[Pierre Jasmin]

Too many variables to provide exact numbers

Would suggest 5 degrees increments for cameras on an arc (pointing at the same location) shooting someone that is completely in view in terms of framing.

Pierre

[Pierre Jasmin]

Too many variables to provide exact numbers

Would suggest 5 degrees increments for cameras on an arc (pointing at the same location) shooting someone that is completely in view in terms of framing.

Pierre

[Pierre Jasmin]

Good thing that you are over black and there is not multiple layers of stuff.

The faster the action, the better it is to have more FPS (e.g. 30 FPS is better then 24…). In the end it has a lot to do with how much pixels per frame we are traveling from a point in a picture to the destination in another picture.

The workflow with RE:Flex will just be different. It’s more a different UI then a completely different technology. With RE:Flex Morph you have to first place the frames at the right place in time. The auto-align button in RE:Flex is the optical flow switch (is like Twixtor Motion vectors). Each have their own advantages.

The same apply with a person jumping… The part that is usually harder for Twixtor is for example if the persons hands are extended forward towards the camera as it creates more pixels invisible in the other frames. I know it might sound strange but someone with their arms up toward the ceiling is easier (or staying on the body while one twirls) then arms extended forward towards the camera(s)…

Since it’s video cameras, you have the option of first keeping many takes and just run twixtor and see the ones that work best.

For your or someone else info:
1) https://www.breezesys.com/MultiCamera/index.htm has a multi-DLSR remote control. I bought the single camera one for my Canon and it’s OK, but I never tried the Multi-Camera one.
2) are the cameras going to be in synch? If not best you shoot the max FPS you can with it. (e.g. 1/30 time offset is better then 1/24).
It might also be possible to time-aligned them in Twixtor? But something you probably would like to avoid.

I am not sure about 3D camera track, other then if you need to add CG around it. However it’s possible that even if your rig is fixed that when you play back it feels like a shaking camera. So that at least if need be should be stabilized as the first thing. Although it’s probably something you could test run if there is a quick way to dump a take of each camera to a computer. (maybe placing a cube somewhere in the background and see if it wiggles when you play the 20 frames).

Also if you have sequences for each view, it might becomes handy as well (gives you the latitude to have some motion, switch to live-action in-between and continue not just totally frozen time). For example a nice cheat could be that part of the take works fine until some point and then the rest works good from half a second later so you use a view slow-mo to the right speed with Twixtor to switch?

Good luck,

Pierre
RE:Vision Effects

[Pierre Jasmin]

Good thing that you are over black and there is not multiple layers of stuff.

The faster the action, the better it is to have more FPS (e.g. 30 FPS is better then 24…). In the end it has a lot to do with how much pixels per frame we are traveling from a point in a picture to the destination in another picture.

The workflow with RE:Flex will just be different. It’s more a different UI then a completely different technology. With RE:Flex Morph you have to first place the frames at the right place in time. The auto-align button in RE:Flex is the optical flow switch (is like Twixtor Motion vectors). Each have their own advantages.

The same apply with a person jumping… The part that is usually harder for Twixtor is for example if the persons hands are extended forward towards the camera as it creates more pixels invisible in the other frames. I know it might sound strange but someone with their arms up toward the ceiling is easier (or staying on the body while one twirls) then arms extended forward towards the camera(s)…

Since it’s video cameras, you have the option of first keeping many takes and just run twixtor and see the ones that work best.

For your or someone else info:
1) https://www.breezesys.com/MultiCamera/index.htm has a multi-DLSR remote control. I bought the single camera one for my Canon and it’s OK, but I never tried the Multi-Camera one.
2) are the cameras going to be in synch? If not best you shoot the max FPS you can with it. (e.g. 1/30 time offset is better then 1/24).
It might also be possible to time-aligned them in Twixtor? But something you probably would like to avoid.

