What are mask maps for? can they be compressed?

Since moving to HDRP I have a huge number of blue textures ending in _MaskMap.png. Why are these there and is it ok to lower the imprt resolution of them and crunchcompress?

 

When you open the mask texture, you have 4 channels
Color channel Map
Red = Metallic
Green = Occlusion
Blue = Detail mask
Alpha = Smoothness

These controls the shader properties

https://docs.unity3d.com/Packages/c...ition@7.1/manual/Mask-Map-and-Detail-Map.html

 

Before you had to use 3 different textures for PBR materials, now this is combined in one texture, where each channel (RGA) replaces these 3 textures. The Detail Mask (Blue) is to mask in/out the detail texture (which is also a mask map). If you are not using a detail texture, just leave the blue channel in your maskmap black.

 

thanks, seems to use a lot of space, am I wasting space keeping them and all the others. I mean in a 300 gig project isnt this raising it lik 150 gigs wihch it seems to do? (35000 mats).