High quality RGBM texture compression with ASTC

Unity Engine
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1

Hi

Recently ARM post blog about fixes of Lightmap compression with ASTC asked by Unity.

Question: When we can see it in Unity? What version?

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It’s been fixed in 2019.3.0f5 and 2020.1.0a15

3

it is not

I Have Unity 2019.3.0f5 and it dont work

I have compile tool from blog and apply it to texture Texture from Blog
Results:

RawImage: ASTC 6x6

5377830--544695--upload_2020-1-16_17-25-46.jpg
5377830--544695--upload_2020-1-16_17-25-46.jpg1154Ă—891 196 KB

Processed Image ASTC8x8:

5377830--544698--upload_2020-1-16_17-26-5.jpg
5377830--544698--upload_2020-1-16_17-26-5.jpg1089Ă—889 153 KB

So it definitely not work :slight_smile:

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And even ASTC 12x12:

5377860--544710--upload_2020-1-16_17-31-50.jpg
5377860--544710--upload_2020-1-16_17-31-50.jpg1137Ă—917 165 KB

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created bug report

(Case 1212017)

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We did not integrate ARM’s solution for RGBM encoded ASTC textures yet.

The bugfix above disables RGBM encoding for ASTC LDR compressed HDR cubemaps. With this fix you should get the same results as in older Unity version such as 2018.4.

We have plans to integrate the improved ASTC specific RGBM encoder into a future Unity version, but I don’t have a specific version yet.

For now if you want RGBM encoded HDR cubemaps on mobile then please use ETC2 RGBA.

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What’s impressive is that even ASTC12x12 looks great.
Would this cube map ASTC compression processing trickle down to lightmaps too? currently light maps on iOS platform are by default PVRTC for low quality and ETC2 for medium quality but seems like there would be great storage benefits by having the option to select ASTC and which block size in there too.

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The ASTC/RGBM compression method of the original ARM blog post generates different kind of artifacts when linear filtering is used to sample those textures.
This means that at this point our effort to integrate the original algorithm is on hold.

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@florianpenzkofer I’m finding it difficult to figure out which settings to use for lightmaps targeting mobile devices. I’d like to target more modern devices, so should I set Lightmap Encoding to “Normal Quality” and use the ASTC format? (e.g. RGB(A) Compressed ASTC 6x6 block). I gather that would be ASTC/RGBM which is why I am commenting here.

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I would recommend to use ETC2 RGBA for the “_light” texture of lightmaps when Lightmap Encoding is “Normal Quality”. But it depends on the dynamic range of the lightmap whether ASTC/RGBM artifacts are visible.

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Any news? 2020.3.8f1 Bug still there(

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In 2020.3.13 the upgrade of the astc compressor was backported. It includes special handling for RGBM.

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2020.3.14 There are still some artifacts

ASTC6x6
7364984--897431--upload_2021-7-27_12-45-57.png

ASTC4x4
7364984--897434--upload_2021-7-27_12-47-39.jpg

ETC2
7364984--897437--upload_2021-7-27_12-48-7.jpg

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Do you know if the same scene looks good with ASTC in Unity 2021.2 beta?
I’m not sure if these are this is still a general problem or if something is wrong or missing in the backport.
Main reason why the ASTC changes were backported was to improve compression speed.

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Sorry for the delay. 2021.2.0b4.3123
7369220--898250--upload_2021-7-28_20-13-30.jpg

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Can you please report a bug so that we can have a look?

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Please post the bug number here when you have one.

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@florianpenzkofer

Sorry to hijack this thread but no matter what I do I can’t seem to get this encoding with cubemaps? At least in Unity 2020.3.16f1

Is there a reason? If I set to a normal 2d texture it uses RGBM but cubes are becoming dLDR

Thanks for pointers!

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There is a special case for cubemaps on mobile platforms and the related change was not backported to 2020.3.
There ASTC is still treated as “not suitable for RGBM”.
I believe you should get RGBM also for cubemaps if the Lightmap Encoding (PlayerSettings) is set to Normal Quality.
I can backport that missing change if needed.