Need help with face-replacement in a video.

[surferadi96]

Here's the thing:

I want to replace the face of the person in a video with the IMAGE of someone else's face.
I have both Photoshop and After Effects.
I do know about motion tracking, key-framing, masking etc.

But the problem is the perspective change of the persons head in the video.
i.e. the person in the video is moving his head from left to right.So, how do i show the change in perspective in the replaced image of the head?

[poisondeathray]

Here's the thing:

I want to replace the face of the person in a video with the IMAGE of someone else's face.
I have both Photoshop and After Effects.
I do know about motion tracking, key-framing, masking etc.

But the problem is the perspective change of the persons head in the video.
i.e. the person in the video is moving his head from left to right.So, how do i show the change in perspective in the replaced image of the head?

You can 't do a realistic job with this , because the source image is 2D photo (flat, planar) in 1 projection. Even if you used a 3D tracker / matchmover with a true 3D program, you need better source material , with multiple projections or images showing different perspectives

[budwzr]

Like mentioned above, it's not easy, but to answer your question, try pressing ALT or CTRL while you're resizing the photo.

[surferadi96]

Here's the thing:

I want to replace the face of the person in a video with the IMAGE of someone else's face.
I have both...

You can 't do a realistic job with this , because the source image is 2D photo (flat, planar) in 1 projection. Even if you used a 3D tracker / matchmover with a true 3D program, you need better source material , with multiple projections or images showing different perspectives

I do have images with different perspectives (like head facing towards left, right, front etc.).
Do you mean a 3d model of the head when you refer to a "better source" ?

[poisondeathray]

I do have images with different perspectives (like head facing towards left, right, front etc.).
Do you mean a 3d model of the head when you refer to a "better source" ?

Yes, but those are 2d mapped, you need UV mapping with 3d coordinates

http://en.wikipedia.org/wiki/UV_mapping

Or use 3D projection techniques

After Effects isn't the right tool for this because it's not true 3D (it has 3D space, but they are 2D layers in 3D space . It's really "2.5 D") . The motion trackers in AE are 2D, not 3D. Even mocha is planar. You can use 3rd party 3d trackers (e.g. foundry camera tracker) , but it still integrates into AE with 2d layers in 3d space. In other words, you need your replacement photos of the "head", to be in near perfect alignment as the source "head"



You manually try to fake it in AE, by adding small adjustments distortions, with motion tracking, but it won't look authentic (or it will takes weeks of fiddling) . If your replacement images are in perfect aligment, then it makes it easier. But if you only have left, front, right and nothing in between, you are missing a lot of data

[budwzr]

Faking 3D can only be attempted when the object has "bilateral symmetry", and you're on a "normal" viewing angle, as in straight on at the same elevation.

What you do is make a copy of the image and rotate the copy 180 degrees, then bring both objects together so they bisect in the middle forming an "X" if you were to look down on them.

Then when you rotate the camera, there will be a rough 3D effect. This is useful for like trees that are in the background.

But since the face is going to get watched closely, it's not going to look realistic at all.

[surferadi96]

I do have images with different perspectives (like head facing towards left, right, front etc.).
Do you mean a 3d model of the head when you refer to a "better source" ?

Yes, but those are 2d mapped, you need UV mapping with 3d coordinates

http://en.wikipedia.org/wiki/UV_mapping

Or use 3D projection techniques

After Effects isn't the right tool for this because it's not true 3D (it has 3D space, but they are 2D layers in 3D space . It's really "2.5 D"

You manually try to fake it in AE, by adding small adjustments distortions, with motion tracking, but it won't look authentic (or it will takes weeks of fiddling) . If your replacement images are in perfect aligment, then it makes it easier. But if you only have left, front, right and nothing in between, you are missing a lot of data

Thanks for the advice.
I will just work my way around inside of after effects(as im not that good in the 3D part) to get this work done because attaining realism in the replacement is not my motive as the video is going to be humorous.

[surferadi96]

Faking 3D can only be attempted when the object has "bilateral symmetry", and you're on a "normal" viewing angle, as in straight on at the same elevation.

What you do is make a copy of the image and rotate the copy 180 degrees, then bring both objects together so they bisect in the middle forming an "X" if you were to look down on them.

Then when you rotate the camera, there will be a rough 3D effect. This is useful for like trees that are in the background.

But since the face is going to get watched closely, it's not going to look realistic at all.

Yes, i agree with you.Its not going to look realistic.
For the change in perspective, i will use the images of the head in different angles.
Though this might look choppy, but this is the only way it can be done i guess.

[poisondeathray]

I will just work my way around inside of after effects(as im not that good in the 3D part) to get this work done because attaining realism in the replacement is not my motive as the video is going to be humorous.

If you're not wanting it to look realistic, this is achieveable, but again the tools built in AE or mocha don't account for 3D rotation (they are 2D point , and planar tracker for mocha ) - so you end up having to manually do some roto work and manually adjusting some of the images



Funny is good - Do you remember those "this is sparta" youtube videos ? hilarious

[surferadi96]

I will just work my way around inside of after effects(as im not that good in the 3D part) to get this work done because attaining realism in the replacement is not my motive as the video is going to be humorous.

If you're not wanting it to look realistic, this is achieveable, but again the tools built in AE or mocha don't account for 3D rotation (they are 2D point , and planar tracker for mocha ) - so you end up having to manually do some roto work and manually adjusting some of the images



Funny is good - Do you remember those "this is sparta" youtube videos ? hilarious

lol..XD
Just saw it today!

I'm planning on making something similar
This will require a lot of work though.
Will have to do manual positioning, scaling and rotation for most of the video.

[poisondeathray]

Yes, more manual work unfortunately. Good luck.

Post a link your finished video!