GLTF Size

T

tpitman

0
I have a scene that I am exporting to a GLB. It works good except its size is really large.

The scene has several flat panes with images on them. If I take the total size of all the images they are only 11MB. When I export the GLB file it is 23MB.

Is there any way to make the GLB file closer to the size of all the images files combined?

I am trying to upload this as part of a decentraland project and they have a size limit of 15MB.
 
Hi.
glb has a texture quality export property at Cheetah3d´s Preferences which can decrease the file size drastically.
Another method to "vaporise" image file size is to use ImageOptim.app.
To get an impression of how it impacts file size I made a screenshot before and after of a folder containing 6 PNGs + GLB file:
200115-0001.jpg

200115-0002.jpg


GLB Export image quality 1 vs 0,5:
200115-0003.jpg


Hope this will help with your project.

Cheers
Frank
 
Thank you for your reply.

There must be something wrong with the preferences setting. I changed it to 0.5 and exported and the file size stayed exactly the same. I then tried 0.1 and got the same results.

I tried changing both the glb and gltf and it didn't affect things at all.

Any idea why that might be? I have checked for updates and have the latest version of Cheetah3D (7.4.1).
 
I also used the ImageOptim app and it saved 1MB our of 10.5MB. That is good, but didn't help with the final glb file size. That file is still 21.5MB for some reason even thought the total size of all the images is only 9.5MB now.
 
So I decided to uncheck the box for embedding the images. Now the entire thing is a size I would expect of about 10MB. It will make for a harder deployment, but gets the job done.

Any idea why I can embed the images in the glb and have it be the same size?
 
I used the default settings with 1 and 0,5 image quality and the screenshots show very clearly the changed resulting file size. I have no clue why it's not working for you. I used png images and did not expect such a drastically shrinking file size either with ImageOptim nor changed export settings - but it works as you can see.
To eliminate anything else could you probably make your Cheetah3d file available?

Cheers
Frank
 
Such a big difference in file size is quite strange.

The gltf/glb exporter doesn't always recompress the images. If your color/bump textures are .jpg or .png files the exporter uses the original data without recompressing to maintain their full quality. So such textures should cause a file size increase.

The texture quality property is mainly used for the ARM (ambient occlusion, roughness, metalness) texture which is created on the fly during export and encoded as JPEG. Do you have various such textures in your scene?

Do you possibly use the same texture for various different materials? Maybe Cheetah3D embedded them multiple times?
 
Frank helped me privately and figured out that I had a texture on a model that was in a different folder that I had forgotten about. It was 10MB all by itself.

Once I made that one smaller everything now makes sense and is an expected size.
 
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