I make 3D height map patterns using GIMP 2.6 and the [Selection Blend] and [Mirror] scripts.
Basically I add a rounded selection blended object (lower layer) with a profiled blended object
over it (upper layer) set to screen, to create a height map. The process is somewhat involved but
here it is:
First on a new layer I draw half of a sylindrical shape using the Free Selection tool set to no
antialliasing (Can't have feathered edges on the alpha for this procedure to work properly).
Then I paste in black and set up the layer by clicking [Layer] [Autocrop Layer] to prepair for the
mirror script. The Mirrow script helps to create an exact cylinder shape on both sides.
The Mirror script doesn't work on an autocroped layer without first hiding the background layer. I
use the Mirror Script horizontally and I uncheck work on copy which stops it from popping up a new
After creating a double sided cylidrical object I then have to perform a [Layer to Image Size] on
the layer so that the [Selection Blend] script works. Then select whats on the layer by choosing
the [Alpha to Selection] function.
I have made a custom gradient that is set up to use foreground and background colors. And it is
set for Spherical Increase and Decrease to make it round. I have saved it as RoundGradient.
Then with the gradient selected, dithering unchecked, and the foreground and backround set to
default black and white, I then use the [Selection Blend] script on it which gives me this result:
Now the shape has roundness but no contour. Thus I must create a contour layer above it before
setting it to Screen layer Mode.
Next I Duplicate the layer, and within the selection I draw a regular Linear Foreground to
blackground Gradient, from black on the left edge of the selection, to white in the middle.
Then I copy this selection to the clipboard so that I can use it as a brush to smear the profile
gradient all the way accross the selection. But beforehand it is also necessary to set the
[Spacing] in the [Brush Selection] dialog box to 1 so that it will draw a smooth contour gradient.
(I wish there was a script to smear a profile gradient inside of a selection).
Note: This smear will only work out right if I have created it inside of a flat selection that has
no antialiasing or feathering. Otherwise I would be smearing an antialiased edge which would not
Now all I have to do is set this smear layer to [Screen] and it will create a rounded bump map
type of object when combined with the Selection Blend layer below it. Notice that this image below
has roundness and contour.
And this image gives me a very nice rounded cylinder when used as a height map pattern in the 3D
preview software that accompanies my 3D carving machine.
I can actually do this function pretty quickly, and the results come out remarkably well. If I
were to try and make a cylidrical object like this using 3D software not only would it be much
harder but would also take up a great deal of time.