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tiff image jitter with virutal camera movment

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viking jonssontiff image jitter with virutal camera movment
by on Aug 21, 2012 at 8:32:50 pm

Hello,

I'm helpin out a little bit on a project where stills and video is comped together.

In the project there is a virtual camera movement and when the camera moves the still image (tiff) jitters.
It looks pretty strange cause it dosen't go together with the video tracks.

I tested this following solutions:

1. Add directional blur, it seems to help but the image gets a bit to soft.
2. Add reduce interlace flicker, same effect there. I guess it just looked better cause of the softness.
3. Render the still as separate field upper and lower, didn't work.
4. Pre-comp the still image, and make the pre-comp to have 4 times as high frame rate as the original comp. Wich I thought was going to help cause of the slow "change of frame" in the still image.


I read a five year old post here on CC that this phenomenon can happen when a virtual camera is moving across a still image and it can only be fixed with a bit more random movement in the camera move or to change the speed of the camera wich I don't want to do.. but that was five years ago I'm sure there is a solution now a days

Is there any other way that will fix this problem, with out using a blur?

Thank You

Viking Jonsson


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Dave LaRondeRe: tiff image jitter with virutal camera movment
by on Aug 21, 2012 at 8:39:51 pm

What's the vertical & horizontal resolution of the still? You may have it scaled or moved in z-space to the point where some lines are less than 1 pixel wide. That's not good for movement.

A quick, but not always reliable fix: add a tiny amount of blur to the still.

Dave LaRonde
Sr. Promotion Producer
KCRG-TV (ABC) Cedar Rapids, IA


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viking jonssonRe: tiff image jitter with virutal camera movment
by on Aug 21, 2012 at 8:52:54 pm

[Dave LaRonde] "What's the vertical & horizontal resolution of the still? You may have it scaled or moved in z-space to the point where some lines are less than 1 pixel wide. That's not good for movement."

Thanks for the tip!

The image resolution is about 1300x1600. I can't change the scale.
I've tested the blur and it didn't work for me unfortunately :'(

Is there any plug-in or other good ways to tackle this?

Thank You
Viking Jonsson


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Dave LaRondeRe: tiff image jitter with virutal camera movment
by on Aug 21, 2012 at 8:58:02 pm

"Jitter" is a pretty nebulous term, but it commonly means the image is moving back in forth at a very high rate. If you mean something else, please describe it in greater detail for diagnostic purposes.

Dave LaRonde
Sr. Promotion Producer
KCRG-TV (ABC) Cedar Rapids, IA


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viking jonssonRe: tiff image jitter with virutal camera movment
by on Aug 21, 2012 at 9:08:43 pm

The virtual camera movement over the stills image dosen't look smooth, some part where it is high contrast its really noticeable. It goes back and forth in a small pattern during the key-framed camera move.


I'm afraid I can't explain it better then that.

I'm really thankful for You advice.

Thank You
Viking Jonsson


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Walter SoykaRe: tiff image jitter with virutal camera movment
by on Aug 21, 2012 at 9:55:17 pm

Have you tried motion blur instead of directional blur?


[viking jonsson] "I read a five year old post here on CC that this phenomenon can happen when a virtual camera is moving across a still image and it can only be fixed with a bit more random movement in the camera move or to change the speed of the camera wich I don't want to do.. but that was five years ago I'm sure there is a solution now a days"

Linking to the post you're referring to would help me understand a bit better, but what I think you are referring (judder) to is actually endemic to all cameras, both virtual and physical, and is not a solvable problem. It is part of the nature of cinematography.

See Avoiding Judder in Motion Graphics [link] for more.

Walter Soyka
Principal & Designer at Keen Live
Motion Graphics, Widescreen Events, Presentation Design, and Consulting
RenderBreak Blog - What I'm thinking when my workstation's thinking
Creative Cow Forum Host: Live & Stage Events


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chris brettRe: tiff image jitter with virutal camera movment
by on Aug 21, 2012 at 11:35:35 pm

Hi there -----


--- as Walter points out there are some combinations of scale and speed that just do not go with the frame rate and will always jitter however there is almost always something that can be done that makes the job ok ...... though sometimes it takes a lot of tweaking to get it quite right ....

I am clutching at straws a bit as I havent seen the footage but if you havent already tried these its worth considering the following I think .....

1 ) -- if in fields make sure the field order is the correct way round

2 ) -- if that does not work try merging the fields so it is frame based

3 ) -- this one is pure superstition but I had weird things with tiffs once that were solved by taking the frame into Photoshop and converting it to a targa ( at least I think it what solved it ! )

4 ) -- try shifting either the camera of the frame 1 notch in z space ...

.... again a bit superstitious by if I have a field problem I always like to make sure I'm on even numbers ... so shifting it one notch puts it on an even number if it isnt already ... you wont see the size difference.....

5 ) -- same on the y axis


6 ) --- and obvious stuff / check how you are viewing the end result - is it at 100% ?


.......... these checks should clear up the issue if it a 'glitch' but if the problem persists I expect it is a technical issue as described by Walter in which case my preference would probably be to keep the still in interlaced fields and add motion blurr .




ALSO ( this can be a useful trick ) I have, in the past, modified selected parts of a difficult frame using a mask or in photoshop.

This technique will probably help in your high contrast areas which are proving difficult ( if the fixes as above do not work )...


In photoshop you can selectively and artisticly ( ? )blurr out offending areas with great accuracy - and to varying degrees as well which can be useful.

If done carefully this should not be too noticeable so that by the time you get it back into AE and add a wee bit of motion blurr it becomes 'passable'.

I did this once and burred the heck out of just a few edges that were really jittering but it looked ok in the comp because everything else appeared sharp.

Also best remember that you know this problem exists therefore you tend to notice it .... if a few selected ( tiny ) areas are soft no one else is likely to notice it - and probably not even yourself if you were new to the job.


If going down this route using selected blurring really precisely is what pays off ... pick on the offending black line ( say )where it looks worst and blurr it to the point that when the motion blur is added as well it looks ok.

Anyway thats my tuppence worth ... I wish you well on this one .. I know it can be most infuriating.....



-------------- chris brett // uk


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