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10 top rendering tips

Top 10 rendering tips! Learn to render better, smarter and more effectively. Our panel of experts reveal their top tips and techniques for successful renders

Top 10 rendering tips! Learn to render better, smarter and more effectively. Our panel of experts reveal their top tips and techniques for successful renders

Rendering might be less fun and less exciting than the other parts of the 3D process, but its just as vital. Its such a time-consuming process that if you dont know what youre doing, all youre doing is wasting time. Of course, done right, that rendering time is a good opportunity for you to process too, and when you get your finished renders out, hopefully you can come back to the work with a fresh eye. But first, you need to get those passes the way you want them, as our experts explore.

Rendering a normal pass can be really helpful to add extra light to a rendered image. Each channel can be used as a light source, coming from each one of the 3D world axes Carlos Ortega Elizalde

Render separately

Sometimes my renders need a little sprucing up. I render out elements (background, foreground, character etc) as TGAs with alpha channels, then comp them in Photoshop. Adjustment layers such as selective color, hue/saturation and levels help me control the tones of the image. I also use vignette and iris blur if needed. I stay away from the chromatic aberration slider though I see it overused far too much these days! Andrew Hickinbottom

Comping together work in Photoshop gives you the chance to look at it fresh

Comping together work in Photoshop gives you the chance to look at it fresh

Normal passes

Rendering a normal pass can be really helpful to add extra light to a rendered image. Each channel can be used as a light source, coming from each one of the 3D world axes. While it does not represent physically accurate light, it helps artistically to accentuate important or lost zones of a rendered image by simulating a rim or a bounce light. It saves a lot of time to avoid re-rendering by tweaking or adding lights, and it works too in composition software for animated sequences. Carlos Ortega Elizalde

Time-saving tips are exactly whats needed

Time-saving tips are exactly whats needed

From the modeling to the texturing to the lighting, every little detail will add to the splendor of your final render © Carlos Ortega Elizalde

Create a spec pass...

To create a spec pass in Keyshot I usually use a wax material with 0 translucency and maximum specularity, then I turn the SColor and the Subsurface Color to black. Next thing to do is to make the background black and then I use the HDRI Urban to light the scene. Luca Nemolato

Keyshot passes can be just the way to tweak your image to perfection

...and a skin pass

To obtain a good and fast skin pass in Keyshot, I usually use the Human Skin material with the translucency set to 0.7 (this can vary depending on the model), roughness to 0.8 and then I load a Texture map and a Normal map. Usually I light it with the HDRI Factory." Luca Nemolato

Skin is something worth taking extra time on. So just experiment until it looks right!

Render only what you need

When working on 3D illustrations for print, often the render resolution needs to be quite high and I often create final renders at 6k or 8k. This requires high-resolution textures, which will slow down rendering and Mayas Hypershade. As these textures are only required for final renders, I will duplicate the directory with my textures and resize them down by up to 90% for test renders. When tweaking materials and lighting, I dont need über high-res textures slowing down the iterative process. Alex Alvarez

This scene had several gigs of textures. Resizing textures cut test render time by 75% while Alvarez was designing the scenes lighting

Test it first

Render a few tests in low resolution format before advancing into the final render and make sure that all the settings are optimized to get a very good result without illumination errors or undesired glitches or spots on the image. For example, I render in a low res such as 800 x 800 up to 1800 x 1800, and for the final render I always set a resolution of 5000 x 5000 with all the important passes that I use for the post-production phase. I save this in the format HDR because I want to have all the exposure control to adjust it. Sérgio Merêces

Quick tests can save you hours of waiting

Color correcting

RAW renders sometimes dont look as good as one would expect but having an option to use Photoshop, Fusion or NUKE to push these renders though post-processing is a great way to increase the visual quality of images. By doing masked color corrections, defocusing some parts, adding noise or sharpening specific parts of the image, important areas of the renders can be manipulated to attract more focus, while less important parts of the image can be pushed to darker tones. Toni Bratincevic

Making things darker or lighter or brighter or otherwise dramatically different is still within your grasp

If youre unhappy with your render, then go back to your initial idea. As Toni Bratincevic says If it does work as a layout, there is already a good established composition and simple models, then after this point it is just a matter of technical skills to model/texture and light everything. © Toni Bratincevic

Plan to pass

Plan on rendering out different passes for anything that is either reflective, incandescent or translucent; this will allow you to reshape these passes in compositing using rotos and gradients. Rendering out elements such as foreground, midground and background to their own respective layers will also allow you more control in compositing. And remember, hide everything that doesn't appear or contribute to the render. Turn off shadows and contribution to the GI and reflections for anything too small to be noticed. Matte paint anything that is far enough from the camera to have no parallax shift. Francesco Giroldini

Different passes allow the different strengths of your work to shine through

ID your image

ID mattes are one of the cheapest and most powerful ways to alter a picture after the fact. Assign a flat bright red green or blue shader to elements of the scene, render them from the same camera as the beauty image and key them out in compositing to create custom mattes to be used to color correct the image in compositing. Francesco Giroldini

Its never too late to fix something

Dont render what you dont need, says Francesco Giroldini © Francesco Giroldini

Pull the look together

What you get out of your render engine generally only takes you about 90% to final. The last 10% is accomplished in post and can make the difference between something looking CG or professional. Spend time learning the limitations of 3D render engines in regards to making images look like they were shot by a real camera. These elements (glows, blooms, glints, grain, contrast) are easily added in post, not to mention harmonizing color and defining the style. Tools such as Magic Bullet Looks are easy to use and are generally real-time, making the process far faster than trying to simulate them with your render engine. Alex Alvarez

Explore different looks to an image with Photoshop and Magic Bullet

This is the straight render from mental ray that Alex Alvarez produced for his image 'Meadow' © Alex Alvarez

Here are the textures Alex Alvarez cut from his Dirge render tests © Alex Alvarez

Render, and then rest

Hopefully, if youve done your job properly, youre happy with your renders and even happier with the finished product. And if youre not, then theres always the next project to think about. Next time, your modeling will be even defter, your texturing subtle and sublime, your lighting sparkling and your renders a reproduction of perfection. Next time, itll be just like the image in your mind. And if not? Well, you can keep trying and trying again.

Plan on rendering out different passes for anything that is either reflective, incandescent or translucent, this will allow you to reshape these passes in compositing using rotos and gradients Francesco Giroldini

Related links check out the sites of our top tip artists:
Francesco Giroldini
Carlos Ortega Elizalde
Andrew Hickinbottom
Luca Nemolato
José Alves da Silva
Sérgio Merêces
Toni Bratincevic
Pascal Blanché

For even more tips, try these:
10 top lighting tips
10 top 3D texturing tips
10 top 3D modeling tips

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