Cause of flicker in Vray animation and how to solve them

3 May, 2011 zero
3 May, 2011 # Re: Cause of flicker in Vray animation and how to solve them
Hi renderstuff it's good to know that you have this new feature here in your website. I would like to know what is the main reason why there is flickering in rendering an animation in vray and what is the best tip to have a smooth walkthrough animation.

3 May, 2011 RenderStuff (Staff Author)
3 May, 2011 # Re: Cause of flicker in Vray animation and how to solve them
Hi, zero.

We are glad to see you here in discussions 🙂

In order to understand flickering, we need to understand the principles of adaptability.

We have already described them in a tutorial about the creation of a virtual 360 degree panoramas. In particular, we have mentioned that the general principle of sampling results based on the principle of Buffon's Needle.

It is more specifically explained at the details of adaptability of adaptive GI engine Irradiance Map.

In short, when rendering, the engine takes only the most important color samples that make the biggest influence on the entire scene. They are taken from the scene geometry areas, which adaptive engine considers the most important. The remaining samples of the color in the missing areas, are artificially generated by interpolation from neighboring already calculated samples with each other.

In case of insufficient density of the samples, after interpolation, there may be artifacts in the form of dirty spots. This is particularly evident in small details. An example of such artifacts in the form of splotches and how to fight them, see in the article devoted to the choice of GI engines.

The main feature of adaptability is its random nature. That is, even rendering the absolutely identical frame with the same setups, you may get slightly differing images.

Of course, artifacts in these images will also have difference.

When we render the fly-through animations, where the camera just flies in the scene geometry, the each new frame will show generally the same geometry, but from different angles, different from those that was in the previous frame. Obviously, the artifacts of these frames will be different, because the adaptive engine that renders them, have other areas considered more important. This will inevitably lead to that the placing and form of artifacts will change from frame to frame 🙄

At the same time, we should keep in mind that the most prominent and chaotic artifacts occur in the GI. That is the GI artifacts appear in a scene the most.

Chaotic change in artifacts as the cause of rendering engine adaptability from frame to frame is the flickering. That is this change we see as a flashes in animation. That is to eliminate, or rather to keep artifacts similar, the fly-through animation rendering technique exists, in which artifacts are present in fact, but they remain unchanged from frame to frame. This makes the animation have no flickers 👌

The essence of the fighting with flickering is extremely simple. It just implies the use of large mutual for all frames GI map, previously created for entire scene, or rather for the parts that are seen from the complete camera fly-through.

Since that in fly-through animation all the scene objects are static and only the camera changes its position, then we can easily render one no-changing GI map. Of course, for each GI engine it must be their own. Then we need to render the entire animation using in advance calculated GI map for all the frames. This will not relieve animation from GI artifacts, but it will make them static, eliminating the GI flickering 😉

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