Rendering Tip - Balance Lighting

Balance Lighting to Finish Your Renderings

Did you know that you can use the Light Balance interface while your rendering is processing?

You don't have to stop a rendering to adjust lighting. Instead, use Light Balance to change image brightness and make other lighting adjustments. You can do this even while your rendering is processing. Use the IRender nXt Light Balance dialog to improve the lighting for your rendered scene and complete more renderings for your client presentations, in-house design reviews, and proposals.


Balance Immediately or Later - It's Up to You

Fine tune the lighting solution for your renderings while the images are processing, immediately after each is finished, or even later.
If your preference is to balance lighting while your renderings are being processed, just keep in mind that only a fraction of the lights are solved during each rendering pass, so it's a good idea to let the rendering complete a reasonable number of passes before you make changes.
If you balance lighting when the rendering is completed, start the Light Balancer to modify lighting.


When you save the completed rendering as a 'nxtImage' file, you can open the image later to balance the lighting.



Open nXtImage File

Use Get nXtImage on the toolbar to open a nXtImage file for editing.


A saved nXtImage includes light channels data which allows the Light Balance interface to modify lighting for fixtures grouped together on any of the eight available light channels. Modifications include switching channels on or off, and brightening or darkening light emitted from the fixtures.


You can balance lighting at any time, while processing, immediately after, or later.
For example, when I evaluate the lighting solution for my rendering I realize that the image is very bright and the lighting is too harsh.

Use Light Balance to open the Light Balancer dialog.


A Brief Orientation to this Dialog

  • Channels to use (1-8): - Light Channels to list on the dialog. This may not include all channels used in the model.
  • Reset - Restore original values to each Light Channel.
  • OK - Remove dialog and save changes.
  • Overall Brightness - Image brightness
  • 0:Sun - SketchUp Sun. Assigning fixtures to channel 0 always means automatic assignment, thus 0 is not literal when lights are added to the model.
  • 1:Sky - SketchUp Sky. Lights assigned to channel 1 will share the channel with the SketchUp Sky.
  • Light channels 2 - 7 - Open to assignment. Please note that channel 4 is the glow channel. Lights assigned to channel 4 share the channel with self-glow objects or materials.
  • Lock Luminance - Check to enable Ambient Lighting (general image brightness) changes. Uncheck to retain Ambient Value (may produce unexpected results).
  • Ambient Light - The value is calculated while rendering. When a nXtImage opens, the displayed value will be 0.
  • Use for Animation - Preset the Ambient Value for all images generated for an animation.

Note: Names default to the type of fixture in most cases, however it is possible to set the names as I have done.

Overall Brightness

The first adjustment I made was to lower the overall brightness of the image from 50 to 45.
HERE'S AN IMPORTANT TIP: When you open a nXtImage file, change the image brightness before you do anything else. This lets the image editor reset the ambient baseline (general brightness) for the image and synchronize each Light Channel.



Light Channels

The spot lights are too bright, the desk lamp is too dim, and once I have these adjusted I'll evaluate the ceiling lights. First I'll dim the spot lights.
Dim the Spot Lights



Brighten the Desk Lamp
The shade on the desk lamp is set with a self-glow. Self-glow does not emit light. I'll brighten the self-glow channel and also the actual lamp. Once I've done this I notice that the desk lamp reflection in the window is much better than before.



Dim the Ceiling Lights
The recessed can lights in the ceiling can be dimmed to further soften the lighting.



Brighten the Sky
With the other lighting adjustments taken care of, now I think that the sky is too dark, giving the impression that the clear glass in my window is tinted. The focal point of this room is the custom window, so by brightening the sky I can also emphasize the beveled glass.




Lighting solutions are complex and it's very difficult to guess at the final rendering while an image is processing. When materials are rendering properly and the concern is limited to lighting, the shortest path to a presentation quality rendering is to use the Light Balance Interface to adjust lights. This can be done while the rendering is processing, immediately afterward, or even later using a nXtImage file.
Don't forget that IRender nXt also includes a robust set of post-processing tools that can be used to adjust color saturation, sharpness, and other image properties to enhance the rendered image.

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