The Dangers of Overly Large Files

Matthew Yetter
Matthew Yetter

ZBrush is well known for its ability to handle massive polygon counts. In fact, any given SubTool can be subdivided as high as 100 million polygons.  However, just because one can do a thing doesn't always mean that one should.

When a model reaches dizzying polygon counts, several issues can arise:

  1. File Size: When SubTools approach 100 million polygons, the file size can balloon to over 6GB. This is not just a storage issue but also affects the performance and stability of both ZBrush and any software you might be trying to transfer the model to.
  2. Performance: Handling such a large amount of data requires significant computational resources, including using a lot of virtual memory. This can lead to slow performance, crashes, or even failure to load the model in other software suites.
  3. Compatibility: Not all software can handle such a high-density mesh efficiently. This can lead to unexpected errors during the transfer process, as the receiving software struggles to process the excessive amount of detail.
  4. Render and Animation Issues: If your goal is to render or animate the model, a mesh with this many points will likely cause severe slowdowns and potentially compromise the quality of the final output.
  5. Unnecessary Detail: Often, the level of detail in a high-density mesh is not visible in the final product, especially if it's for animation or gaming. This means a lot of the computational effort is spent on details that don't add value to the final product.
    • Put another way, a 4K texture map has ~16 million pixels.  Even an 8K map (which many applications can't use) is less than 68 million pixels.  If your model has more points than your map will have pixels, you have sculpted and/or painted details that can't even be output from ZBrush.

To resolve these issues, here are a few recommendations:

  • Reduce Mesh Density: Consider using decimation tools within ZBrush to reduce the number of points without significantly compromising the visible detail. Aim for a balance where the model maintains its integrity but with a more manageable point count.
  • Split into Multiple SubTools: Four SubTools of 25 million polygons each have the same amount of detail as a single SubTool of 100 million polygons.  However, it will be much easier for your computer to work with, improving performance and reducing risk of corruption or other issues.
  • Optimize for Intended Use: Tailor the level of detail to the specific needs of your project. For instance, if it's for gaming, lower poly counts are generally preferable.
  • Use Normal or Displacement Maps: To export from ZBrush and maintain detail without the high poly count, consider baking the details into normal maps. This technique allows you to preserve the appearance of high detail on a lower-poly model.
  • Test Frequently: Regularly export your model to the target software suite during your modeling process. This helps ensure compatibility and performance are maintained throughout your workflow.

By addressing these issues, you'll improve the manageability of your model and ensure smoother interactions with other software, ultimately leading to a more successful project.

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