Chaos Corona for 3ds Max > [Max] General Discussion

Stupid questions


(not sure if this belongs here or to "tutorials and guides")

I'd like to ask some questions that would clarify my vision of how Corona works. I think they might be obvious for those who have more theoretic knowledge about rendering systems, but I'd really like to know this. Maybe other forum users have similar questions so this thread might serve us as noob centre. And yeah, Keymaster, I promise some day I will read whole your Bachelor and Master Thesis. :]

1. When I use HD Cache only, rendered image comes out as a mix of random paint-like splotches all over the scene. I bet that's how it works, pretty much like Light Cache in vray, right? Averaged samples from a certain radius?


What happens when I use Path Tracing + HD Cache? Does it use data collected from HD Cache to speed up path tracing? What's that green-coloured stuff shown in precalculations? Areas that are considered too important and will only use path tracing?

I'd also like to know how certain "thresholds" work. To make the GI calculations more precise and slower, should I lower some parameter, or make it higher. For example:

-Interpolation sensitivity (dir/pos/norm) - I bet making them HIGHER than default values will make HD Cache calculations more precise OR will force it to use Path Tracing in more areas (?).

-Glossy threshold - lowering it will make reflections use less HD Cache and more PT thus making them more precise?


Oh, and one "bug" about the Corona Render Settings website ( ). It's neat, but when I scroll down and want to read about some values that are listed at the bottom of the page, the popup frame doesn't fit on screen and I can't see lower part of it. Maybe it's a matter of my browser (Firefox) or screen resolution (1680x1050)?

1. you're right, its averaged nearby discrete point samples.

If you use PT+HD, then the camera rays hit the scene, split into multiple secondary rays, that go from the primary hit point in random directions, and read the value from the HD cache where they hit the scene. Its basically final gathering, but with HD cache instead of photons

green stuff in precalc is "Let's rather do more path tracing here instead of using HD cache"

increasing interpolation sensitivity makes the records denser (due to glossiness, geometric details, or normals, respectively). It also increases the size of the areas where HD cache is not used at all, because it wouldnt be effective (basically the records would be so dense, that there would be one record for each interpolation - in that case it makes more sense to do the basic path tracing instead)

glossy threshold is basically increasing the green areas on glossy surfaces. You cannot use the cache for example on mirrors (because you would see the splotchy thing - you need the rays to spread out to blur out the splotches in cache), You also probably dont want to use it on almost-mirrors. This number tells you how much is the surface allowed to be glossy to still use HD cache for it.

Oh, and I've "fixed" the "bug" with displaying the documentation



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