Using Hardware Shading to Preview Lighting Levels

If your computer supports SM3.0 hardware shading, you can use the Pseudo Color exposure control to preview lighting levels in viewports. This can give you quick, interactive information about the lighting in a model.

Tip: You can find out whether your system supports SM3.0-level shading by choosing main menu Help 3ds Max Resources And Tools Diagnose Video Hardware.

For the Pseudo Color results to be meaningful, your scene needs to be set up as it would be for full-scale lighting analysis: real-world units, photometric lights, valid mental ray materials, and so on. See Lighting Analysis Assistant (3ds Max Design) for the details.

Pseudo Color preview of an indoor tennis court at 3 P.M. shows adequate lighting.

For comparison, here is a rendering of the same scene.

And the same scene with an overlay of lighting analysis data

The Pseudo Color preview of the same scene at noon shows that probably artifical lights are needed.

The tennis court rendered at noon with no indoor lighting

The tennis court rendered at noon with indoor lights turned on

To preview lighting levels in a viewport:

  1. Choose Rendering Exposure Control.
  2. On the Exposure Control rollout, choose Pseudo Color Exposure Control.
  3. In the Display Range group, change the Max value to one that is reasonable for your scene.

    For example, if the lighting is primarily daylight, set Max to 65000 lux. (The default of Max=50 is not an adequate range for checking lighting levels.)

    If you already have Light Meter objects in the scene, you can fine-tune this value. For example, you might know that the daylight levels are lower than the maximum of 65,000 lux. If the scene is indoors and artificially lit, the levels will be much lower than that: usually not more than 1,000 lux. (250 lux is generally considered the minimum lighting needed for everyday use.)

    Note: In a hardware-shaded viewport, 65,000 lux is the maximum value of sunlight (or any other kind of light), because values are limited to 16 bits per pixel. This isn’t physically accurate, but it is adequate for previewing lighting levels. The viewport display will show whether daylight is present or not, which is chiefly what you need to know.
  4. Activate the viewport you want to use for the preview, click the Shading viewport label menu, and choose Configure.
  5. On the Viewport Configuration dialog Visual Style & Appearance panel, make sure you set the following options:
    • Visual Style group Set Rendering Level to Realistic.
    • Lighting And Shadows group Choose Illuminate With Scene Lights.

    It can help to increase the level of Lighting And Shadows Quality, though this slows down viewport performance.

    Note: If you use the Legacy Direct3D driver, the steps are a bit different. (This method does not work with the OpenGL driver.) The options are on the Viewport Configuration dialog Lighting And Shadows panel.
    • Viewport Lighting Options (Viewport Shading) group Illuminate Scene With group Turn on Enable Hardware Shading.
    • Global Settings (Applies To All Viewports) group Quality / Hardware Support group Choose Best (SM3.0 Option).
    • Viewport Lighting Options (Viewport Shading) group Illuminate Scene With group Choose Scene Lights.
    • Viewport Lighting Options (Viewport Shading) group Shadow Options group turn on Enable Shadows.
    • Viewport Lighting Options (Viewport Shading) group Turn on Enable Exposure Control In Viewport.
  6. Click OK.

    Now that you have set up the viewport, you can adjust lighting interactively, and see the lighting level results in real-time, or close to it. For example, you might drag the Hours spinner for a Daylight system and see how lighting levels change over the course of a day.

In the following illustrations, a Daylight system illuminates an outdoor stadium.

5 A.M.

6 A.M.

9 A.M.

Noon

3 P.M.

5 P.M.

A viewport preview of lighting levels is not a substitute for a full-scale, rendered lighting analysis that uses Light Meters. There are a few limitations.

Parent topic: Lighting Analysis Assistant (3ds Max Design)