Join Brian Bradley for an in-depth discussion in this video Fixing super bright sampling problems, part of V-Ray 3.0 for 3ds Max Essential Training.
- Every now and again as render artists we come across a scene that almost feels designed to cause a plethora of problem sorrows. One such instance is when we find a scene that has been composed and lit in such a way as to make it very difficult indeed to get a clean, reasonably fast render from it, such as the example we have here. Lots of glossy and blurry reflections, a very shallow camera angle, and a cranked up HDRI inside a V-Ray dome light are all combining to produce the bitty or noisy looking render that we see here.
Now we could of course bump up image sampling in the scene in an effort to clean things up. The problem with doing that would be that our current render time of just under three minutes a frame would increase by quite a significant amount no matter which sampling engine we decided to use. A better first port of call here, given the problems that we are seeing, would be to try and make use of V-Ray 3s new Max Ray Intensity parameter found in the global switches rollout with Advanced UI mode enabled. This ray clamping option gets applied to all secondary rays in a scene such as GI, blurred reflections and refractions and so on, as opposed that is to clamping the image's actual pixel values.
Now although the troublesome flow pixels that we see here aren't necessarily super bright in and of themselves, the image sampler is having problems with them because of the super bright reflections on the cars that the secondary rays are having to sample. If we enable the Max ray intensity option then, save the render that we have to the history list and then hit the Render button, we can take a look at what this option can actually do for us. What we instantly see is a massive improvement in the way our ground material at least is rendering, and this using just the default max ray clamp value of 20.
Now whilst our car reflections have been altered a little by that change, becoming a little less noisy, we do need to keep in mind that, because the majority of what we see in the reflections is created by the primary reflection rays, the max rays intensity option isn't going to affect our reflections directly. Remember this parameter works on secondary rays only. Of course if we're happy with what we have managed to accomplish up to this point, we can simply move onto setting up our final render options.
What though if we wanted to take a bit of the zing or edge off the reflections that we're seeing. In that case we may want to jump into the Color mapping rollout and make use of the Sub pixel mapping and Clamp output options that we find there. Now whilst neither of these individually will make a difference to what we're seeing in the reflections, if we enable both of them together, save the render that we have to the history list and take another render, we can see that we do indeed clean up our reflections quite a bit.
One thing we do need to keep in mind however is the fact that we have now clamped our entire image, effectively stuffing its entire contrast range into the zero to one space. We can of course control the range that we've clamped to by means of the numeric field that accompanies the Clamp checkbox. Indeed if I set this at a value of three, save to history, and then rerender, you can see, as I compare to our previous image, that we are now able to bring back a little of that zing in the reflections.
Again though the image's contrast range is still clamped inside a limited, if somewhat larger, dynamic range now fitting into a zero to three space. Let's assume though that our art director or client is wanting to be really picky about the way things are looking here and decides that whilst the car reflections are perfect, the floor is actually now a little too dull and needs to the reflections to be brighter adding some of that earlier noise back to the image if you like. Well, we can easily do that, no problem, by going back to the Max ray intensity value, raising that up to something around about the 100 mark and then after saving to the history list, render one last time.
What we get now has clearly come a long, long way when compared to the render that we originally started with. And of course in achieving this cleanup we should keep in mind that we have increased neither the sampling levels in the scene nor amazingly our render times.
- Using the new UI elements, Quick Settings, and revamped Frame Buffer
- Understanding color mapping modes
- Adding V-Ray light types
- Working with the V-Ray Sun and Sky systems and dome light
- Using irradiance mapping and light cache
- Working with diffuse color maps
- Making reflective materials
- Creating a translucency effect
- Using the new SSS and skin shaders
- Ensuring quality with image sampling
- Working with the adaptive subdivision engine
- Controlling the physical camera
- Working with FX tools such as VRayFur and VRayMetaball
- Stereoscopic 3D rendering
- Using Render Mask
Skill Level Intermediate
Q: This course was updated on 02/02/2016. What changed?
A: We added tutorials on the new 3ds Max camera tool, which replaces the defunct V-Ray Physical Camera. The author also includes a method for creating a V-Ray camera via scripting.
Q: This course was updated on 04/19/2018. What changed?
A: New videos were added that cover V-Ray 3.1 to 3.3 updates.
SketchUp: Rendering with V-Ray 3with Brian Bradley4h 15m Intermediate
V-Ray: Control Color Bleed in SketchUpwith Brian Bradley1h 2m Intermediate
Introduction and Important Information
V-Ray 3.1 to 3.3 Updates
V-Ray 3.4 to 3.6 Updates
1. Getting Ready to Render with V-Ray
2. Key Lighting Tools
3. Global Illumination
4. V-Ray Materials and Maps
5. Quality Control with Image Sampling
6. Working with Cameras: The V-Ray Physical Camera
7. Working with Cameras: V-Ray 3 & the 3ds Max Physical Camera
8. The V-Ray FX Tools
What's next?1m 47s
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