Reality 2 noise reduction. Advice please.
Toobis
Posts: 964
For anyone who uses Realitiy 2 (latest version) with Daz studio....what are you best methods for reducing or removing noise altogether? and please don't be too complex when you explain. thx.
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Generally, reducing the reflectivity of surfaces (darker diffuse and specular colours) will cut down fireflies and image noise quicker. Other than that, time is the best answer I can think of. :roll: :coolsmile:
What's the scene and how are your lights set up?
Reality uses Luxrender, which has a completely different render method to 3Delight. As a result of this, light is calculated based on real world physics. As the above poster states, highly reflective surfaces will contribute to longer render times (thus, how long it takes to remove the noise) because the light beam is being constantly bounced around before being discarded. Check your surfaces glossiness and ensure that they're not too high.
The addition of multiple light sources can also contribute heavily to increased render times, as well as the formation of 'fireflies', little white specks which can sometimes never clear up. More lights means it has to calculate additional paths from each source, and the spots where they intersect can often be a haven for noise.
And finally... do NOT use skyboxes. Seriously. Avoid them like the plague if you're using Luxrender.
Because Luxrender uses real world calculations, the farther away an object is, the more time it takes for the light to reach it and come back. Your PC is calculating everything along the way for that 'photon' to reach its destination and back again. Skyboxes and Skydomes are generally large structures which are a long distance away from the actual scene, so your light beams have more work to do.
All renders generally clear up in time, but a well composed scene can render a lot faster than a messy one. More info on your scene can give us what we need to suggest improvements without compromising the scene.
The addition of multiple light sources can also contribute heavily to increased render times, as well as the formation of 'fireflies', little white specks which can sometimes never clear up. More lights means it has to calculate additional paths from each source, and the spots where they intersect can often be a haven for noise.
From what (little) I understand, though, the opposite can have negative effects as well. If my memory serves me right, using not enough lights can also lead to noise.
Also, glass. Damn you, glass!
Yes. I remember seeing a post from Paolo in which he explained that, just as your digital camera will produce 'noisy' pictures if there isn't enough light, LuxRender images will often feature lots of noise if they aren't sufficiently lit (although not for exactly the same reason).
If you get lots of noise that doesn't clear up, it may be that your scene is under-lit.
I use Luxus, but this is still relevant to me. I have found that, if I don't enclose my figures somehow that I get long render times and fireflies, especially when using area lights. Do you recommend that I continue my practice of building a box around my scene, just big enough to encompass the camera and lights? Or should I abandon this practice altogether?
You are free to continue slowing down your renders by enclosing everything in a bounding container if you like... :)
When a ray bounces out into infinity, Lux knows this right away, because the intersection test fails. Thus, it can immediately terminate the ray, regardless of how much energy or how many bounces it has left. When you enclose the scene in a box/sphere, the ray will never fail an intersection test. It will continue bouncing around inside the bounding container until it finally runs out of energy, or the maximum bounce count is reached. Those extra bounces take time to calculate, and slow down your render.
If you have actual fireflies (they are rare!), and not just noise that hasn't cleaned up yet, then you have seriously borked material settings. Things like setting glossy and/or specularity way off the charts, or using pure-white textures (NOTHING in the real world is pure white -- at most it's about 80% white). Or you are using hybrid bidir, which is broken. You need to fix the real problem, not enclose the scene in a bounding container.
LuxRender has long render times in general, so there is some expectation setting to be had. That said, there are many things that influence overall render performance, including geometry complexity, number and placement of light sources (and their relative gains), number of lightgroups, resolution you are rendering at, material settings like highly glossy/specular materials/mirrors/etc, volumes (glass, SSS), etc. In time, you will learn to tweak things to get the best results and performance out of Lux.
I use Luxus, but this is still relevant to me. I have found that, if I don't enclose my figures somehow that I get long render times and fireflies, especially when using area lights. Do you recommend that I continue my practice of building a box around my scene, just big enough to encompass the camera and lights? Or should I abandon this practice altogether?
Actually, in some instances using small enclosements is actually preferable, since you get the lovely bounced light coming from the walls without needing to add additional lights and such. Whenever I'm doing simple renders like single figures I generally enclose the area in a small cube. It provides both the background and the bounce without needing to concern myself with carefully positioning reflectors or similar.
Small enclosements like that can actually help your scene because the camera finds the light easier, thus making it quicker to render and helping, rather than hindering your scene. However, I would strongly advise against doing this for very large and complex scenes. In those instances, you're better off letting the rays fly into the void and be removed from the scene. If you need sky reflections, reflection maps are highly recommended in lieu of skydomes.
For both cwichura and HeraldofFire, I just posted a 9.5 hour render from this morning in this thread. Please take a look and tell me if thinking outside the box (pun intended) might improve the fireflies I still have after 9.5 hours rendering this. I have the Freak in a box, despite cwichura's advice. I will try again without the box, but not until my pc has a little break.