Before you start, consider what type of rendering you want to achieve – photorealistic, or artistic? There’s no right or wrong way to do a rendering, and it all depends on your intentions and what you want to convey when presenting the rendering of the space to your prospective customer. The answer to this initial question will affect how you should go about renders.

Image source: Some images in this article are from REDsdk’s documentation.

1. Use area lights for ceiling lights

To provide soft, evenly spread illumination for the space, check the Use Area Lights option in the property box when using the Ceiling Lights in the Lights Extension:

Original image to the left, image with the Use Area Lights option activated to the right

2. Avoid using omni lights unless necessary

All light sources should have a visible source that the viewer can determine where the light is coming from. Omni lights can result in unnatural looking renderings which depict an invisible light source casting shadows all around. Over-using omni lights can result in slower renderings as well. When you do use omni lights, make sure they are not too bright so that it is not obvious the light does not have a clear source.

3. Experiment With Light Settings

Use the Light Settings in the quick properties box of a light to adjust the brightness, and other light settings such as Shadow Softness, Temperature, or Direction to achieve different results. Organize the sources into Light Groups to change the settings all at once. However, note that different kinds of lights have different behavior with regards to the settings. Some lights do not light up as much with a +10 brightness compared to other lights, so be mindful when combining multiple light sources. 

4. Preview Results Before Render to Avoid Over- or Underexposure

Use the Preview feature in Photo Lab to preview the lighting of the space before rendering. Avoid overexposure by removing unnecessary light sources or toning down the brightness settings, and avoid underexposure by first trying to increase the brightness of existing lights before adding additional light sources.

5. Use Natural Light Presets such as Product Lighting or Realistic

These presets provide a good starting point for background lighting and have the best settings for photorealistic light and shadows.

About Light Presets

Light presets in CET influences the way lighting and shadow effects are rendered in CET, and provide a template for sunlight and ambient lighting. Two main types are Normal presets (Realtime, Multiple Suns, Normal, Office Lighting, etc.) and Natural light presets which are of higher quality and provide a greater degree of photorealism, with enhanced subtle details like color bleeding, indirect light reflections, and shadows. Some of them are:

• Product Lighting: Uses a soft, even, ambient lighting for renderings. However, sunlight or camera is not available. This preset works best with standalone product shots, or open space designs that let ambient lighting fill the space.
• Realistic: This preset works best with fully enclosed spaces. 
  • Sun: Uses a sun dial to change lighting direction and shadows. 
  • Background: Uses the HDR Background to determine lighting and temperature.

Please note that light presets do not automatically add lights in indoor scenes where sunlight and ambient lighting is unable to reach. For indoor scenes, it remains the responsibility of the designer to create a proper lighting setup to ensure that it is well lit.

6. Use High Quality Settings

This increases the quality of the model used in renderings, and is especially important if you have lots of glass or reflective materials. High Quality setting ensures that shadows through multiple layers of glass, reflections and refractions are properly rendered.