Cineversity

Can someone help me out with what’s going with my scene, please? I’m wanting to use an HDRI with a redshift area light. Its like the noise is happening everywhere but the shadows.I’m totally lost as to what’s causing and after watching some really good tutorials on redshift. If discard the HDRI and use the area light without it or as a shader the noise goes away. Thanks for your help

link to project file https://drive.google.com/file/d/16ApmCgEJUk1lB8jUgHtCVisVYAZ961gZ/view?usp=sharing

Hi hello,

This is a question for the Redshift 3D forum.

Thanks for your file, but there was no texture at all in it. Without all this individual data, any answer will be, to a certain degree, limited.
File> Save Project with Assets…

What you could do, replace the HDRi with a test texture, and see if the Noise is the same. See the image below. It will be very bright, so you have to adjust the result. This will exclude the or point to the HDRi you use or how you use it.

Please check the Redshift 3D forum
https://www.redshift3d.com/forums/viewforum/20/

My best wishes

Hi Dr Sassi,

Thank you for taking a look and apologize for not including the texture. Yea the exr you provided is noise-free in the scene as I found with other HDRi’s or just using native lights. I did have better results when changing the shape of the HDRi to something like a sphere. I will provide the file again with textures if you wish to take another look but I will head over to the redshift forum. Thanks for the help.

https://drive.google.com/file/d/1z9BQxtwo0gTuXI9sGfyDJ2Fzcd1jDqPh/view?usp=sharing

PS where can I change my forum name?

Hi hello,

Thanks for taking the time to reply.

To change your name, please use the contact us option (in the lower-left corner).

Any simulation of light is a reduced set up of reality. Always.

I’m not aware of any calculation of light that would work on any CPU/GPU available to CG artists. Light bounces around in a way that can’t be reproduced in any timely fashion.

So the idea is to find a way to get only relevant parts that calculate from the much smaller subset. Besides, most render engines see the light only as single frequency phenomena described as a ray.
Light bounces uncounted times, GI, on the other hand, tries to reduce the bounces to get affordable render-times. It is always a compromise.

This is by far not all there is to it, but in summary: it is not physically correct nor accurate. The keyword is, it comes close while having only a fraction of the calculation needed.

While 30 years ago, some techniques were the top-notch way to do, they are marked now outdated. Which will happen to anything, as everything progresses?

Please have a look here, scroll down, to see Pro/Con lists.

https://docs.redshift3d.com/display/RSDOCS/GI+Engines

Having said all of that, selecting what is used and (!) how it is used is critical.
Some methods work best with the artists’ support, some do better by just blurring (or reducing the size) the HDRI.

Fewer pixels mean that more rays hit the same (or similar) value more often, less noise. After all, everything in an HDRi becomes a light source, but what really needs to be in such details?

Baking parts or the whole scene, excluding small but hi-res objects, is a method used in Cinema 4D for a long. It depends if the scene has only camera animation in it or all is animated.

Thanks for the file, but it was again just a project file without any textures in it. I mention that, so you can create a file that is usable for the Redshift 3D Forum. Again File> Save Project with Assets… (Zip the main folder created based on this.)

All the best

lol omg sorry about file haha. Out of pure determination here is the zip file with what I hope includes the tex folder haha

https://drive.google.com/file/d/1pjQp1T1xRD-plnicaw3JF2MvqYe2QyzZ/view?usp=sharing

Thanks again for using a well-known cloud, hello, very much appreciated.

I checked the HDRi, which, from my personal view, has significant flaws. I do this to explore why it might be noisy. ( I do not explore the Redshift 3D set up here, as mentioned. So, let me be blunt, and sorry about that.

The first one being it is a Radiance image. Which is practically an 8bit/channel image (RGBE), blown up with a fourth (again only 8bit/channel: E) multiplier.
That format is really outdated and should not be used. There is not even any color-management possible.

Secondly, this image feels like a JPG Low Dynamic range, with a painted sun. Even when I go close with the color picker to the sun, it stays below 1.0 Way below.

I have no clue who produced it or what purpose it should have. You could use any 8bit/jpg and place a bright light for the sun on the sky, which would be many times better.

I checked the image in three applications (you can open it even in the Picture viewer and hold the cmd-key down, to see the values below the window).

All in all, excluding the sun, it has just six stops of data.(?) All the bright stones should be way over 1.0, or a polarizer was used, which would render the image useless from the start.

Sorry if I’m critical here; shooting HDRIs for a couple of decades made me picky. Here I liked to show why you might get the noise, as the sun is hit with a ray and then not. All-sky levels are a way to low to be true. So the jump from the sun to the close surroundings is already huge in a well-done image, here is extreme.

Perhaps check if you have not a better image. Find some that were calibrated with a gray card, anything else is useless.
Here is an analysis of the image from Photomatix.

If you want to shoot your own, see the link in my signature. The tutorials are based on decades of shooting experience, for my art or film-work.

Cheers

Hello Dr Sassi,

No need to apologize for being blunt…direct is the most efficient way:)

Yea I was starting to think it was something to do with the source file. Its from HDRi haven, a bunch of them I have from there do the same thing. I do however have some that work fine. I have to say that trying to solve this problem is out of sheer curiosity and I should really just move on so I can complete my project. In saying that I do appreciate your help and your answer has taught me things I find valuable. Thank you.

James

Just to add, Dr Sassi. I ran one of the hdri’s that seem to work through Photomatix and get an estimated dynamic range of 40:1. Is this considered good?

James

Hi James,
Thanks a lot for your reply.

What is good and what is bad is a difficult question, while having not seen the image. It has values double of what an integer can hold.

The best image in HDRI is the one that represents reality as much as possible, with the most steps.

So, if you take a light meter and measure the value of some points, that should be the same in the image.

If there is no sun in the image, then the range will be different from those that have the Sun not behind something.
The data that you showed seems like an image with a rich, detailed shadow amount, while anything bright is sitting between two stops.

I have more often than not, even without Sun directly visible, a problem to get a 360*180 in 12 stops captured. With Sun (note that it is a million times brighter than a candle), that is impossible.

If there is no gray card in use, the image says nothing: HDRI has NO black point nor a white point. These are limitations of tone-mapped/compressed images. Where white is given when all channels are clipped. Zero is not black; even the darkest black typically seen in this world reflects some light. So the only orientation is a gray-card 2/3 in the source, and 1/3 directed to the lens. From there, you can have something that is kind of OK. As long as the camera is not calibrated, it might not deliver correctly. Or the sequence of images is not sufficient.

Use the 32bit slider in photoshop to see how nicely an image fades out or whites out. The smoother and more prolonged the transition, the more data you have. Again, super dynamics are not the target; a resemblance with the reality is, to be comparable. Case in point, color temperature. What was measured? So, look at the image, use that slider, and see how smooth it is. Does it feel right?

ENJOY