SSE Question about DXT1 and DXT5

[cumbrianlad]

Hi,

 

in another post I was advised that any texture should be DXT1, if not needing transparency or the likes of normal maps which obviously need an alpha channel. This sounded good to me to reduce the size of my mod. Previously I'd been saving all diffuse textures as DXT5 and reserving DXT1 for the likes of environment maps. I could shave quite a few MBytes off the mod if DXT1 is fine.

 

I've begun checking the size of the diffuse textures that I've re-done against the vanilla equivalents. So far, even though the likes of the draugr weapons (that I've re-textured) don't seem to use transparency, their file sizes are identical to mine, so they must all have been saved DXT5.

 

Once I'm finished with my greatsword, I'll experiment by taking my paint.net images for the diffuse textures and saving DXT1 to see if there's any noticeable drop in quality. In the meantime, I just wanted a few opinions on the matter. Maybe its my understanding of what I was told that still isn't quite there!

 

Thanks in advance.

[maxarturo]

DXT1 is the same as DXT5 the only difference is that DXT5 has 4 channels instead of 3 that DXT1 has, this does not affect in any way the texture/visual quality of the image itself, the actual image remains intact.

DXT1 vs DXT5 does not mean better or worse quality, they are just compresion tools that define the usage of the meshe's texture to the game engine, that's the reason they exist in the first place.

* Big screwdriver for a big screw and small screwdriver for a small screw.

You can see the effect of less system resources used by doing a simple experiment:

- In one of your cells (preferable a big cell) all textures used save them as DXT5, notice the render window stats, then save those textures as DXT1, you will see an immediate drop in the render window stats, this has an impact on how the system performs.

The only visual degrade that a texture/mesh can suffer involves the compression of the "Normal" map since DXT5 will generate "Visual Artifacts" in the normal map, if the normal map has a lot of data in it, like a lot and very fine details, this is a bug/disadvantage of the DXT compression system that causes loss of the general quality of all the textures involved in the mesh.

* this can only be seen in game and not in CK

There is a work around to this, a way to produce a flawless "Normal" map, if you are interested in this just let me know.

Edited April 20, 2020 by maxarturo

[cumbrianlad]

Right.

 

So this means that a whole load of Bethesda textures have been wrongly saved as DXT5, then! I was being guided by their canvas size and file size. It's easy to work out from that if they are DXT5.

 

I'll certainly have a go at saving some of my files DXT1 instead. Given that a 5.33 MB diffuse sword texture drops to 2.7 MB as DXT1 and I have more than a dozen textures I could easily cut 30 MB off the mod before it's put into a BSA. That's quite a chunk. Taking a look at my data folder, I'd say more like 40 MB., though by the time I cut a lot of the smaller files in half it may be more!

 

I would be interested in the 'flawless normal map' procedure, but I don't want to put you to too much effort. If the procedure can be done using paint.net as the image editing sodtware, then great. There's no rush for this, since I need to do a lot of work yet on the diffuse and environment map textures for the greatsword.

 

Thanks again, Maxarturo.

 

P.S. I followed your advice for the circlet and it's much better. Removing emissivity certainly helped. I also changed the colour of the fine detail from silver to gold and that contrasted better with the near black circlet. You can now read the dragon letters when in 3rd person.

[maxarturo]

"So this means that a whole load of Bethesda textures have been wrongly saved as DXT5"

If they just have an empty white "Alpha Channel", then YES.

Bethesda did not do a very good work with Skyrim, i guess they didn't expect that the game would have such a big success when thay were creating it, so they didn't put to much attention to it.

* Not only textures have problems, but also meshes, scripts and a bunch of other things...

* I'll write you later on today a detailed post about the "Flawless Normal" map, i need to finish with what i'm doing, finish my snack > finish the script > save > exit > reload, i don't remember by heart all the names involved.

[cumbrianlad]

Thanks Maxarturo.

 

i just checked one of the swords saving as DXT1 and it looked no different in either CK or in-game... 2.7 MB gone!

 

There's no rush for the details. I'll just appreciate whatever I can learn about making 'Normal Maps' better. Mine were distinctly sub-par but I'm improving with practice!

[maxarturo]

This will not work with an already saved texture, you need to create the "Normal Map" from the beginning and then save it.

You will need "NVIDIA Texture Tools for Adobe Photoshop" or any other tool that will have this compress format and works with some of the programms that are mostly used by modders.

If i'm not wrong there is an NVIDIA Tool for "Grimp", i don't know if there is any for "paint.net" (i have never used it).

This is highly recommended for used on textures that have a lot of details > a lot of data in the normal map, for example: in swords that have cuts, scratch, metal details, markings... etc.

Or for textures like the example from my mod that i'm posting further down, a stone wall with a hard non uniform highly detailed surface.

The only thing you need to do is after you have created your "Normal Map" and your "Alpha Channel", if your original "Normal" is 2048x2048 (2k) reduce it to 1024x1024 (1k).

And save it as:

8.8.8.8 ARGB 32 bpp / unsigned

You can still save it in its original resolution 2048x2048, but the normal will be huge, if a "Normal" saved as DXT5 has a size of 2,5mb then as 8.8.8.8 will be 10,5mb (4x), and if 5mb then 21mb and so on.

The reduce of the "Normal's Resolution" does not affect the quality of the image, always in compare with the quality you gain as 8.8.8.8, which is actually 10x from the DXT5 as you can see in the example images.

You can also see clearly that the massive increase of quality deserves to go through all the trouble !.

DETAILED STONE WALL SURFACE

- Only the "Normal" has been edited, all other textures are the same, no editing.

- There is no ENB or any other graphic enhancement running, just Skyrim engine.

- The mesh is completely flat, it has no 3d sculpturing.

Diffuse 2048x2048 > DXT1

Normal 2048x2048 > DXT5 = 10% of the surfuce details

Diffuse 2048x2048 > DXT1

Normal 1024x1024 > 8.8.8.8 ARGB 32 bpp / unsigned = Full 10x surfuce details

Diffuse 2048x2048 > DXT1

Normal 1024x1024 > 8.8.8.8 ARGB 32 bpp / unsigned

Paralax 1024x1024 > DXT1 = low high/depth

* We touch realism !.

* You will need to see the pic in full screen to be able to distinguish the massive quality fluctuation.

If you compare both images you can clearly see that the DXT5 normal has "Visual Artifacts" that degrades and blurs the diffuse and the rest of the maps even with 90% less of the surface details, while the pic with 8.8.8.8 is sharp with no blur and it actually enhance the diffuse map.

Unfortunately i don't have a DXT5 pic with full surface details so could see how much worst it becomes.

To achieve such detail all textures must be free handed, especially the "Normal Map", i don't think that any auto generate tools can do what humans can.

But even so you will still be able to see a huge increase in the quality of your meshe's texture.

I hope all of this can help you.

Edited April 20, 2020 by maxarturo

[cumbrianlad]

That is awesome!

 

Those textures look so much better... and basically for the same file size, so no increase in the mod size or more use of the resources while playing.

 

If paint.net can't support it, it may be time to move to PS.

 

I hope other people see this thread.

[maxarturo]

:thumbsup: :yes: