Radiosity Controls

To set units correctly:

Follow these steps if your scene does not already use real-world units.

1. Right-click 3D Snap Toggle and on the Snaps panel, clear all the settings. Then turn on Vertex to set vertex snap. Close the dialog.

2. Choose Tools > Measure Distance to measure some object in the scene for which you know the size; for example, a door or window. The distance displays in the Coordinate Display of the status bar.

3. Choose Customize > Units Setup and adjust the Scene Unit Scale.

   For example, if your object measures 35 scene units long, and your model uses US Standard measurement, then you would enter 1 for the scale, and choose Inches from the drop-down list. This would give you an object 35 inches long.

   If your object measures 90 scene units long, and your model uses Metric measurement, then you would enter 1 for the scale, and select Centimeters from the drop-down list. This would give you an object 90 centimeters long.

Example: To process radiosity with photometric lighting:

1. Use a scene that has geometry set to the correct scale. For more information, see To set units correctly.

   For example, if the ceiling is 96 scene units high in the model, make sure the units are set to US Standard (inches) and not Metric.

2. On the Create panel, click Lights.

3. Choose Photometric from the drop-down list. (The default is Standard.)

4. In the Object Type rollout, click Target Point.

5. Drag in a viewport. The initial point of the drag is the location of the light, and the point where you release the mouse is the location of the target.

   The light is now part of the scene.

6. Set the creation parameters.

   Tip: You can use the Move transform to adjust the location of the light or its target.

7. Click Render Scene to preview the lighting.

   Make any changes you need to adjust the rendering.

8. Choose Rendering > Environment to display the Environment panel.

9. On the Exposure Control rollout of the Environment panel, choose Logarithmic Exposure Control from the drop-down list. Click Render Preview. The thumbnail preview shows the effect of exposure control.

10. On the Logarithmic Exposure Control rollout, adjust the settings until the scene lighting is acceptable. The thumbnail preview updates as you adjust settings.

    For example, a brightness of 65 and a contrast of 50 can be good values for interior scenes.

11. Choose Rendering > Advanced Lighting to display the Advanced Lighting panel. On the Select Advanced Lighting rollout, choose Radiosity as the advanced lighting type.

    The rollouts for radiosity are displayed.

12. On the Radiosity Processing Parameters rollout, click Start to begin processing radiosity.

13. Click Render Scene to render the scene after radiosity processing completes.

Example: To process radiosity with standard lighting:

Photometric lights are recommended for use with radiosity. But if you are working on a scene that already contains standard lights, you can follow these guidelines.

1. Create or load a scene containing the appropriate geometry for lighting. There is no need to adjust any scale factors.

2. On the Create panel, click Lights.

   Standard is the default choice of light type.

3. In the Object Type rollout, click a light type such as Target Spot.

4. Drag in a viewport. The initial point of the drag is the location of the spotlight, and the point where you release the mouse is the location of the target.

   The light is now part of the scene.

5. Set the creation parameters for the light.

6. Click Render Scene to preview the lighting.

   Make any changes you need to adjust the rendering.

7. Choose Rendering > Advanced Lighting to display the Advanced Lighting panel. On the Select Advanced Lighting rollout, choose Radiosity as the advanced lighting type.

   The rollouts for radiosity are displayed.

8. On the Radiosity Processing rollout, under Interactive Tools, click Setup to display the Environment panel where you set exposure controls.

   Note: The exposure controls allow you to control only the intensity of the indirect lighting. 3ds Max retains the original intensity and effect for the direct lighting.

9. On the Exposure Control rollout of the Environment panel, choose Logarithmic Exposure Control from the drop-down list.

10. On the Logarithmic Exposure Control rollout, turn on Affect Indirect Only.

11. On the same rollout, use the Physical Scale setting to assign the standard light a photometric value in candelas.

12. Click Render Scene to render the scene after radiosity processing.