Tips for More Efficient Rendering

Dan Chartrand is a Landscape Architectural Technologist at Associated Engineering in Edmonton, Alberta, Canada.  In Part 1 of our interview with Dan we touched on his use of SketchUp and our IRender nXt rendering extension.  Dan described some of the features he uses to produce renderings that impress and inspire AE’s clients, helping to maintain their standing as one of the best consulting engineering companies in Canada. 

While Dan is a big fan of IRender nXt, he highlighted several areas of the program which he finds challenging.  Dan's challenges are similar to questions we’ve received from other users, so we decided to provide insight and tips to help you all hone your rendering skills.  For further clarification on the following information, or if you have other rendering related questions, please email Render Plus Support Email or use our Forum.

Rendering Time

Question: The rendering process, though it looks amazing in the end, tends to have a huge variance in the time it takes to render an image. I have had an image render for 6 hours, or as little as one hour. This can be a gamble when working on a time sensitive project where the client is requesting some changes within the model, resulting in re-rendering and a loss of time or quality.

Answer: There are lots of factors that can impact rendering speed.  If upgrading your computer to the fastest processor with the most cores/threads available is not an option, here are links to two pages on our site that include lots of tips for decreasing rendering time:  Tips for Faster Rendering 1 and Tips for Faster Rendering 2.  Here’s a handful of the most common ways in which to reduce rendering time:

• Only model what you need in your scene: Items which are not visible slow down the rendering process. You can organize different parts of your model by layer, or just simply hide items which are not needed.
• Be efficient with your lighting:  The fewer lights you have in a scene the quicker it will render (the more lights the scene has, the more calculations the software has to run).
• Set reflective materials properly:  Reflective objects that don't have anything specific to reflect will just slow down your rendering, processing reflection which doesn't really affect the final image.
• Remove complex components: Try and reduce the complexity of your model by removing, or simplifying, complex components.  Try rendering components you import in a bare / new model before including in your actual model to test whether they render efficiently.
• Replace high geometry items with texture images: Geometry in the background that has lots of faces can often be replaced with an image placed as a texture on a face. 

HDRi Sky Blurriness

Question: I have still not been able to figure out how to use the HDRI Sky + Background option. It keeps coming out blurry. I have resorted to rendering out images as a transparent PNG, then adding in my own background in Photoshop. This is useful, but sometimes IRender still includes a background and when working with trees in the background, selecting the background between the leaves in Photoshop becomes tricky and frustrating.

Answer: The blurriness is likely because you are using a low resolution HDRi.  We provide some high resolution HDRi’s via IRender, and there are many sources of HDRi’s on the internet including HDRI Haven who we feature in our monthly newsletter.  To render without a HDRi background make sure you choose the Preset “Exterior with Sun”, not “HDRi + Background”.

Animation Rendering Time

Question: At one point, I attempted to make an animation using IRender, but it was going to take over 60 hours for one transition (about 7 seconds), so I had to scrap the idea, because there were about 13 different transitions within the model.

Answer: Animations can take a long time to produce as each frame is rendererd individually and each second of an animation includes multiple rendered frames (images).  There are several ways in which to reduce the time it takes to produce an animation including defining the minimum number of frames you need per second to produce an acceptable movie motion, and rendering at a lower quality than you typically render a still image (the human eye doesn’t discern a high level of quality viewing a movie so frames can be lower quality = less time rendering).  We recommend that you experiment with these variables before rendering your whole animation – it can save hours.  We also have a new “Key Frames” feature that allows you to render the frame a user sees during a scene transition to a higher quality (as the human eye will recognize the quality of this momentarily stationary image).

Thanks, Dan!  We appreciate you highlighting these areas.  There are obviously many variables that can impact rendering and we're glad you asked about these different areas we could help you with your setup.

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