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Nickwhy90
Known Participant
May 24, 2023
Question

How to Turn a Video file to a Sequence of EXR Files for Depth Compositing?

  • May 24, 2023
  • 4 replies
  • 5064 views

Hey guys,

 

I'm still working on a project that I posted about a few weeks ago and now I have a new issue that I can't figure out.

 

Could you give me an andvice how I can convert a mov/mp4 video into an EXR sequence of files? I'd like to add an explosion when the missle hits the ground and want to make the flying of concrete pieces more realistic through some depth compositing. Currently as it is, I see that making layers 3D and moving them along the Z axis is not going to do the job.

 

I've searched online convertors and ways to do it within AE/Premiere, but with no luck. All tutorials that I've seen about depth compositing with EXR files, feature the video file in the format of a EXR sequence, so the tutorials get straight to business with the 3D Channel EXtractoR effect . I see that it's possible to export exr passes from 3d software like Cinema 4D, but theo nly way i see to import a video there is by creating a new material and add the video as texture, then add it to a plane object , but it doesn't play (I don't have experience with Cinema 4D). 

 

The only way I found was to export a video file as a png sequence, then convert it via an online converter, but it allows conversion of only 1 file at a time, and there are a lot of them, so it's not worth it. I used only 1 png-turned exr file to test if I can get the passes somehow and copy them to the .MOV layers with the exploding asphalt, but I guess it can't work that way. 

 

I've attached a preview play of the scene so you can see the current state.

 

As always, any help is highly appreciated.

 

Nik

This topic has been closed for replies.

4 replies

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Nickwhy90Author
Known Participant
May 25, 2023

Thank you all for your inputs!

 

So in general, I would have to import the video file I have with the helicopter and the landing track into Cinema 4D and export it into an EXR sequence, correct? Could you give me a hint how that could be done, since like I explained in my original post, I just can't import the video file into the program, nothing happens when I drag and drop it asa MOV file. As an mp4 file, it says "unknown filke format".

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Filip23315833k75u
Inspiring
May 25, 2023

No. When we said you need a 3D application we meant you have to build the entire scene in 3D and render it - you know, make the 3D animation/movie yourself. If you already have a movie clip ready in MOV, there is nothing you can do - it's just a flat piece of image - like a polaroid picture. You will never get it back to a 3D state for depth compositing.

All you can do is do the trick with moving layers in Z axis, but first you have to split your source image into many layers, each layer containing a single object, then you can put each layer at a diffferent ZDepth - that is most likely a lot more roto work than you're willing to make 😕😕

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Nickwhy90Author
Known Participant
May 25, 2023

Got it, thanks. That was my other supposition. Unfortunately, at this moment I don't have any experience with 3D software, so I guess I'll have to do the alternative option, which you suggested. Would this variant also deliver a similar result - I duplicate the ground exploding layer a few times, do some masks here and there to hide certain parts of the flying rock, so it would look more random, and place each layer at a different point on the Z axis. I should have at least 2 layers in front of the fire and smoke explosion, one a bit closer to the camera, the one a bit closer to the fire/ Then I try to add just a little more darkness to the layer that is closer to the camera (farther from the fire explosion) as most amount of light is thrown to the rocks that are closest to the fire.

F
Filip23315833k75u
Inspiring
May 25, 2023

Depth compositing works exlusively with footage rendered from 3D applications.

There are some ways to make the software guess a depth pass from real video footage but so far all of these solutions were wonky and the depth pass generated was more of a gimmick than anything you can actually use in compositing 😕😕 Still waiting for the day that it will finally work - fingers crossed for AI 😉

Mylenium
Mylenium
Legend
May 25, 2023

There is no depth in your video, so there's nothing to gain with whatever obscure conversion procedures. You are wasting your time. Even if you convert it to EXR it won't magically generate depth. the file would need to be re-rendered from the 3D program with that in mind in the first place and even then you have some shopping for plug-ins to do to actually be able to use that info in AE. It's notoriously ill-equipped for that kind of VFX compositing.

 

Mylenium

R
Community Expert
Rick GerardCommunity Expert
Community Expert
May 24, 2023

A video file or image sequence can only contain red, green, blue, and alpha channel information. There is no more information to extract. If you want EXR sequences from an app capable of generating EXR files, you must create them there. 

 

The EXR workflow in After Effects allows you to use the different EXR channels to combine images. Have you looked at any of the tutorials or the EXR Workflow in the User Guide?

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Nickwhy90Author
Known Participant
May 25, 2023

To be honest, I don't learn technical information from text tutorials, I mostly look for videos, because when I see how things are actually done, I learn easier and quicker, which important for me, as I don't have much time. I'm checking now what you gave me,but I don't get how that could help in this situation, or was your purpose just to help me understand how the different effects work, given what you said about the RGB channels?

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