Lighting Channels

Lighting Channels is an important new feature of IRender nXt which lets you quickly adjust light sources - sun, sky and/or artificial lighting - individually quickly to balance the brightness and light balance of your rendering.

• Now: Fully Integrated into the Batch Renderer

You can quickly adjust the intensity of each channel with a slide bar and immediately see the effect on the final rendering. This will saves time both in determining the relative intensities to use for light sources and in fine tuning the final image before publication.

While rendering, or after the rendering is completed, you can use the Lighting Channel Wizard to modify the rendered image by changing the intensities of the lighting channels. You can then adjust the intensity of the light sources, or save the Lighting Channel sttings to reuse the same channels in future renderings.

• Quickly adjust the final rendering to get the lighting effects desired.
• Adjust both the sun and sky to create dusk, or nighttime renderings.
• Add 'self glow' to objects - such as TV monitors, or illuminates signs, and adjust them the balance with the rest of the scene.
• Save time by not having to re-render after lighting intensity changes.

To learn more about Lighting Channels, see the Render Plus Videos and Tutorials|Videos and Tutorials.

Videos and Tutorials

• Lighting Channels Video
• Balanced Lighting Tutorial

Settings

Channels to use

For normal renderings, things will go faster if you use just one channel. (If individual lights are set to values larger than this number, they will be rendered in channel 0)

Default Channels

Default channels are set on the Light Setup tab.

The defaults are:

• Sun: 0
• Sky: 1
• Ceiling Lights: 2
• Other Lights: 3
• Self Glow materials 4

You can changes these default value and/or use the same channels for other lights.

For example, if you are not using Self Glow, you can leave it set to channel 4, but also use channel 4 for other lights.

Individual Lights

There are up to 8 channels available (0 to 7).

You can set specific channels for individual lights.

This can be done when creating the lamp, or as a right click edit once a lamp is placed.

Changing Lighting Channel Intensities

Lock Automatic Luminanceto keep other intensities the same while you adjust Lighting Channels

1. Click the Lighting Channel Icon at the top of the rendering window.( )
2. Name the channels if desired on the dialog.
3. Use the sliders to adjust the intensity of various lighting channels.

Normally, when you change the intensity of one Lighting Channel, all other illumination will change to compensate.

Automatic Luminance or Photometrics automatically adjusts the overall intensity of your rendering, much like the automatic exposure on a camera.

If you want to adjust Lighting Channels or other items without having Photometrics apply, you can lock the Average Luminance on the Tone Operator or Filters Wizard.

See: Automatic Luminance

Samples

Nighttime Scene

Image by by Christopher Alan Krupp on the IRender nXt forum. Lighting balanced with Lighting Channels.
Click to view full size.

Interior example

This is a model provided by Boothy for use in our documentation and tutorials

Here are 4 scenes from the model using lighting channels:

• The original rendering with default channel intensities
• An exterior, sun/sky only rendering
• An nighttime - no sun, dim sky - rendering
• A balanced rendering adjusting various channels.

For more examples of this model, see: Balanced Lighting Tutorial

Original Rendering - all channels set to the default intensity of 1.0	Nighttime - Sun and Sky turned off. For an evening scene, we would probably leave the sun off, but add just a little sky.
Daytime - no interior lights. Sky adjusted down, because at 1.0 it was too bright.	Balanced Lighting. Other - (lights outside door) and Self glow - (glowing panels on the wall) - made very intense (40.0) for effect and other lighting channels adjusted to achieve desired effect.

Guidelines

This powerful feature allows you to adjust many aspects of the lighting in your rendered image in real-time, after the rendering has been produced. This is accomplished by allowing you to create up to 8 lighting “channels” in the image. Each light source in the drawing, including the sun and sky, can be assigned to a channel. Once this image is rendered and saved, each channel can be individually scaled in the nXt Image Editor. For example, using this capability, you can produce day and night interiors with a single rendering. The following five steps are necessary to produce and manipulate a multi-channel image:

1. You must tell nXt how many channels you want. Go to Lights Setup Tab and set the number desired from 1 to 8, or check the "Use all Channels" checkbox.
   (Each additional channel you add requires an additional 12 bytes per pixel internally. This is a lot of memory, particularly for high resolution renderings. It may not be possible to complete your rendering on a 32 bit system.)
2. You must turn on all of the participating lights. Lights which are off will not contribute to the image and will not be scalable. Because you are rendering with more lights, it may take a little longer.
3. You must tell each light source which channel it belongs to. By default, Sun and Sky are set to channels 0 and 1, artificial lights to channels 2 and 3. You can changes these defaults on the Lights Setup Tab. You can also set channels individually for each light. Valid channels are 0-7.

Automatic Luminance

• As you adjust the channels, Automatic Luminance will compensate to keep the overall brightness of the scene constant. All of the tone mapping controls and rules still apply. For example, if you're trying to do a night and day exterior using the same rendering, you will almost certainly need to adjust the tone-op brightness down for the night time scene. Or Lock the Automatic Luminance while adjusting the lighting channels to keep the brightness the same.

See also

• Light Setup tab