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Tue, Jul 26 2011 20:18:33 UTC

Tips for making more realistic 3D renders

Getting realistic renders is what many 3D modelers are aiming for, especially when working with photos or video, where the resulting renders have to be composited together. One popular saying is that good visual effects are those you don't notice, the ones who blend in perfectly with everything else, and that requires good, high quality renders, something that takes some time and learning. In this article, we'll see a couple of things you can do to get more realistic renders.



Choosing the right renderer


The first tip is to use the right renderer. For some, this may seem self explanatory, but many people underestimate the huge difference changing renderer makes. 3DS MAX's default rendering engine, for example, is Scanline. But nobody would use it in production. In fact, there's a couple of renderers that are used in most production studios. But again, it depends on what kind of renders you're doing.

There are two types of renderers: biased and unbiased ones. With an unbiased renderer, such as Maxwell, Octane and LuxRender, the radiance approximation has no bias in it, so the lighting values are correct. However, this requires a very long render time, and if the renderer does not take the necessary time, high-frequency noise will be introduced.

A biased renderer such as V-Ray and MentalRay will use various biases in the final render. This does not necessarily mean the resulting image will look worse, in fact it may look better, it just may not be mathematically correct. Also, the render will typically be much faster.

Going beyond this however, another important thing to check is how much control over the render you have and what features the renderer offers. For example if the render engine you pick provides true raytracing it'll likely be better than one who does rasterization.



Choosing a renderer is no easy task, and typically to get a good result, you'll need to spend a lot of time making test renders, playing with the options, and that's why if the renderer has a lot of control, and is intuitive, that can go a long way in allowing you to get more realistic renders.

Getting proper lighting


Lighting is the second most important thing to look at after you pick your renderer. Typically, you should try to mimic real lighting situations if you want photo-real results. That means if there's a light fixture with 3 bulbs, you should probably put in 3 point lights. That isn't to say cheats should never be used. The final result is what you look at, so if it looks better with an extra light then you can do that.

Past the positioning of lights, two very important features are shadows, or soft-shadows to be more precise, and volumetric lighting. Soft-shadows allow the shadows to have soft edges instead of hard edges, which is what happens in real life. As light travel through air, the shadow it casts will rarely have a sharp edge, especially if the light is far away. Volumetrics is when light rays can be seen, and can add a lot to your scenes.



Shaders and textures


Textures start with a simple color, and then an image map that is applied to a surface. But there's so much more to it than that. If you look at the textures dialog of any professional modeler, there's a lot of features and options there. To get a realistic effect, the proper values should be used for bump maps, displacement maps, reflection, specularity, and so on.

Typically, more hobbyist programs or products will take shortcuts, like using the same texture image for the texture and the bump map, use a reflection map instead of proper raytracing, and so on. While it may not be noticeable in the final image or animation, that's just not how the real world works, and these values should be adjusted.



Post-processing


The final tip is about post-processing. Regardless how good you manage to get your render, chances are it still won't be believable as a photo-real image. To sell the effect, post-processing can go a long way.

Typically, photos or videos are not perfect, regardless of the cameras used. There's motion blur, unfocused elements, lights reflecting in the lenses, and so on. By replicating these effects in post, using Photoshop or another 2D software for images, or in a 3D compositing program like After Effects or Final Cut, you can apply many different filters and adjustments to sell the final effect.



Remember that photo-real renders is not always the result to shoot for. It is in many ways the hardest result to get, because if you come very close but not exactly, you'll get what's called the uncanny valley and it'll look worse. But if you apply the tips above and practice, then you'll be able to do professional effects that look right out of a Hollywood blockbuster.

Do you have any other tip to improve photo-real renders? Let us know in the comments below.

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© 2007-2019 Patrick Lambert - All resources on this site are provided under the MIT License - You can contact me at: contact@dendory.net