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Filesize Reduction Guidelines | Substance 3D Designer

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Overview

In some cases the total filesize of Substance 3D assets (SBSAR) can be an important factor. This page covers a few critical areas and settings to keep in mind when trying to reduce filesize.

Filesize is mostly determined by embedded bitmaps. They are files that are linked, embedded or baked and added to the Substance 3D Designer file (SBS) as a resource. Only bitmaps that are used in a graph i.e. connected to an output either directly or through the node chain are published in the Substance 3D asset. In an Substance 3D file, bitmaps have no impact on filesize, as all bitmap resources are still stored outside of the file.

Caution:

Make sure the Output size property of all Bitmap nodes are set to the Absolute inheritance method. If that is not the case, their referenced Bitmap resource will be saved at the default 256*256 resolution in the published Substance 3D asset file, which will impact the quality of one or more outputs.


Filesize Factors

There are a few different factors affecting total filesize of the SBSAR. They are listed below with an short explanation.


Filesize comparison

The table below shows the influence of all settings on each other. Bitmap used is a 4096x4096 image of generated noise, exported from Photoshop as either 24-bit TGA or JPG at quality 8. TGA's were also exported as Grayscale and RGBA mode.

The Graph just places a single Bitmap Node connected to a single output. Bitmap mode is set according to source file mode.

While the table on the right is not fully conclusive, the following can be learned when comparing visual results and file sizes:

  • Raw Bitmap + Compression Best gives the best quality with an acceptable filesize.
  • Pre-compressed source files can give reduced filesizes in most cases, but at a quality cost.
  • Smallest filesizes, but worst quality is obtained with JPG package format at quality 0.5.
  • Grayscale is not always smaller in filesize, but will have higher quality than color at similar settings.
Note:

Jpeg Bitmap Format

It's important to note that special maps that require high accuracy such as Normal maps, Vector Maps and others should probably not be set to Jpeg compression, as this will lead to much more visible artifacts!

Source image

Color TGA

Color JPG

Grayscale TGA

Grayscale JPG

Raw Bitmap Format

Compression mode: None

48 MB

48 MB

16 MB

16 MB

Raw Bitmap Format

Compression mode: Best

9.11 MB

3.37 MB

5.06 MB

4.75 MB

Jpeg Bitmap Format

Compression quality: 1

5.09 MB

1.94 MB

6.30 MB

2.49 MB

Jpeg Bitmap Format

Compression quality: 0.5

231 KB

230 KB

626 KB

569 KB

Jpeg Bitmap Format

Compression quality: 0

407 KB

433 KB

990 KB

808 KB

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