pixel density) I mentioned is in those other posts and topic, so for now I don't have nothing better to advice  :) . From my perspective if we don't know the texel mesh density value, any calculation will be not correct. If I missed something, len me know.