Alpha Channels and Bump Maps going bad....

[Kelley]

Lately I'm getting a lot of garbage with Alpha's and Bump Maps. The artwork is clean. Regular decals go on as they should. Any thoughts? [the Albatros is an Alpha Channel, "iClapper" is a Bump.]

[robcat2075]

do you get different results with the same PRJ in different versions?

[alano]

At the risk of getting the thread deleted, this seems to be a problem with some users. Version 15f is expected to fix it. In the meantime, Nancy G. suggested decaling the entire mesh before applying any decals with alpha and this seems to work well with color. Covering all the visable mesh with the decals also seems to be important. Your bump map looks like a similiar symptom but without alpha, I'm not sure if it is the same or not. Someone suggested something along the lines of "dirtying" the white on the bump with just a little noise would help. Let us know what works out for you.

 

Alan

[HomeSlice]

In this particular case, I think all you have to do is blur your bump map. Bump maps don't work with sharp edges. The edges must be blurred, at least a little.

[Kelley]

The edges must be blurred, at least a little.

I would have never suspected that. I'll try it tonight. Thanks.

[HomeSlice]

Also, many times you don't have to use an alpha channel with a bump map. Just make the background color neutral gray (128,128,128) and there won't be any "bumping" in those areas.

[Fuchur]

Also, many times you don't have to use an alpha channel with a bump map. Just make the background color neutral gray (128,128,128) and there won't be any "bumping" in those areas.

 

I would say the alpha isnt used at all for bump-maps / displacement-maps / any kind of greyscale-image-map. Alpha-Channels are only usefull for color-maps.

All the rest will be based on the greyscale-level of an image. (0-255).

 

So 128 (or 127... this doesnt make much of a difference) should be used as neutral-level (so for example at a bump-map the 128 should be the groundlevel, everything from 0 - 127 will be lower, 129 - 255 will be higher.

 

*Fuchur*

[sir fen the usa]

i was told this will be fixed. try baking the decals. it seem to work for me.

[Kelley]

I would say the alpha isnt used at all for bump-maps....

I was not clear: The Bump Map is just that, with no Alpha. The Alpha is just an Alpha. The Iron Cross is not supposed to be raised.

[robcat2075]

Just as a technical point, alpha channels can have a use in any kind of map. An alpha channel limits what portion of a map is used.

 

In a situation where color and bump maps were derived from the same source material one might very well might have an alpha channel in the bump map that was the same shape as the alpha channel in the color map so that they would both affect the same area.

 

It's not common, but it's out there.

 

One exception is the cookie cutter map with alpha where the alpha channel is interpreted as a transparency. This is different from what an alpha channel in a color or bump map does.

[Kelley]

While we're on the subject of Bump Maps, I'm trying to use a Bump to pull up the rib shapes in the upper wing. I put down the red first, then the Bump, then changed the Bump from 'color' to 'bump' in the Properties. But the color component keeps showing through.

[NancyGormezano]

While we're on the subject of Bump Maps, I'm trying to use a Bump to pull up the rib shapes in the upper wing. I put down the red first, then the Bump, then changed the Bump from 'color' to 'bump' in the Properties. But the color component keeps showing through.

 

The color is supposed to show thru - the bump map just makes ...er... bumps - based on the greyscale values - black is indent, white is raised - neutral gray - no bump

[Kelley]

The color is supposed to show thru - the bump map just makes ...er... bumps - based on the greyscale values - black is indent, white is raised - neutral gray - no bump

I don't mean that the Red shows through, but that the b/w grayscale is showing without creating the ribs. The map used to create the bumps should not be seen. Should it?

[robcat2075]

The color is supposed to show thru - the bump map just makes ...er... bumps - based on the greyscale values - black is indent, white is raised - neutral gray - no bump

I don't mean that the Red shows through, but that the b/w grayscale is showing without creating the ribs. The map used to create the bumps should not be seen. Should it?

 

It's *possible* that the shading is fooling you, but no... a bumpmap should not produce any change in the color of the patches it is on.

 

After you are SURE that map is changed from "color" to "bump"... save, restart, reload. just to try.

 

However, for features as big as those ribs, modeling them explicitly is the way to go. Ought to be easy with splines.

[Kelley]

The color is supposed to show thru - the bump map just makes ...er... bumps - based on the greyscale values - black is indent, white is raised - neutral gray - no bump

I don't mean that the Red shows through, but that the b/w grayscale is showing without creating the ribs. The map used to create the bumps should not be seen. Should it?

 

It's *possible* that the shading is fooling you, but no... a bumpmap should not produce any change in the color of the patches it is on.

 

After you are SURE that map is changed from "color" to "bump"... save, restart, reload. just to try.

 

However, for features as big as those ribs, modeling them explicitly is the way to go. Ought to be easy with splines.

Mea Culpa. Instead of making the Wing Red color, and the Bump, as a pair and putting them into the same decal container, I applied the "Bump" as a seperate decal. No wonder the grayscale shows. Sorry.

[robcat2075]

Mea Culpa. Instead of making the Wing Red color, and the Bump, as a pair and putting them into the same decal container, I applied the "Bump" as a seperate decal. No wonder the grayscale shows. Sorry.

 

That shouldn't be a problem. Bump maps don't have to have a related color map.