Cineversity

Hello,

I got a project from a client which was created in R16 and R19, I have to adjust animations but it does render the highlights really weird. In R21 the highlights fdrom the HDRI totally burn out.

Has anybody got a clue what could be the problem here?

Hi visutainment,

Without any further information about the settings, it is hard to tell from the images. I can’t reproduce it here.

If you could just have that red object and HDRI in the original scene file. If you have no access to R16, you can upload the file to the link I have sent.

I will keep it private, and post only the same image as you did.

I don’t like to guess, but it looks like an AntiAlias problem, besides that, perhaps the HDR threshold in the Physical render needs to be lower. Again, guessing is not the ideal, as it puts more questions on top of the problem and perhaps is wasting your time.

I will have a look into the file ASAP.

Cheers, stay safe, stay healthy.

Thanks for the file, visutainment.

I can see the artifacts in the Interactive Render Region, and they get larger or smaller based on the quality settings (The little triangle on the right, up and down)

Rendering in the Picture Viewer, based on your settings, in R16, R19, R21, and S22, doesn’t give me any of these artifacts. Not in 8bit/channel or 16 bit/channel integer.

I can reproduce this when I go to 32bit/float. I checked the Sun in the HDRi, and it is way over 20 stops above. Even then, if I set the Anti Alias to Animation, it is gone as well.
https://help.maxon.net/us/index.html#DRENDERSETTINGS-RDATA_GROUP_ANTIALIASING
Any Anti Alias that has its function curve below zero at any time will create an artificial contrast (darken and brighten) that area, which is clearly present with such high dynamics.
Typically I would not recommend any of these sharpening fakes, as any color correction, later on, can’t pull the black values of these without harming the primary black levels of the image.
Besides, those areas are not super helpful to compress any longer animation.

I will switch to Animation AA for the rendering if you like to work in 32bit/channel float. Even the OpenEXR 16 bit/channel/float will suppress the 20stops+ values from the Sun center.

The next test was done with the given sRGB color profile as well as with a REC709 (since the settings were HD). I rendered it in PNG (as setup, and in 8 as well as 16 bit/channel/integer.) All fine.

I hope that helps.

My best wishes for your project, stay safe, stay healthy.

Thank you, that helps! Actually the client did only render 8bit pngs and I mostly use 16bit float EXRs when possible.
So I guess I have to stick to the original format. This scene is super broken in every possible way.

So would you say that the HDRI is not recommended to use, did I get that right? Beacause it is way overexposed or has to much superbright values?

Thanks for the reply, visutainment.

When I shoot an HDRi, I have to admit, I try to keep it below 20 Stops for the Sun, so the center has roughly a ratio of 1:1m to the rest of the image. The Sun is considered 400K times brighter than the full moon. It is quite challenging to estimate an exact value, as we always observe it through the atmosphere, hence the comparison. Any moisture in the air will lower its direct brightness.

It is not a secret that I don’t like the Radiance format (.hdr) a lot, as it is not a 32bit/channel format (it is a RGBE, or 4*8bit/integer). This means its values can be extremely high but posterized. Besides, its colors are not production-level quality. Is it usable to illuminate, sure, is the best one can use, nope. I store my work from the start in OpenEXR files. (Which is a container, and saving an Radiance into it will not improve it)

A good HDRI is doable with some care. But if it was not done with a gray-card, it is kind of useless anyway. What is the gray point, what color-temperature was baked into the material? (Note there is no real black-point and certainly no white point in HDR. … hence the gray card is the only fix-point) One could just paint an HDR map in Photoshop instead, and get similar results, perhaps even better results.

To answer your direct question, if you do not render the whole animation newly, you have to stick with it. However, since only 32bit/channel/float shows the artifacts, and any PNG 8 or 16bit/channel will not show it with your setup, use it. (I have tested only frame zero. I have not the capacity here to render your 3000 frames, in HD, or even with several releases.) If you color correct or not, sharpening should be applied as the last state, not during rendering, considering post-production.

As a side note, we are moving more and more into 4K and HDR as a delivery format. This might seems over the top for some, but if a Low-DR-HD clip is shown between two other clips in UHD-HDR, they will look dull and perhaps blurry on a UHD HDR screen in comparison. Maybe an argument to redo the whole project?

ENJOY.

Thank you for the detailed reply Dr Sassi!

I would love to redo the project but as I get only paid for some changes, the client will have to stick with this thing.

Thank you for your help

You’re very welcome, visutainment, thanks for the feedback.

Yes, the budget is undoubtedly a determining element in all of this.

Please let me know if there is any other “stopper” along the way, I’m happy to look into it.

All the best.