Neutral Balance Grade: How to Perfectly Integrate Film & CG Renders for VFX Compositing
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- čas přidán 25. 06. 2024
- Walkthrough of the process in VFX for doing a reverse-out neutral grade by calibrating the image to match the color gamut and white balance of the target color space (ACEScg) using a Macbeth color chart, and likewise calibrate the HDR captured on set to the same target color space, using this to light the CG assets with neutralized image-based lighting.
DOWNLOADS
HDR assets from the Katana Lighting and Rendering Master Class:
learn.foundry.com/path/11/kat...
Marco Meyer's Color Target Gizmo (including NumPy)
sharktacos.github.io/VFX-soft...
CHAPTERS
0:00 Understanding Color Balance
2:08 Reverse-Out Color Balance with Grade Node
4:30 Neutralizing Film Plate with a Color Checker
8:56 Neutralizing HDR for image-based lighting
17:19 Workflow Review
This is gold! Such a great workflow. Amazing tips and tricks. Well done
Thanks a ton!
These ideas are awesome! Even though there aren't many views, you're really helping a lot of people. Please keep up with this channel!
Thanks, appreciate it!
Awesome channel, keep it up sir 😁👍🏻
Thanks!
brilliant ! Thank you for doing this.
cheers,
b
My pleasure!
great video
Thanks!
thanks for sharing
You're welcome!
hi! thanks for sharing, if you don't mind I've got a question.
If i have a plate that's in aces2065-1 colorspace and a HDRI that's in srgb colorspace that's meant to be brought in to 3D. do you reckon that I should neutralize the plate with mmcolorTarget set to aces2065-1 colorspace and HDRI neutralized with srgb colorspace, before bringing the HDRI to render the CG elements for comp with the neutralized plate?
Assuming that you are working in ACES in both Nuke and CG, you would want to bring everything into the working space of ACEScg. For an HDR that is in sRGB linear, you would set the input transform to that which means it’s converting it from sRGB linear into ACEScg. Similarly for your footage you would set the input transform to ACES2065-1 which means it’s converting it from that into the working color space of ACEScg. Then you can calibrate everything as shown in the video.
ooh yea thanks for the quick reply! me and my colleague were testing it out today and it seems that we're pretty much on track as our steps were exactly like what you explained haha! Nice to get confirmation on this! thanks again man! @@derekfloodVFX
Thanks! Why is a copy of the Macbeth table created in 3d and what does it affect? Everything seems to have become clear about the spheres
It’s standard practice for lookdev. The Macbeth colorChecker in the CG serves the same purpose as it does in the plate photography, which is a ground truth for the color. CaveAcademy has a nice article on this. caveacademy.com/wiki/onset-production/data-acquisition/data-acquisition-training/the-grey-the-chrome-and-the-macbeth-chart/
@@derekfloodVFX thanks!
Does the window reflection for the cg object come from the isolated area light? What would you recommend, if the cg object is moving in the shot, dome hdri?
It would still come from the area light if the CG character is moving. The principle is having HDR objects in their correct location. A dome light is less accurate because everything is infinitly distant.
another question would be:
if i wanted to add a cg scene in to my plate which is shot with multiple colored lights, (eg, razer chair photography with colored lights)
how would the workflow be like? I imagined that I should just match the HDRI colorchecker colors to the plate footage using the mmColorTarget plugin but my HDRI doesn't have the same colorspace as my plate, I'm not sure if there's any steps that I'm missing here. Do I just bring in my HDRI (srgb) and read it as Utility-Linear-sRGB in nuke before using the mmColorPlugin to match the colors?
hope to hear back soon! Thank you so much!
Yes. See my previous reply 😊
Hello! Why u neutralize plate with aces-2065 to aces-сg a not for aces-2065?
ACEScg is the working color space for Nuke. So all images are brought into the working color space, and therefore that is also the target color space to calibrate to.
project has HDB0010.2k.ref.ntrl footage and HDB0010.2k.ref.1001 footage.What difference use ref.ntrl and footage? if i convert both footage to aces cg i still get same color and gamma image?
The ntrl footage is neutralized, as explained in the video. Both are already in the ACEScg color space. Color space and neutralization are not the same.
@@derekfloodVFX I try neutralise original footage with mmcolortarget but I have different exposure with ref.ntrl. Or I will get same footage?
@@cinemacult1346 sorry I'm not understanding your question.
what differnce between CalibrateMacbeth and mm_color target tool?
Different tools for similar purposes, one made by Marco Myer and the other by Jed Smith. You can read about the differences on their respective websites.
Hello! i create hdri with ricoh thetha z1, how to convert hdri to aces?
in the Read node in Nuke you can set it to whatever color space it is in (most likely Linear Rec.709/sRGB) and this will convert it from that color space into the working color space (ACEScg).
Cool!Can u tell how to setup numphy on python 3.8+ version???
If you have Houdini installed you can just grab it from there.
@@derekfloodVFXyes installed,how?
@@cinemacult1346 locate the NumPy folder in your Houdini install, and copy-paste it to use in place of the numPy folder in my repo.
@@derekfloodVFX module 'numpy' has no attribute 'array'
@@cinemacult1346 I'd suggest you ask on stackoverflow.com. Troubleshooting installing Python modules is a bit beyond the scope of CZcams comments. 😅