Making a 3D model from a bitmap in Blender

Under construction [Under construction since 6 Jan 2010.]

If you are interested in doing a 2½D mill using the Modela, you can get away with doing all of your 3D modelling in a 2D drawing program (like Inkscape or The GIMP), by using Blender's ability to convert a texture to a depth map.

For a cool application of this technique, see the light art project.

The basic idea

  1. Make a gray bitmap where luminance indicates depth. (Show bitmap)
  2. In blender we will project this bitmap onto a plane (show final result).

The details

make a gray bitmap Making a gray bitmap Software: GIMP. What to remember while doing 2D drawing: luminance maps to depth (this means that a picture that looks good in 2D will not necessarily look good in 3D and vice versa--examples);

Blender

We start by making a flat plane.

  1. Add a plane by using the [ Add | Mesh | Plane ] menu.
  2. Subdivide (128) plane.
    This puts many more vertices on the plane than the usual 4 corner vertices to ensure that we end up with a smooth mesh. If your image is large and detailed, you might want to subdivide even more. Note that this will make things slow.

Next we add an image texture to the plane. This simply associates our bitmap with the plane.

  1. F5: Shading panel
  2. Under Material panel, browse to Add New in Link to Object combo box.
    This creates a new (empty) material and assigns it to the plane.
  3. F6: Texture panel
  4. Click Add New button
  5. Rename texture
  6. In Texture type combo box select Image
  7. Click the Load button and locate your image.

Finally we use the texture as a depth map. This is called a displacement map in Blender because we are displacing the vertices on the plane by an amount proportional to the gray level in our image.

  1. F9: Editing
  2. In Modifiers panel click Add Modifier and select Displace from the menu.
  3. In the Texture edit box type the name of your texture that you chose earlier.
  4. You can use the Strength field to ajust by how much your vertices will be displaced.

You might also want to smooth your mesh. This depends a lot on the resolution of your mesh and your bitmap image. I have achieved my best results by adding two subsurface smoothing modifiers.

  1. In the Modifiers panel click Add Modifier and select Subsurf from the menu.
  2. Repeat the previous step to add another subsurface modifier.
  3. You should now see 3 modifiers list: Displace, Subsurf, Subsurf. Use the small up arrow next to one of the subsurface modifiers to move it to before the displacement modifier. You will notice that the order of the modifiers matters.
convert to mesh so that we can export to STL and import into Modela Player. Use the texture as a depth map and convert to mesh (because we need this for Modela Player). See the article on how to cut the model on the Modela.

9 January 2010