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A good bump map tutorial?

Feb 12, 2012, 00:11 (This post was last modified: Feb 12, 2012 00:13 by Quickleaf.)
Post: #1
A good bump map tutorial?
In an attempt to create realistic looking moss I began following this tutorial: http://www.webdesign.org/photoshop/drawi....7780.html.
Cruising along in GIMP 2.6.11 with Paul Sherman's excellent Script-Fu & Gimpressionist plugins from http://www.gimphelp.org/script24.shtml.
So far so good.

Then I get to step 10: creating relief with bump mapping. I'm stumped. I looked for tutorials on Google, YouTube, and on Gimp Forums, but the only ones I've found have been rather confusing.

Can any Gimp pros help me figure out bump mapping? Maybe point me to a solid tutorial?
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Feb 12, 2012, 00:52
Post: #2
RE: A good bump map tutorial?
Not that hard actually. The bump-mappping process merely applies lighting effects to create visual bumps and hollows. For this it uses a "bump-map" that tells where the bumps and hollows appear. This bump-map is more or less an altitude chart, and acts a bit as an embossing plate on the target layer. In Gimp, a bump map is monochrome. Gray-50% (127,127,127) is the base level. White is the top of the bumps, and black is the bottom of the hollows. Intermediate value define intermediate levels. So for instance this bump-map layer:

[attachment=946]

Defines, from top to bottom
- bumps with sharp edges
- hollows with sharp edges
- soft bumps
- soft hollows

To apply it, you make the target layer active, and select in the dialog the bump-map layer:

[attachment=947]

You set various options (the most important is the "depth" which is the altitude delta of white and black)(the other one is the map type, but I'll let you figure it out), and you get:

[attachment=948]

Now answering your questions on
https://Gimp-Forum.net
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Feb 12, 2012, 13:36 (This post was last modified: Feb 12, 2012 13:37 by Quickleaf.)
Post: #3
RE: A good bump map tutorial?
(Feb 12, 2012 00:52)ofnuts Wrote:  Not that hard actually. The bump-mappping process merely applies lighting effects to create visual bumps and hollows. For this it uses a "bump-map" that tells where the bumps and hollows appear. This bump-map is more or less an altitude chart, and acts a bit as an embossing plate on the target layer. In Gimp, a bump map is monochrome. Gray-50% (127,127,127) is the base level. White is the top of the bumps, and black is the bottom of the hollows. Intermediate value define intermediate levels. So for instance this bump-map layer: <snip>
Ah, you're right that was easy! Blush

Now I have something that much more closely resembles moss (see below).

My next step is to overlay the moss on top of the stone floor in an organic patchy way, but I'm not sure which tool or method to use. Any suggestion?

[Image: comparison.png]
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Feb 12, 2012, 16:36
Post: #4
RE: A good bump map tutorial?
The usual method is to set you "moss" layer above the "floor" layer and set the mode of the "moss" mayer to "overlay" but other modes may give a nice effect too. You can also adjust the opacity of the moss layer to tune the effect. For a patchy look you can add a layer mask to the moss layer, and fill it with "Filter/Render/Clouds/Solid noise" that will create patches of black and white (you can further accentuate with the Brightgness/Contrast tool).

Now answering your questions on
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Feb 12, 2012, 20:12 (This post was last modified: Feb 12, 2012 20:39 by Quickleaf.)
Post: #5
RE: A good bump map tutorial?
(Feb 12, 2012 16:36)ofnuts Wrote:  The usual method is to set you "moss" layer above the "floor" layer and set the mode of the "moss" mayer to "overlay" but other modes may give a nice effect too. You can also adjust the opacity of the moss layer to tune the effect. For a patchy look you can add a layer mask to the moss layer, and fill it with "Filter/Render/Clouds/Solid noise" that will create patches of black and white (you can further accentuate with the Brightgness/Contrast tool).

Thanks again, you rock! I knew there were layer modes but I forgot how to find them.

The overlay worked well, only the moss still looks a bit too cloudy. I want to tighten the edges without sharpening the color to a brighter shade of green (you can see in the upper left square where I was playing around with burning just the edges). Playing around with Script-Fu effects to see if I can give some of the moss patches a crisper edge.

[Image: mossystonefloor_try1.png]
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