Size of the render boxes

[heavyweather]

I noticed that when I load the szene files from the book the small boxes that run over the monitor are only a quarter of the boxes in standart settings. Which setting does influence that behavior and what effect does it have on the rendering?

[dalomar_cg]

Re: Size of the render boxes

In the Systems rollout there are settings for the height and width of the bucket size in pixels. As far as what this does for the rendering process it basically decreases the portion of the scene that is rendered at a given time. This does decrease the amount of memory that is used, however, if you weren't running out of memory in the first place, then saving memory is a bit of a mute point. The downfall for decreasing the bucket size is that more time is spent determining what part of the scene each bucket needs and loading/unloading the information from that bucket. Also, depending on what method of calculation you are using and what the sampling rates are, you may either get what is called bucket artifacts which are artifacts that occur at the edge of a bucket where only a portion of the scene is used to calculate that area. If there are more buckets, that means more bucket edges and potentially more artifacts. In order to get around this, things can be set up to load those extra parts of the scene, but this will cause a given portion of the scene to be loaded/unloaded multiple times, thus decreasing the effectiveness of the smaller bucket size.

The long and short of it is that each scene has an "optimal" bucket size. Or in other words a certain size which balances the amount of time rendering/resources used for the bucket and the amount of time to process the loading/unloading of the bucket. Now finding this optimal bucket size may save at maximum 2%. 2% of a 3 minute render may be trivial, but 2% of a longer render may be worth it. Would I say that 16x16 (the size of the buckets in the vfr manual scenes) is the optimal bucket... probably not. If your really looking to squeeze every last drop out your rendertimes, then it maybe worth finding that optimal size. Personally I leave it at 36 or 48 or whatever the default bucket size is and worry about tweeking speed through the other settings.