Render layers example: automotive preview

Consider an example of a preview image for automotive design. The idea is to make the image look as realistically-lighted as possible, while also providing color choices for the car model. As well, it should be easy to change the background image for a variety of looks.

This can be accomplished in Maya and image-editing software using render layers.

In Maya, this scene has a variety of reflective surfaces and environment lighting placed around it for optimum rendering.

While working on the scene, a variety of layers are created and previewed. The final image is saved out to PSD layered format. For more details on saving to PSD layered format, see Render layers to PSD format. The final image contains nine composited layers:

There are two Beauty layers, one showing the car model with a red color, and the other showing a blue color. This can be easily done in Maya by switching the material assignment on the car objects per-layer. This allows you to quickly and easily create final images with a different car color, as all other layer contributions to the final image are the same.
There is a black background image (easy to replace). The beauty and background layers are ordered properly with the Normal blend mode so the beauty layers appear ‘on top’ of the background image.

There are luminance depth, shadow, occlusion, and specular layers created using the Maya render presets. Each contributes to the realistic lighting of the image. For more details on these presets and how they affect the final rendered image, see Work with layer presets:

Finally, there is a reflection layer, that is combined in image-editing software with a geometry matte layer to produce a reflection only where the car does not cover it.

The final image shows very realistic lighting as the various passes contribute their effects: the specular layer makes reflections and glow more prominent, the occlusion layer creates realistic darkening in crevasses and under geometry, and the luminance depth layer darkens parts of the image that are farther away from the camera. The shadow layer adds shadows to the car image and around the image. Finally, the reflection layer adds reflections to the model.