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I have imported a heightmap (mountain) from world creator and used the color map as a material.

enter image description here

I want to apply a cell fracture to it, to make the mountain break into a bunch of pieces. However, the cell fracture causes some weird effects. It turns the mountain into a cube and usually, the machine stops working at that point. Seems like the computer can't cope with the task but it has actually some really good components. So I'm wondering what's wrong. Thanks for your help.

The settings of the Cell Fracture add-on are Source Limit 150, Recursion 1. Pretty basic.

Blend File

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  • $\begingroup$ Can you add more details such as the cell fracture settings, how many pieces are a "bunch of pieces" (10? 100? 500, 5000?). And what does the mountain looks like? Is it a solid manifold object or a plane with displacements? And how many vertices has it? $\endgroup$
    – Blunder
    Oct 2 at 18:46
  • $\begingroup$ @Blunder I have Source Limit 150, Recursion 1. Pretty basic. I have added a link to the file I'm working with. Thanks $\endgroup$
    – Christoph
    Oct 3 at 8:44
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The more than 429,000 vertices are too many for most computers to process.

I would create a low-poly version of this model and blow that one up.

The mesh topology does not matter because the mountain will not be deformed. So we can use a Decimate modifier to bring the vertex count down to 21,474 and the number of faces to 41,734. That's roughly 21 times fewer vertices.

  • duplicate the mountain, don't move it for the bake, just hide the original one
  • add and apply a Decimate modifier: method Collapse and a Ratio of 0.1
  • UV unwrap the model (I used method Smart UV Project)
  • bake the Normal (in Cycles, use bake option [X] Selected to Active, Extrusion: 5 m (enter the value)
  • and bake the Diffuse map. For Contributions check only [X] Color
  • if you want to texture the inner faces of the fragments create another UV Map and call it "UV Map inside" or so. Create another material for the inner faces and use the created UV map with a UV Map node. The UV map will be changed by a UV Project modifier later. In the Cell Fracture settings, set Material Index to 1 (that's the second material slot)

Use the baked images and you will have a mountain that looks exactly like the high-poly one but it's low-poly. This one you can use for the Cell Fraction add-on. Your settings created 254 pieces still took a minute or two. Be patient.

fragments

The inside of the mountain looks a bit weird. It's because the created fragments are not properly UV unwrapped. You can use a UV Project modifier with 4 Empties to texture the inner faces. The use menu Object > Link/Transfer Data > Copy Modifiers to copy the modifier to all fragments. (video: Blender 2.64 Tutorial - Cell Fracturing Part 2 (Texturing))

To apply all the modifiers of all selected fragments use Object > Convert > Mesh (related question: Is it possible to apply modifiers to multiple objects at once?)

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  • $\begingroup$ man! I really appreciate it. that's just a perfect manual. Thank you! $\endgroup$
    – Christoph
    Oct 5 at 20:10

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