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Bumpmapping



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A nice 3D looking effect can be made for images by Lighting effects or bumpmapping. Tentatively I'm telling you about lighting effects only.
There are less images in this tutorial than normally in my tutorials, because it represents slightly more advanced usage of The GIMP. The main reasong, though, is that my server space is running low. :P

Bumpmapping requires two layers. The first layer defines the surface of the bevelled object and the second one defines the profile of the object. The surface of course shows as it is in the result, but since The GIMP isn't primarily ment for 3D graphics, has the third dimension be made differently. That's what we need the other layer for, which shall be called bumpmap. It's grayscale, and the lighter area, the higher it will be. Black will be the lowest area or transparent (will be chosen later), and white will be the highest.

Now that you've got the idea, we can get to work. Let's create a golden text.

First the bumpmap has to be made.
  1. Paste the text to be beveled on the black layer. The text must be white.
  2. Select alpha. Right-click the name of the text layer in the layer dialog, and click Alpha to selection. Then we'll contract and feather the selection a bit.
    Select -> Contract
    Contract half of the size of the bevel you want. If you want to create a bevel of 6 pixels, contract the selection by 3 pixels. Then feather it.
    Select -> Feather
    Set the value to the size of the bevel you want. So I choose 6 pixels.
  3. Select the black layer, and fill the selection with white.
  4. Now, if you want, you can adjust the profile for you bevel..
    Layer-> Colours -> Curves
    You can picture the curve as the edge of the bevel. See the table in the bottom of the page to see the result of different curves.
The bumpmap should now look like this (image cropped):
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Now we'll create the surface.
  1. Create a new document or layer on the previous project. Same size.
  2. Create clouds on this layer
    Filters -> Render -> Clouds -> Solid noise
    Size around 2,5 - 2,9, Detail 1 and tileable.
  3. A hint of gaussian blur.
    Filters -> Blur -> Gaussian blur
    About 5-10 pixels, no big deal.
  4. Select the gradient named as Golden.
  5. Colourize the clouds with this gradient.
    Filters -> Colors -> Map -> Gradient map
Here's the timeline:
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Now we've got the surface. Let's put them all together...
  1. Create a new document/layer. Again, the same size. This has to be empty.
  2. Filters -> Light effects -> Lighting effects
    First, tick Transparent background, if you want. It makes every black areas in the bump map alpha. Next, click on the Bump map -tab. Tick Enable bump mapping and select the Bumpmap image. Maximum height defines how high the white areas will be. Usually very low values, like 0,02 suit best. You'll find information about Curve later in this tutorial.
    Then click the Environment map -tab. Tick Enable environment mapping. Select the surface layer/document ass the Environment map.
  3. Now you can adjust the direction of the light. The blue dot in the preview represents the source of light. Drag it anywhere you like. In the Light tab you can adjust the light more accurately. In Material tab you can choose how the object reflects the light. You'll find your settings by trying. Then click OK.
Well now, you've got something there. I hope you like it. =)


Here's a table in which you can see how different Color curves and bumpmap curve types affect the result. Color curves are shown in columns, bumpmap curve types in rows.
Translations:
Lineaarinen = Linear
Logaritminen = Logarithmic
Sini = Sinusoidal
Pallomainen = Spherical
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What do you think? Let me know! (Tutorials are rated as 10 being the best)

-Peltzi

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