Global lighting and caustics in Autodesk Maya

Correctly created shadows give realism to the image. With the help of shadow you can determine the position of the object. For example, it hangs in the air or stands on the ground. Shadows can be with sharp and blurry edges. To create shadows, the scene must contain light sources that cast shadows, surfaces that cast shadows and surfaces that take shadows.

Default shadows (none)

By default, light sources in Maya do not cast shadows. You must specify the sources that should generate the shadow. With a large number of light sources with shadows in the scene an abundance of shadows can worsen the picture and significantly slow down the rendering. If there are no illuminators generating shadows in the scene then all the surfaces facing the light source are illuminated.

Shadows based on ray tracing and depth maps

In Maya, a separate light source can not generate shadows; create them based on the ray tracing method or depth map. In one scene, you can use different types of shadows. Adjusting shadow attributes (depth maps or ray tracing) allows you to simulate different light sources that exist in the real world.

Shadows based on the depth map give approximately the same result as when tracing rays, but much faster. Therefore, do not use ray tracing without special need.

Shadows based on depth maps

Shadows based on depth maps usually give an acceptable result in most situations, significantly reducing the rendering time. The depth map is the distance between the illuminator and the nearest surface. For each light source, a rendering from its point is performed, and data on the distance to the nearest surface are recorded in each pixel of the result picture. If the scene contains a light source with a shadow based on the depth map, a depth map file (in the IFF format) is created, which contains the necessary information. In some cases, you can shorten the rendering time using the previously created map. The re-use of depth maps is described in detail below.

Shadows based on Ray tracing

Shadows based on ray tracing can be soft and transparent but require a significant increase in rendering time. When tracing rays, the path of the ray from the source (illuminator) to the destination (camera) is tracked. Use ray tracing only if you need physically correct shadows.

Usually for this there may be the following reasons:

Only for extended lighters (area light)) if the shadow should be blurred and become lighter further from the object. If you need a shadow from colored transparent objects. If the shadow should have blurred edges (although shadows based on depth maps can also cope with this task).

Warning: Shadows based on depth maps are visible when using an interactive photorealistic renderer, and based on ray tracing - no.

Capturing shadows

You can render shadows separately from everything else. This is necessary in many cases, for example, if you want to blur the shadows. The resulting shadows can be superimposed on the rendering result, making them more soft, blurry or bright, or changing their color. This technique will be described in detail below.

Mental Ray

Shadow Maps You can turn on the Shadow Maps option so that mental ray generates shadow maps.

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