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View Full Version : bump thins out as render image size increases



Johnny
01-30-2007, 07:23 PM
I am working on a large image for a client. bump map is giving me fits. latest fit is, as the image size I am trying to make goes up, the intensity, or relief, or bumpyness of the bump map gets thinner and thinner, or less and less. the bumps look less high.

At this point, I almost don't care why, I just need to fix it so client can be happy, pay me, hire me again, etc.

I have cranked the livin' @$# out of texture amplitude, map intensity, and bump channel % (such as map intensity up to 12, texture amplitude to 200 and bump intensity to 40,000) and I am not getting what I need at the size I have to render.

clients don't want to hear that something can't be done, even if it's something we might think is ridiculous TO ask for, but I'd appreciate any help in getting this thing to work before I have to suggest to the client that they come down in size or make some other change which will result in a good-looking picture.

thanks!

J

Giacomo99
01-30-2007, 07:45 PM
It could be a lot of things--at higher resolutions it becomes more apparent that a bump map is not really "bumpy--" you might need to use actual displacement to get what you want.

If you want better feedback, you should probably post a screen cap.

Lightwolf
01-31-2007, 02:17 AM
The problem with bump maps is that they are generally very sensitive to the resolution of the base image.
The higher the res, the more detail but the less "bumpyness".
I could give you a two page summary of how they are computed, but that won't help.
In the worst case, scale down the bump image, or (untested) apply two on top of each other. A lowres one for big bumps, a hi-res one for the detail.

Cheers,
Mike

Johnny
02-02-2007, 06:15 AM
well, your comments are certainly borne out by what I see after hitting F9!

in fact, rather than a bump, what I see looks more like a very fine engraving in the SHAPE of what should be the bump!!!

think your technique would work for LW 8.5? I'm searching around here and seeing what's done in LW 9 with that node technology...

one suggestion is that mipmapping needs to be turned off.

also my map is grey and white; perhaps it needs to be black and white?

thank you!

J

Lightwolf
02-02-2007, 06:19 AM
Grey and white is fine. I haven't played enough with nodes yet to check how you can add bumps.

Using procedural textures and just one layer on top of the other (maybe with some opacity on the topmost layer, lowres on the bottom) coupled with a fairly high strength could help.
You might want to play with the blending modes as well.

I'd go into more details, but I haven't the time to check things in LW at this time, sorry.

Cheers,
Mike