Shadow Material

Mental Ray Material

Quickly creates shadow for a big site.
This is a really extreme case, but if you work with urban designers this may happen. This is for a big print not for an animation purpose.

If you need to do:

  • Render out shadow with alpha for an entire city scene.
  • Render size is really big like 5,000pix or higher .
  • Clean shadow edge.
  • Can’t spend a lot of time.
Render Element
Render Element
Shadow Material
Shadow Material

Using a Render Elements / Shadows, is an easy and quick way to get only shadows from a scene but it is not good for big sized renders because the edges won’t be smooth and clean. If it turns on anti-aliasing, a render time is slow. Also using a matte shadow material for the entire scene, you will get a blank image because the material can receive shadow but no cast shadow. However, we can use a blend shader to resolve this problem.

Steps

Step 1 – Make a Blend material

  • Material 1 – Arch & Design
  • Material 2 – Matte/Shadow/Reflection: Make sure Receive Shadows is turned on and Receive Indirect Illumination options are turned off.
  • Mask – Transparency: Input color is white and Transparency color is black.

Step 2 (Render Setup) – Turn on Material Override and drag the material to an empty slot (use instance) then render the scene. I used tiff file format for this.

Step 3 – Render preview is black but if click Display Alpha Channel you will see shadow.
When you bring the image to Photoshop you will see a black image again. The shadow information is under the Channels.

Step 4 – Go to Channels tab and select Alpha 1 (shadow). Select all and copy then paste under the layers tab.

Step 5 – Invert the color then change to a multiply blending mode. You should have nice clean shadow.

Download Material   Shadow Element

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Ocean Edge