Week 3: Shadows, Part One– Depth Map Shadows

Overview of Depth Map Shadows



Lighting Terms

  • depth map shadows
  • dmap
  • shadow map
  • shadow map resolution
  • filter size
  • bias
  • shadow map samples
  • shadow map detail
  • shadow map softness




Depth Map Shadows, dmap, or shadow map type shadows are calculated via bitmap images called depth maps. A depth map is an image or image channel that contains information relating to the distance of the surfaces of scene objects from a viewpoint. In the case of lighting, this viewpoint is the light itself.



Depth Map Attributes

Maya Software

Maya Software Dmap Attributes


Use Depth Map Shadows

Unchecked by default. An individual light in the Maya Software renderer employs either Ray Trace Shadows or Depth Map Shadows exclusively, or no shadows at all. A dmap shadow is calculated prior to the render (if not previously rendered to disk) as it is employed by the final render.



The resolution of a light’s shadow depth map. The 512 default refers to a square, single-channel bitmap image that is 512×512.


Resolution vis-a-vis Cone Angle

A wider Cone Angle may negate higher resolution


Resolution vis-a-vis Filter Size

If applying a greater Filter Size for softer shadows, strike a balance between Resolution and Filter Size. Resolution may decrease, to a degree, as Filter Size increases.


Use Mid-Dist

Mid-Dist significantly reduces self-shadowing artifacts by calculating the middle distance between shadow casting surface.


Use Auto-Focus

If on, Maya automatically scales the depth map so that it only fills the area of the light’s illumination that contains shadow casting objects.


Filter Size

Controls the softness of shadow edges. The softness of shadow edges is also influenced by the size of the shadow and the Resolution.



Offsets the depth map toward or away from the light. Adjust the Bias only if you encounter self-shadowing/light leaking problems. The slider range is 0 to 1, but you can type in a higher value. The default value is 0.001.


Disk Based Dmaps


Overwrite Existing Dmap(s)

Maya creates new depth maps, and saves them to disk. If depth maps already exist on disk, Maya overwrites them.

When you write them to disk, you get two dmaps: One is the first shadow casting surface, the other is the second shadow casting surface (calculated for ‘Use Mid Distance’)

Reuse Existing Dmap(s)

Maya checks to see if depth maps have previously been saved to disk. If so, Maya uses them instead of creating new depth maps. If not, Maya creates new depth maps and saves them to disk.



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