Asteroids and rocks in Blender

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Pieced together from various tutorials around the net, which tend to be focused on rendering an asteroid. We don't want to render an asteroid, we want an asteroid mesh.

Using modifiers

Basic shape

  • Start with an icosphere. I've given mine 4 subdivisions, and made it 500m radius.
  • Add a lattice. Scale it appropriately to the icosphere - mine has 1000m edges.
  • Add a 'Lattice' deform modifier to the icosphere, and link it to the lattice. Don't hit apply yet.
  • Select the lattice, tab to edit mode, then give your asteroid its overall shape. You might want to increase the number of control points ('Object data' tab).

Surface

Now we're going to use some default textures to generate 'mesh noise' for the surface.

  • Switch to Textures panel, and create two textures, one for the fine detail, one for larger perturbations.
    • Make one 'Clouds', and increase its size. 5 seems to work.
    • Make one 'Distorted noise', and increase its size further again - say to 100 or 300.
  • Select the asteroid, and add two 'Displace' modifiers, attaching them to the textures you've just created. Adjust 'Strength' appropriately. Numbers in the 10 - 200 range seem sane for an asteroid of this size.

A quick polish

You can add a 'Smooth' modifier to make it look a bit more weathered.

Apply the modifiers

Before you make any adjustments by hand, you'll probably want to apply the modifiers you've created to the mesh.

Using proportional editing

  • Tab to edit mode, ctrl-tab to vertex mode.
  • Turn on 'Proportional editing mode' with the 'o' key. Choose an appropriate 'Proportional editing falloff' on the menu at the bottom.
  • Hit the 'g' key and scroll the mousewheel to set 'Proportional size' to 100 or so. You can now manually add some natural looking lumps by grabbing several vertices at a time.

Sculpting

Sculpting allows you to add or remove 'matter' from your model with repeated mouse strokes, like simulated clay modelling.

  • Use the mode select widget on the menu at the bottom to switch to sculpt mode.
  • Click and drag across the mesh to add
  • Ctrl-click and drag to subtract
  • Select brushes with the picture at the top of the panel on the left

Dynamic topology (Blender 2.66 or later)

Dynamic topology adds (and optionally removes) new vertices as needed.

  • 'Topology' -> 'Enable Dynamic' on the panel on the left
  • 'Collapse short edges' will remove vertices as well
  • Level of detail is determined both by the option in the panel and by zoom level

Craters and pockmarks

Haven't got that far yet, run out of polygons again... :-)

Textures and properties

Switch shading mode to 'Smooth'. tbc...

Tutorials and links

Lattice: http://www.youtube.com/watch?v=dfz0dTl7aeM Asteroid: http://www.youtube.com/watch?v=o7SdmYKirLI Rock generator script: http://wiki.blender.org/index.php/Extensions:2.6/Py/Scripts/Add_Mesh/Rock_Generator Sculpting: http://www.youtube.com/watch?v=28ZyXCHi2uo

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