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Polycounts

C. Sven Johnson

September 08, 2016 21:19

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What are the recommended polycounts for various 3D assets? For example, number of triangles (or quads) for a handheld item (small), a ride-on item (medium), and an architectural item (large); both the visible mesh and the collision mesh.

4 comments

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  Widely Linden September 08, 2016 23:46

  Thank you for the question it's a tricky one!  Assuming you want your content to run well in VR building in an efficient manor is key and that means being mindful of your poly counts.  

  The intent of the scene you are building should ultimately inform how you allocate your polygon budget. For instance, you may have a sparse gallery space composed of only a few hundred polys and it contains half a dozen small sculptures.  Since the sculptures are small in size one might assume that they should keep the count on them extremely low, say less than 1000 faces. However, if the intent of the scene is to allow users to pick up these objects and inspect closely in VR it may be reasonable to push the poly counts as high as 50,000.  

  I know this isn't a satisfactory answer.  Instead of specific poly counts for a given size range I would recommend these rules of thumb.

  1. Use the fewest numbers of polys required to communicate the form of the subject reasonably well.  This is doubly true for physics shapes.  Mesh decimation tools are your friend!  Get aggressive with your reductions.  Normal maps can work wonders!
  2. Try to keep your scenes total poly count under 3 million (give or take...).  You may be able to get away with more with clever layout and use of occluders.
  3. Build scenes with plenty of occluders (objects that block ones view).  In other words try to arrange your spaces such that you can't see everything from everywhere.

   

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  C. Sven Johnson September 09, 2016 04:47

  Appreciate the quick response and understand what you're saying; however, I'm thinking in terms of modeling items which may be used by others in their experience design; general guidance for general use. Perhaps it's too early for that, but this leads me to wonder if asset details will be listed in the Store; everything from render and collision mesh polygon counts to texture types and sizes; enough information - and perhaps even a custom metric based on a number of different considerations - to help people make informed decisions.

  And thanks for the rules of thumb. In particular, the ~3 million limit is good to know.

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  cesar January 06, 2017 03:41

  What is better to have, polycount, or normal maps? If I fill the space with a lot of normal maps, how many could that be? What is better?
  
  

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  Jason January 10, 2017 01:07

  Cesar,

  Short answer between poly count or normal maps is both! You need both properly applied. Here's a good rule of thumb -- save your polys for capturing the silhouette and use normal maps for the details that minimally deviate from that silhouette.  OR Polys for the outside and normal maps for the inside.

  For VR normal maps can look good.  If the deviation you are trying to portray with the normal map is to great it will look flat when viewed in VR.

  thanks,

  Jason