Lighting Tutorials > Indoor Lighting Analysis >
Preparing the Scene

First, you will create a Daylight system. (If the model were linked or imported from Autodesk Revit, a Daylight system would already be present.) Then you will perform a test rendering to check image quality.

Set up the lesson:

- On the Quick Access toolbar, click (Open File), navigate to the \scenes\lighting_and_rendering\lighting_analysis folder, then open arena_start.max.
  NoteIf a dialog asks whether you want to use the scene’s Gamma And LUT settings, accept the scene Gamma settings, and click OK. If a dialog asks whether to use the scene’s units, accept the scene units, and click OK.

  The scene consists of an indoor tennis court. Materials have already been applied to its surfaces.

Create a daylight system:

1. On the Create panel, click (Systems). On the Object Type rollout, click Daylight to turn it on.

   3ds Max Design opens the Daylight System Creation dialog, which recommends an optimum exposure control setting for mental ray.

   Exposure Control is comparable to the shutter and aperture settings of a camera. It adjusts the brightness and contrast in a rendered image. It does not affect the actual amount of lighting in a scene.

2. Click Yes to accept the “mr Photographic Exposure Control”.
3. In the Top viewport, click anywhere over the scene and drag slightly in any direction to create a compass rose.
4. Release the mouse.

   3ds Max Design opens the “mental ray Sky” dialog, asking if you want to add an “mr Physical Sky” environment map for the background of your scene.

   Note 3ds Max Design displays this dialog only if you are using the default set of tool options. If the dialog doesn’t appear, open the Environment And Effects dialog, and in the Environment panel Common Parameters rollout Background group, click the Environment Map button and assign the shader yourself.

   To revert to this default tools settings, from the Customize menu choose Custom UI And Defaults Switcher, and on the Choose Initial Settings dialog Initial Settings For Tools Options, choose DesignVIZ.mentalray.

5. Click Yes.

   The sky map is cosmetic, and while it will create a nicely shaded background to the scene exterior, it will not affect the interior lighting levels in any way.

6. Move the mouse upward to position the sun object in the sky. The exact height of the sun in the sky is not important, as long as it is above the model. Sun height has no effect on scene lighting or rendering.
7. Click once to set the position of the sun.
8. In the Top viewport, right-click to end Daylight creation.
9. Go to the Modify panel, scroll down to the “mr Sky Advanced Parameters” rollout, and make sure Aerial Perspective is turned off.

   This option, which simulates atmospheric haze and reduces the visibility of distant objects, can interfere with lighting analysis.

Do a test rendering:

1. Activate the Camera01 viewport.
   NoteLighting analysis is always performed from a camera’s perspective, and therefore it requires a camera object in the scene.
2. From the Rendering menu, choose Exposure Control to open the Environment And Effects dialog.
3. On the Exposure Control rollout, click Render Preview.

   The preview thumbnail takes a moment or two to render. The resulting image is quite dark because the default Exposure Value of 15 is not suitable for an indoor scene.

   Render preview with Exposure Value set to 15.

4. From the “mr Photographic Exposure Control” rollout Exposure group Preset drop-down list, choose Physically Based Lighting, Indoor Daylight.

   The Exposure Value changes from 15 to 10 and the render preview thumbnail appears somewhat lighter.

5. Change the Exposure Value (EV) from 10.0 to 9.0.

   The preview updates to show the effect of the new setting.

   Specifying even lower exposure values causes the scene to appear brighter. Now you will enhance the illumination of the scene by using Final Gather to increase light bounces.

6. On the main toolbar, click (Rendered Frame Window).
7. On the Rendered Frame Window, in the Trace/Bounces Limits group (below the image area), set the number of FG Bounces to 4.

   This increases the number of times a ray of light bounces on object surfaces in a scene. Values of 4 through 7 are the most effective. Values under 4 produce less noticeable results, while values over 7 require a great deal of render time, with limited added benefit.

8. On the Environment And Effects dialog Exposure Control rollout, click Render Preview again to see how the added bounces have brightened up the interior of the model.
9. Click the Render button (or press F9) to render a full-size frame.

   Artifacts present in the scene

   The model renders well, but the shadows on the back wall, especially at the left, are too dark. There are also some dark patches on the floor of the court, to the left, that look like shadows but don’t have anything to do with the geometry of the scene.

   You could improve the render quality by adjusting the Image Precision and Final Gather Precision sliders on the Rendered Frame Window. Each slider position represents a preset group of Final Gather settings. In this lesson, however, you will perform your adjustments manually.

Use custom Final Gather settings to improve the quality of the rendering:

1. On the Rendered Frame Window, click (Render Setup).
2. In the Render Setup dialog Indirect Illumination tab Final Gather rollout Basic group, set Initial FG Point Density to 0.2, Rays Per FG Point to 150, and Interpolate Over Num FG Points to 50.

   These values will eliminate most of the noise artifacts in the scene while ensuring a reasonably fast calculation time.

   To learn more about Final Gather and each of its settings, refer to the 3ds Max Design Help.

3. On the Rendered Frame Window, make a clone of the rendered image, then render the scene again.

   This time, your image will take two to three times as long to render.

4. Compare the two images to see how your edits to Final Gather have affected image quality.

   Some artifacts remain, but the overall image is much improved.

   Artifacts reduced after adjustments made to Final Gather

5. Close the Rendered Frame Windows and all other dialogs.

Save your work:

- Save the scene as my_tennis_court_with_daylight.max.

Next

Adding a Light Meter