Rollover image to view stand-ins


Stand-ins allow you to keep your working scene light and workable by deferring the loading of geometry data until render time. It is possible to add huge levels of complexity to your scene with very little effort. In this introductory tutorial, we will show you the steps required to setup a complex scene, very simply, using stand-ins.

The scene can be downloaded here.

 

The following steps introduce several useful points about using stand-ins (you might like to follow them using a suitable model of your own). Note that this tutorial is only an introduction to stand-ins, which are a very powerful tool.

Export model as a stand-in from the Arnold menu

Export Stand-in

Ass export options

Create Stand-in

Stand-in viewed as bounding box in Maya viewport

 

Load the stand-in ass file

 

Lighting

 

 

Once rendered, you should see something similar to the following image.

Stand-in lit with Ai SkyDome Light

 

Create a wood floor using the Standard Surface shader

 

So, with one instance of our stand-in geometry, you should have something like the following image.

 

Instancing the Stand-in

Move stand-in away from the center but move its pivot to 0 0 0

 

 Stand-in's instanced in a circle

 

This should result in something like the following image.

 

 

Repeat the procedure for the second row of soldiers

 

You should now have two rows of the stand-in model. Using the same method, we have created another stand-in for the standing soldier. However, the number of copies has been increased to 72 to compensate for the larger circumference.

Create and duplicate the standing soldier stand-in

 

Also, note that the standing soldier stand-in is intersecting the sitting soldier stand-ins. In this case, it does not matter as it is only his gun that is overhanging the sitting soldiers.

 

The stand-ins can be instanced many times with little overhead to rendering (the original model has around 20,000 polygons so without instancing using stand-ins the following scene with hundreds of soldiers would be quite large). Arnold, of course, has no trouble rendering the scene.

 

Conclusion

It's worth pointing out that this introductory tutorial has only covered the basics of using stand-ins. For example, as well as using .ass archive files, stand-ins also work with pre-compiled custom procedural programs which you can provide in the form of a dynamic library, allowing you to use parameterized procedural geometry. Stand-ins can also be recursive, and you can defer loading of the procedural geometry until it is needed during rendering (i.e., the geometry is not loaded, and uses no memory, until a ray enters the object's bounding box). These techniques make it possible for you to assemble scenes in a modular way.

 

You can see the creative potential that stand-ins can give you. Below are some further examples that will hopefully inspire you to create your own. Have fun with stand-ins!

 

Thanks to Angel Jiminez for the use of his facial co-ordinates

For more details about stand-ins in MtoA see the main MtoA stand-ins description.