Hi there,
I've been playing with rendering different passes and learning what I can change after the render is done but for the life of me I cannot figure out what the use case is for a position pass? 🤔
I tried researching a bit but didn't find anything that could help me understand, and the Blender manual is not very descriptive:
"Position
World position of objects in the scene." Lol
What does it do? Do you have any resources to recommend?
Thanks!
Sean will know best, but if I remember correctly, you can use it motion blur stuff? Maybe blur elements by their distance to the camera? Also maybe for matte's? If you want to key out a specific object. Since with it you know how far away where where exactly an object is in relation to the world.
There is a very old but super good in depth compositing videos playlist from Bartek, he used to do the compositing tutorials on CG Cookie and he was super technical in his explanations. They still hold up super well and its a fountain of knowledge. Linking you up:
https://www.youtube.com/watch?v=8Pn6C4ZDjd8&t=1s
https://www.youtube.com/watch?v=Gq5YWSpvME8&list=PL_hh_NWkLF6OMkhfOGX8StK9iSm91JBV6&index=5
https://www.youtube.com/watch?v=h2UnvgqXqLc&list=PL_hh_NWkLF6OMkhfOGX8StK9iSm91JBV6&index=1
Thanks Omar! I'll definitely give it a watch, I'm sure the concepts still hold true. Mostly what I see is the step-by-steps changing with different Blender versions.
I thought that would be that too! And maybe it's a different way of achieving that, other than the Z pass? I render it and get RGB colors, but not sure what to do with them yet 😅
Hi Nathalia,
I don't know either what that does, but I remember Chuck Baking Position in the Tread Course: https://cgcookie.com/lessons/baking-texture-maps
He probably explains what it's for (but I forgot)...
I only know of people using it with Nuke. In which case, it is used to know the world's XYZ(RGB) location of each pixel of the image. This way Nuke can determine when Objects move behind or in front of elements that are coming from multiple sources.
Oh, that makes sense! I wonder if that would translate somehow to After Effects... I'm not Nuke smart. lol.
Though for that I just transfer depth info with empties and a little python script, or use cryptomattes.
Not sure how it would apply to the inside Blender compositing workflow... probably same as with Nuke, since we can't move things behind the others like we can with layers. Maybe for compositing other effects, or if I brought in pre-rendered text animations to add to the scene. 🤔
It allows you to create mask/alpha areas on deforming objects. And yeah, I've only ever used it in Nuke, it would be great to see it working in Blender! I'll add that to my ever-growing list of things to do tutorials on, haha!
It basically assigns a pixel value (using those RGB colors you're seeing) to every point on a model BEFORE it's animated or deformed. So, you could pick an area on say, a character's hand, tell it how big to make the area and feather the falloff, and use that as a matte to adjust the color of the character's hand.
Here's a video I found of someone showing it in Nuke.
https://youtu.be/FkZKy51P5nY?si=Kjus7ZbPBaW06oeB
The never ending list! Lol.
Thanks Sean! That makes it pretty clear! I don't think my After Effects workflow would need that kind of pass then... but I'll keep an eye out for any future tutorials from your list! I'm doing a little personal project and just rewatched a couple chapters from the compositing course because I'll try and keep it all in Blender this time!!