Using Sky Portal and Photographic Exposure Control

Rendering with mental ray: Sky Portal and Exposure Control

Hair and Cloth Tutorials

 

Autodesk 3ds Max Tutorials > Lighting and Rendering >  Rendering with mental ray: Sky Portal and Exposure Control > 

Time-of-Day Illumination

Despite having changed the wall panel material to glass, the scene is still fairly dim. In your latest render, notice how the light is cast almost directly downward, illuminating just the left-most fringe of the lounge floor. This is the result of two problems: it is high noon in Los Angeles and the architectural scene is not oriented correctly. In this lesson, you’ll change the scene so that the window is facing the proper direction: west. You’ll also reset the time of day to produce a late-afternoon ambience.

Display shadows:

To better visualize the late-day illumination, we will enable the viewports to display shadows. In versions of 3ds Max prior to 3ds Max 2008, you had to render a scene each time you wanted to view a change in shadow position. Now, you can set the viewports to update shadows dynamically as you make adjustments to your scene.

1. Right-click the Camera01 viewport to display the quad menu.
2. Choose Viewport Lighting And Shadows > Viewport Shading > Best.
3. Select the Daylight object in the scene, right-click the Camera01 viewport, and from the quad menu choose Viewport Lighting And Shadows > Enable Viewport Shadows Selected.

   These settings instruct 3ds Max to use the DirectX capabilities of your graphics card to display your scene.

Adjust scene orientation and time of day:

1. In the Top viewport, click the compass rose to select it.
2. On the toolbar, click Select And Rotate.
3. Rotate the compass 90 degrees counterclockwise.

   

   The western point of the compass rose should now point downward, so that the lounge window, where daylight illumination enters the lounge, faces west.

4. On the menu bar, click the Select Object button and select the Daylight object).
5. On the Modify panel > Daylight Parameters rollout, click the Setup button.

   

6. On the Motion panel > Control Parameters rollout > Time group > Hours spinner controls, click the up-arrow button to increment the hour setting.

   

   Note how the shadows in the lounge scene update as you change the time of day.

7. Stop incrementing the Hours value when you reach 16 (4 P.M.). Then right-click the Camera01 viewport, and press F9 to render the scene.

   

   NoteIf you prefer a brighter scene, on the Rendering menu > Environment > mr Photographic Exposure Control rollout, reset Exposure Value to 10.0.

Add final gather:

Your scene is almost ready. All you need to do now is add final gather to better distribute light entering the lounge. Final gather generates a limited number of light bounces, but is effective when producing results for initial scene evaluation.

1. Make sure the Camera01 viewport is active.
2. On the Rendering menu > Render option > Render Scene dialog > Indirect Illumination tab > Final Gather rollout > Basic group, turn on Enable Final Gather.

   

3. From the Preset drop-down list on the Final Gather rollout, choose Draft.
4. Feel free to add any further refinements you learned about in the previous mental ray tutorial, then click the Render button to render your scene.

   

   Your rendered scene should resemble this illustration.

   Compare your result by opening the scene file LoungeBar_Tutorial_Final.max.