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Changing camera angle of a video

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Paritosh SrivastavaChanging camera angle of a video
by on Feb 25, 2016 at 5:53:08 pm

Is there any way to make it look like a video was shot at a slightly higher angle than it was actually shot ? I am new to the forum so be gentle with me, although I have been using after effects for the past 3 and 12 years or so.(probably didn't need to type in the last line.)


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Dave LaRondeRe: Changing camera angle of a video
by on Feb 25, 2016 at 7:36:06 pm

Not really. The perspective change taking place between the two camera heights would reveal new portions of the entire shot, and obscure others. You would have to be able to change those things.

In cases like this, it's best to either live with the shot as is, or re-shoot.

Dave LaRonde
Promotion Producer
KGAN (CBS) & KFXA (Fox) Cedar Rapids, IA


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Paritosh SrivastavaRe: Changing camera angle of a video
by on Feb 25, 2016 at 7:40:07 pm

Just realized, I meant 3 and 1/2 years, and what if I have the subject rotoed out, would that open up any possibilities ? skewing or anything ?


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Dave LaRondeRe: Changing camera angle of a video
by on Feb 25, 2016 at 7:47:32 pm

Keep in mind that the perspective on the subject would also change. Look at a person's face at his/her chin level. Now look at the same person at forehead level. Note what you can see in one, but can't in the other, and vice-versa.

You seek to do a 3D perspective change on a 2D image. If you're not very picky, I suppose it might work. If it has to look photorealistic, it will not.

Dave LaRonde
Promotion Producer
KGAN (CBS) & KFXA (Fox) Cedar Rapids, IA


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Paritosh SrivastavaRe: Changing camera angle of a video
by on Feb 26, 2016 at 10:36:46 am

True sir, perspective change on 2D images can be a daunting task, but you guesses it right here, I am not trying to achieve photo realistic results here. I am really just making a happy birthday video for a classmate who is a really big fan of minions. Thank you all for such quick replies to my question. Cheers.


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Conrad OlsonRe: Changing camera angle of a video
by on Feb 25, 2016 at 7:57:21 pm

It is possible but a lot of work, and you can only go a certain distance before you will start seeing the limits of working with a 2D image. But this is basically what they do when they convert a movie that was shot in 2D into a stereo movie.

If everything is far from the camera you will have much more success than if anything is really close, because there will be less parallax for each object.

The best way to do this is with a 3D solution. I haven't used After Effects for a long time so I can't give you detailed instructions, but I can tell you the technique I'd use in Nuke and hopefully you can figure it out in AE.

The first step is to create a 3D camera track of your shot, then create cards or geometry for every layer you want to separate.

Roto each object and use the tracked camera to project each layer onto it's card or geo. If you render the scene from the original camera you should end up with an identical image to your original.

Now duplicate your original camera and move it to the new position that you would like to view the scene from. Use this new camera to render your scene. You will see everything from a new angle, and you will also see all the gaps where you are now seeing parts of the shot that were occluded in the original angle. You need to use paint techniques to fill all of these gaps. Luckily, having a 3D setup will help with a lot of the paint task but it will still be a lot of work.

If you are only revealing a few pixels you might be able to get away with erodes, or scaling up the fg layer to fill this gaps, but more than a few pixels will require more detailed paint work.

At some point, if you move the camera too far you will be able to see that everything is just 2D layers.

---

conradolson.com


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Paritosh SrivastavaRe: Changing camera angle of a video
by on Feb 26, 2016 at 10:32:18 am

You gave me the basic idea of how to do it.
First I used 3D camera tracker to create a 3D track of the entire scene(which I don't end up using) then I roto out all my subject(in this case, it was just one layer)
Then I looked up, what are cards in Nuke and found out, I won't be needing those as I will be projecting the rotoed layer onto a separate footage.
I saw tutorials on how to animate 2D images into 3D space using PS and AE and that gave me the rest of the missing links that were needed.
So in the end, I didn't do much at all. I just made my rotoed layer 3D, changed its 3D orientation a bit, made a camera layer, raised its height a bit, and boom... it gave me the result I wanted.
So thank you sir, your instructions genuinely helped me.
p.s- the rotoed layer is from the minions movie, illumination studios rendered almost all the minion scenes from their eye level, so I couldn't actually re-shoot.


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