Rendering Tip - Use Layers to Reduce Rendering Times

In this rendering tip I want to help you reduce rendering times for your SketchUp models by using layers to group light fixtures. When any of the lights in your model do not illuminate the scene you're rendering, turn the layers off and you'll be rewarded by a significant reduction in rendering time.

Use Layers to Reduce Rendering Times and Make Your Deadlines!

All of us have deadlines and our deadlines are unforgiving when an architectural rendering is expected for an in-house design review, client presentation, or Render Plus Rendering Tip essay. Meeting deadlines without compromising the quality of the image we're presenting means that it's important for us to discover ways to create high quality renderings in the most efficient way possible.

SketchUp makes it possible to build detailed models with relative ease and speed. Because skilled modelers work quickly, many ignore the layering feature available in SketchUp. Architectural models and in particular models that are to be rendered with a high-end rendering program can take days to render if the modeler doesn't consider how the rendering program will process the geometry, materials, reflections, and lighting to complete a presentation quality architectural rendering.

In this rendering tip I want to explore the influence of layers on rendering performance, strictly limited to processing artificial lighting. To focus on lighting the simple model that I built has only a few materials and no reflections. In this way it's easy to evaluate the performance improvements that come with using layers to manage lighting.

Three Buildings, 27 Rooms, 117 Ceiling Lights

3 Buildings, 27 rooms, 117 lights - Rendering Completed in 11 minutes 35 seconds

I'm always interested in finding ways to speed up processing time without compromising the quality of my completed renderings. As an experiment I made a quick model, three simple buildings each with 9 rooms. There are a total of 117 ceiling lights in this model. For the purposes of this tip, all of the renderings in this essay are 2000x1000 pixels, are completed in 50 passes, and an HDRi alone is used as the background and source of natural lighting. The rendering above was finished in 11 minutes, 35 seconds.

When I turn off the layers for 109 of the ceiling lights, leaving only 8 visible, the same scene with the same rendering options is completed in just 4 minutes, 16 seconds.

3 Buildings, 27 rooms, 8 lights - Rendering Completed in 4 minutes 16 seconds

Interiors - Use Layers to Reduce Rendering Times

For this model I added layers that group lights for each room in the model. For example, layer 2201 is the four ceiling lights in building 2, room 201, one of three rooms on the second floor of this building. The interior scene that I rendered is a perspective of room 2201 and includes a partial view of room 2202, through the doorway. I turned off all of the ceiling lights in the model except for rooms 2201 and 2202. The difference in processing time is quite impressive by comparison, render 117 ceiling lights (11 minutes, 22 seconds) or 8 (4 minutes, 58 seconds).

Interior Room 2201, 117 lights - Rendering Completed in 11 minutes, 22 seconds

Like you many of the renderings that I create are partial views of the models. These interiors are good examples. For these renderings in particular most of the artificial lights do not illuminate the scene, so my preference is to turn them off and not waste valuable computer time. The rendering above includes all of the geometry in the model and all 117 ceiling lights. The 2000x1000 pixel rendering, completed in 50 passes took 11 minutes, 22 seconds. The image is arguably no different than the one below which excludes the entire model except building two (reducing extraction time) and only the 8 ceiling lights that illuminate the scene. This rendering was completed in just 4 minutes 58 seconds, a considerable difference that gives me time to make a few more renderings before my deadline!

Interior Room 2201, 8 lights - Rendering Completed in 4 minutes 58 seconds

See also