AWS Thinkbox Discussion Forums

Do Maya lights' shadow options have any affect?

Krakatoa for Maya
#1

Hello,

Do the Shadows parameter options on Maya lights have any affect on rendering in Krakatoa, e.g. the Use Depth Map Shadows and Use Ray Trace Shadows options?

Thanks

#2

The “Use Depth Map Shadows” and “Use Ray Trace Shadows” settings are both treated the same in Krakatoa.

#3

That being said, the Shadow Map Size used by Krakatoa for its Attenuation maps is taken from the Light’s settings.
So you should set the lights to Use Depth Map Shadows to access and use the Resolution attribute.

  • If a light is set to Use Depth Map Shadows, then the Resolution attribute will be used by Krakatoa to determine the quality of the Krakatoa shadows.
  • If a light is set to use Raytraced Shadows, a default resolution of 512 will be used for the Attenuation map.
  • If neither Shadow option is checked, a default resolution of 512 will be used for the Attenuation map.

This is true for all Krakatoa implementations, incl. Maya, 3ds Max, and Cinema4D.

#4

Can a Maya light cast a shadow of a piece of geometry on to the particles behind it? I am not sure how the shadow map of a light affects the render in any way.

#5

Yes.

For a geometry object to cast shadows onto particles, it must be tagged as a Krakatoa Matte Object (a.k.a. Holdout, or Occlusion object) via the Matte Objects panel of the Krakatoa Render dialog
In addition, the “Use Matte Objects” option must be checked in the same panel, and the Light in question MUST be set to “Use Depth Map Shadows”.

Select the objects you want to tag, and press the button “Tag Selected Objects As Matte”. A new attribute will be added and set to true. After that, these objects will occlude both lights and camera “rays”, thus casting shadows from lights onto particles, and occluding particles behind them from the camera’s point of view (however the occluded particles can be rendered into a background layer when the Occluded Particles pass is enabled under “Render Output And Passes”, so they are not totally lost.)

Using the RGBA and the Occluded Particles pass, you can use compositing to incorporate a rendering of the geometry object into the Krakatoa rendering: docs.thinkboxsoftware.com/produ … matte.html

If a light is set to Raytraced shadows, or no shadows at all, it will NOT cast shadows from geometry onto particles, and will cast shadows from particles onto particles using the default 512 attenuation map resolution.

If the “Use Matte Objects” option is not checked, no occlusion or shadows from geometry will be produced in the scene. However, shadow casting from particles onto particles will still be computed, as it is an integral part of the volumetric rendering of Krakatoa and cannot be turned off (except by switching to fully additive shading).

#6

Thank you for your explanation Bobo!

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