I’m trying to find a way to light up a translucent glass material (using an area light set as a sphere object) without adding light to any of the other objects in the scene. I feel like I’m almost there, but I can’t prevent the light from affecting the floor. Can you please help me figure out what I’m doing wrong? Or, if you think there’s an easier/better way to illuminate a translucent material without affecting other objects, I’m all ears.
I’m prepared to attach my scene file and a sample render showing light spilling onto the floor, but the file size is 21 MB. If you’re willing, could you please open the bigger pipeline?
I have send you an upload link. If possible, only really the needed parts. No 3rd party stuff nor settings.
Anyway, since you prepped a scene already, just upload the file, I will look into it of course.
(Sorry, I have no power over any settings of the forum, I’m not an administrator)
The manual does not mentioned any limitations of the Light>Project include/exclude list options. Perhaps ask the support what they think is the correct behavior. https://www.maxon.net/en-us/support/how-can-we-help/
Thanks for your suggestion, Doc. I reached out to Maxon support for help. I haven’t heard back from them yet, but if they share any great ideas, I’ll be sure to let you know.
Doc, I heard back from Maxon and here’s what they had to say…
“After a few test renders on your project I can confirm that either using the Exclude field to exclude objects you don’t want illuminated, or the Include one to include only the ones you do want illuminated both work normally, at least on our end. There is some illumination being cast by the other light in the scene, however, which is causing the small amount of illumination in the scene. I also did a test render with the area light’s exclude/include fields empty and the scene was much more brightly lit which would indicate that it’s working as expected when using these settings.”
Doc, were you able to get the include/exclude fields to work on your end? I can’t get them to work on mine. The floor is always way too bright. I followed up with Maxon asking them to please share the revised project file or a render and some screen captures. If I receive any further enlightenment, I’ll let you know.
Given that, I think it explains what we both have seen in your file (to a certain degree, it has two key influences, see below).
But, yes, it delivers quite the impression as if the Exclude/Include isn’t working. (I even filed a report, silly me. The report is deleted, after trying it again with a new scene)
Please set the Floor’s Uber material>Diffuse>Intensity (try 10% instead of 100%)*
I have set both light source to just Include: both Glass material based objects.
*Perhaps set the area light to Sphere, instead of using the Object. The value of over 400% is certainly a reason for the “super values”. Just a thought. Perhaps better to lower the value than to dial the Intensity so strongly down.
Doc, thanks for all of your help with this! Although I’m still not getting the complete look that I’m after, it is indeed an improvement…and every step forward is appreciated.
Just a few thoughts, so we are on the same page, or at least understand what idea we have about those “globes”.
Normally I understood the floor as a shadow and caustic catcher. Perhaps to a certain degree as well as an Ambient Occlusion and light/color spill indicator, hence the gray value. What is really the look you want from the floor? Independent from anything or part of the scene.
Those globes work well, if the set up is always in the very same way, so one can read the differences quickly. Which means an set up with, e.g., 50% (0.18) gray should just be an over all average and work well. I use that mid gray idea, as in the physical world, we do not have a white point (it is certainly not 100% of an 8bit/channel images, there is is just the clipping point, so an limitation), and a black point is also somewhat blurry as well.
In HDR I use a gray card as the only source to evaluate (besides a macBeth chart, for more precision). But as we all know, the white and black-point on an exposure bracket doesn’t really care about black and white points, at least not in my shooting experience over the past 15 years taking HDR images.
Which brings me back to the Globe and the idea of a well exposed mid gray globe, that should be the reference. If you set this up, you get the information needed, what a new material really does. I assume a light of over 400% might not follow this idea, nor adjusting the floor for that matter.
Doc, what I am ultimately trying to do is match the look of a Redshift material that I created last year. I’ve attached the material so you can see it. I don’t know the coding/physics/math behind the Redshift renderer, but one thing I do know is that Redshift makes it much easier to work with materials. With a lot less effort, they just seem to work…especially translucent materials. This particular material was lit the same way I lit all of my Redshift materials…using only an HDRI which fills the materials with light in a glorious way. I’m not sure what direction Cinema 4D is moving with ProRender, but I look forward to the day when materials are as easy to work with as in Redshift. In the meantime, I’m going to enjoy working with Cinema’s best features, such as MoGraph, Volumes, and Fields. So much to learn!
Mark, I do not have Redshift (I don’t have the needed compatible hardware to begin with, but maybe a new computer and the Black Magic Graphic card will do the trick, but it needs time to get there, since I stay with Apple). So, I can’t really explore this.
I’m not as far with the new Node system as I would like to (I had some intense but fun training sessions to do and currently prepare a presentation for NAB NYC), but I hope that I will feel soon as comfortable with the node system as I do with Xpresso, for example. At least that is the target here. I will keep your glass idea in mind and will share any findings I can get.
As of now, Redshift only works with Nvidia graphics cards. I bought a PC system with 4 1080 TI cards and am simply blown away by how fast I get creative feedback (and by how fast it renders). I has completely transformed my creative life.
I’m gradually learning the new node system, but it will take a looooong time to understand many parts of it. As I learn, I’m building a node-based material pack that will eventually be for sale on The Pixel Lab site.
Best of luck with your presentation at NAB. Have fun, Doc! If you discover any enlightening glass illumination secrets, please share them.
Yes, Mark, the Node Material System has a lot of functions which were previously only available for coders of rendering engines. This new option in R20 is like a plug and play version of code. It can be as simple as to just adding a few nodes, but also to evaluate the scene with many of its parts for effects. I guess we all will see a lot of options with it in the near future.
The feedback time of anything is absolutely a key to learn, evaluate and then adjust accordingly in a scene. Certainly a huge creativity support, I agree. Compared to where we are now, to a quarter century ago (my starting point), it is just great today – and it gets better every day.
