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title: "Best Practices - Modeling"
canonical: "https://rmanwiki-27.pixar.com/space/RU/608829441/Best%20Practices%20-%20Modeling"
format: markdown
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# Modeling
When creating assets, it's essential to understand which objects fall into specific categories and model their detail accordingly:
**Hero assets**** **
Things like main characters and the focus of a shot or a story
**Set assets**
These may have varying levels of detail based on where they are in a scene. Close-up items may need more details.
**Props**
These are often kept as simple as possible. You'd be amazed at how good texturing can take a low-detail asset and make it look quite nice!
## **RenderMan is designed to render subdivision surfaces** when possible for animated characters and hero objects. This reduces possible tearing and improves the look of characters and organic objects seen up close. This is also a good choice when using displacement.
Polygons like to come apart when displaced, so convert to a Subdivision Surface.
When modeling for Subdivision Surfaces, keep these things in mind to get the shape you want but not destroy performance:
- When converting to a Subdivision Mesh using the default Catmull-Clark scheme, to avoid over-dicing, use quads only. This means all your faces have four sides. Avoid triangles and N-sided faces.
- Only model the bare minimum detail you need in the base mesh so that the resulting surface is the correct shape when subdivided and not more.
- Keep creased edges to a minimum; they can be expensive.
- Make use of higher micropolygonlength settings. This provides automatic level-of-detail, and higher numbers are coarser but can still be enough to look good. Try settings anywhere from 1.5 to 3 for reasonable production quality. (Note that if this is too coarse you will get shading artifacts especially along edges, reduce the value slowly. Anything less than 1 is *very high* quality.)
Polygons are also quite useful for anything with hard normals (faceted faces for many inorganic things like buildings, props, set pieces, etc.) You may soften these normals for closer rendering or add more modeling details to make it look nice, but be aware that silhouette artifacts may appear during shading if that's insufficient.
But despite these caveats, polygons for background and prop objects will render just fine and perform quite well. These objects are typically not deforming and are plentiful in your scene.
Making these subdivision surfaces can balloon your memory usage for little visual impact.
Make use of bump mapping instead of displacement on polygons or convert them to subdivision surfaces for displacement.
When laying out your UVs, avoid overlapping UVs and keep an eye on UV shells with flipped edges, as this can cause artifacts when displacing or warnings during the render.
> ℹ️ Our texture caching mechanism can handle filling the scene with high-quality textural details and looks, but we need the whole scene geometry to trace against to live in memory. By being careful with your modeling choices, you can fit quite a lot into your scene and render many, many gigabytes of textures at once.
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### Next Steps
Now you’ve learnt about the best practices for modelling and how RenderMan subdivides your geometry at render time, let’s move on to introducing you to the PxrSurface.
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