Model shows patchwork

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#1

Hello guys, I’m fairly new to Sketchfab and photogrammetry but I have created about 30 models using various methods such as drones, DSLR and phone/iPad.

However, I have noticed that my models show a weird patchwork during the loading. It’s a bit ugly and I’m wondering if I’m missing a step on the creation process. I’m using Polycam for quickly creating a model from photos, then Blender for making corrections and adjustments and then onto Sketchfab.

I’m attaching two screenshots of a model I made to show you what I mean…

#1 is how the model looks for a sec. when I open it and #2 is the same models after a sec. when everything has loaded.

1
11080×2400 113 KB

2
21080×2400 144 KB

Here’s the link of the model:

I asked a Sketchfab employee about it and the reply was that the model has messy UVs and that’s what is probably causing it.

Is there a way to avoid those patches? And what does “messy UVs” exactly means?

Thanks for all!

#2

Hi @mikexen -

The patchwork you see is related to low res textures being loaded before the higher res textures.

If you are embedding this 3D model on another site, you can use the “preload” embed parameter:

preload

  • Default: 0
  • Account Limitation: None
  • Usage: Setting to 1 will force all resources (textures) to download before the scene is displayed.

This is useful if you want to prevent your viewers from seeing low-resolution or missing textures during the model load time. This is NOT recommended because it slows down the viewer load time (time to interaction) and is known to cause crashes on mobile devices, especially iOS

Just search for “preload” on this page for more info on that.

Regarding the ‘messy UV’ comment, let’s look at the texture file for this model (sharing a v.low res 256x256 here):
image

Can you see how the painting part of this scan is split up into different sections? The head over here, part of the body over there, etc.?

With some editing you could get all the sections of the painting into one contiguous rectangle in the texture map. Does that make sense? The same thing is true of the frame, but it’s less noticeable as this is an irregular form anyway.

Hope that helps!

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#3

Dear nebulousflynn,

Thank you very much for your reply.

I understand that the patchwork is due to low res textures uploading prior to the normal ones and that I can use the “preload” embed parameter when I want to embed the model.
However, I’m looking into eliminating the patches even when sharing the model to a partner not just when embeding it.
This has troubled me for many months now as I can’t figure out what exactly is the problem and how can I overcome it… Especially when none of the models I’ve seen on Sketchfab does that.

Any ideas?

#4

All other models on Sketchfab load in the same way, its just how the viewer has always worked.

It is the UV seams that cause the ‘patchwork’ effect. To get rid of the most visible seams, you will need to create a new UV unwrap with for your model and reproject the textures.

#5

Will I have to recreate the model from scratch you think?

Here’s another example:

This model loads without visible patches:

This model loads with the patchwork:

Could it be that I’m using glb/gltf files? Am I missing a step on Blender?
I was given a model’s .fbx and textures and uploaded them seperately on Sketchfab. When I did that, the model loads just fine. When I export a model as a glb/gltf file from Blender, then the pathwork problems are obvious.

#6

Polycam scans don’t output a clean mesh so you need to do some cleanup in Blender as @nebulousflynn mentioned. You don’t need to fully remesh it. Here is a tutorial that might help as well as a YouTube video that I find helpful (again you can skip through the decimation, remeshing steps and go to where he UV unwraps).

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