I learnt use of Bump Map from a tutorial at gug.sunsite.dk.
So, here is my try explaining it a bit more so that it becomes easy for all level users to understand the use of Bump-Map plugin, and possibilities.
Prerequisites
You must be familier with creating new image, adding new layers, deleting layers, naming/renaming a layer, filling solid color and gradient in layers/selections. If you do not know how to perform above mentioned operations then
Click here to read beginners tutorial first.
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What is Bump Map?
It is a plugin, or you may call it a filter which can be applied over a layer (
of our gimp image). It is found within the menus of the image window on position
Filters >
Map >
Bump Map...
What is use of Bump Map?
It is used to get a specific area of the layer bumped up. Or, to raise specific portions of a layer.
Simple Example
For example, we have a simple layer filled using golden Gradient, and we want to bump an elliptic (
circle) area of this layer. So before and after aplying effect, the layer is as follows:
Limitations
Any area of any layer can be bumped up using any layer as map. There are no such limitations for using this effect, but it does not make sense if you start using a transparent layer to aply bump map on another layer, or if you try bumping a transparent area of a layer.
The stacking order of layers is not important.
Recomendation
To get 100% results from this plugin, use BLACK & WHITE layers as map to use for bumping an area of other layer.
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Core Practice and Tutorial
Here we will create the same effect shown above, using the powerful plugin
Bump Map.
Follow the Steps:
[*] Start with an empty image (
File >
New), of 300x300 or any preffered dimensions.
[*] Insert New Layer and name it
Map_only.
[*] Insert New Layer and name it
Actual.
The layer
Acutal will be containg the actual image, we have to bump some area of, (
here I used only a gradient).
The layer
Map_only will be used to create the map (
The area which has to be bumped over the layer named Acutal).
[*] Select the Layer
Map_noly in layers tab, and fill it using solid white color, and select a circle region on it, using elliptic region selection tool (
The second icon on gimp main window), and fill this selection with solid black color, so that your layer looks something as below, in image window:
[*] Remove any selection, using menus in image window
Select >
None.
[*] Now select the layer named
Actual and fill it using any gradient, I have used golden with style Linear, so the image window will look as following screenshot, if layer
Actual was over all other layers:
Finally we have a layer
Map_only which cotnains a BLACK & WHITE map which will be bumped up on layer named
Atual. Order of layers in Layers tab is as below (
Although it is not important):
Now it is time to apply the Effect
Bump Map I have been talking about.
[*] Select layer named
Acutal and go through menus within image window
Filters >
Map and click
Bump Map.... A new window will appear asking you too many things, do not get confused here it is so simple. The window looks like the one below:
On top-right corner of this window there is a list of layers you have, this list is captioned
Bump map, you simply select the layer named
Map_only and click button
OK, which will immediately update the layer
Actual with a bumped circle in it.
More Adjustments using scroll options on the plugin window
Azimuth : it is simply used to adjust the light position.
Elevation : acts as contrast.
Depth : Gives more 3d depth to gumped portion if value is increased.
X/Y Offset : move the map behind actual layer.
Ambient : give/remove depth of unlightened part of bumped area.
TIP
If the layers used as map are deleted, they leave no effect over image, becuase bumped layer has already been updated. To keep the image size small delete the layers used as map.
That's it for now.
