Mipmap black "halo" problem

[Ancient]

What could cause this?

http://img441.imageshack.us/f/xrengine201009181438057.jpg/

I use Ps4, Nvidia DDS 8.23 plugin, DXT1 1bit alpha compression.

 

[Davros]

sorry what are we looking for ?

 

[Ancient]

Bush textures. Mipmaps that don't fade correctly.

 

[Simon F]

Isn't the fading more likely to be done with "fog"?

If, OTOH, you are using filtering on DXT1 textures with on/off alpha, then you should treat those as pre-multiplied alpha, i.e. use a blend of (1, One_Minus_Src_Alpha). (Refer to Messrs Porter, Duff and Blinn for details).

 

[Ancient]

This?

http://www.td-grafik.de/ext/xfrog/alpha/index.html

 

[Simon F]

This?

http://www.td-grafik.de/ext/xfrog/alpha/index.html

Err... I don't think that explanation is correct. The following for example, is completely back-the-front:

As the possible range of the alpha channel is limited to the maximum brighness of the color

May I suggest you read the following instead?:

• Porter & Duff: "Compositing Digital Images".
• Blinn: "Compositing - Theory" (especially the section on filtering)
• Willis: "Projective Alpha Colour".

Cheers
Simon

 

[HAL-10K]

Most LOD systems for foliage objects blend between the levels by using noisy 8-Bit alpha data.
Simply look at the original data of this game.

 

[Barbarian]

I use Ps4, Nvidia DDS 8.23 plugin, DXT1 1bit alpha compression.

Is the original DXT1 as well?
You have to be careful with DXT1, since transparent areas will also be forces to black.
You need to mipmap from a full color texture (32bit) which has fill-color (for example some average green) under the transparent bits.

 

[Simon F]

Is the original DXT1 as well?
You have to be careful with DXT1, since transparent areas will also be forces to black.
You need to mipmap from a full color texture (32bit) which has fill-color (for example some average green) under the transparent bits.

Read the Jim Blinn reference I linked (in particular the section on filtering) and you should see that, rather than being a problem, it should actually be a benefit. FWIW I used to think the same way.

 

[Panajev2001a]

Read the Jim Blinn reference I linked (in particular the section on filtering) and you should see that, rather than being a problem, it should actually be a benefit. FWIW I used to think the same way.

Are we talking about the pre-multiplied alpha (composited colors) in that paper by Blinn?

I found this to be a nice read on the subject too (although in blog form ):
http://home.comcast.net/~tom_forsyth/blog.wiki.html#[[Premultiplied%20alpha]]

 

[Ancient]

Is the original DXT1 as well?
You have to be careful with DXT1, since transparent areas will also be forces to black.
You need to mipmap from a full color texture (32bit) which has fill-color (for example some average green) under the transparent bits.

Yes, original is also DXT1. Almost all foliage textures (grass, bushes, branches) are DXT1. I can solve this problem with DXT5, but in that case mipmaps disappear to early.

Btw, by default all foliage textures in this game have black background, so that could be the problem.

And thanks for all the answers.