I am not sure about 3D camera track, other then if you need to add CG around it. However it’s possible that even if your rig is fixed that when you play back it feels like a shaking camera. So that at least if need be should be stabilized as the first thing. Although it’s probably something you could test run if there is a quick way to dump a take of each camera to a computer. (maybe placing a cube somewhere in the background and see if it wiggles when you play the 20 frames).

Also if you have sequences for each view, it might becomes handy as well (gives you the latitude to have some motion, switch to live-action in-between and continue not just totally frozen time). For example a nice cheat could be that part of the take works fine until some point and then the rest works good from half a second later so you use a view slow-mo to the right speed with Twixtor to switch?

Good luck,

Pierre
RE:Vision Effects

[Pierre Jasmin]

So to recap – you have roughly 19 other views and 180 degrees to travel. 180/19 = about 9.5 degrees of rotation per key-image.

In the past what I have seen with such scenario is anything from it works surprisingly well to it’s real hard.

Things to be careful with:
– objects too close to camera
– too many layers of action
(ideally if the foreground was over green screen and this is captured in two passes it removes a lot of such problems).

Technically such problem is related to a large region in an image (more then a few pixels) not visible in the other one when you in-between. What is called an occlusion.

Like last year I helped someone in Europe do something similar to what you describe and two simple lines animated on the background made it look pretty good (was car racers after the race popping champagne frozen time style and the jumping happy car racer at certain angles was creating a lot of warpiness)

But then someone else had a kitchen scene with corridors to other rooms, multiple actors… and that created a lot of roto work.

So, if you shot some tests but not the final yet – I can certainly take a look – sometimes simple thing like a prop at the wrong place transforms a 2 days job into a 2 weeks job… I live at techsupport at revisionfx dot com.

As for 3D cam recon. One thing that would help is to make sure the source stills are stablized – the rotation by itself is smooth as shakes looks weird when slowed-down.

From there what would help is to know the set of software package you have access to. Without going into details, for example in the Softimage version there is a way to capture all the tracking points from the 3D recon. Yet these points are not necessarily more accurate then Twixtor. In Fusion there is a way to link points to such 3D points as well, but it’s a bit more manual, would possibly augmented by scripting. While in many applications our only way to absorb pre-tracking inputs will be via 12 point parameters and mattes for layers… In some cases, this becomes a form of assited morph job and the RE:Flex workflow (which includes our morphing tool) might be more appropriate then Twixtor.

I imagine these are digital SLR cameras. Another small concern is color stability across frames. It used to be much harder in photographic film days as precautions such as using all the same stock and film processing bath.. were advised. Exposure is also an issue – I have helped in the past someone do long exposures still capture rig to timewarp with long trails, that’s a completely different issue then having the smallest exposure possible (smallest amount of motion blur or depth of field to start with – specially if you have specular highlights reflections… specular highlights reflections can be undoable (well paint job) and combined with DOF effect also have diffraction properties you probably want to avoid.

Finally 180 degrees is ambitious, 90 degrees rig with 20 cameras tend to be easier to interpolate without transforming this into a morph job. I am not sure about the callibration and capacity of your camera AND what you are trying to capture but one trick if there is an actor involved is to have the first or last camera that shoots continuous instead so you can have say an actor jump with a related rotation at the start. However say your first or last camera can shoot continuous 6 FPS then your effect would need to be designed so for example the action starts real fast and speed ramps towards real slow to end in a freeze…

Pierre
RE:Vision Effects

[Pierre Jasmin]

So to recap – you have roughly 19 other views and 180 degrees to travel. 180/19 = about 9.5 degrees of rotation per key-image.

In the past what I have seen with such scenario is anything from it works surprisingly well to it’s real hard.

Things to be careful with:
– objects too close to camera
– too many layers of action
(ideally if the foreground was over green screen and this is captured in two passes it removes a lot of such problems).

Technically such problem is related to a large region in an image (more then a few pixels) not visible in the other one when you in-between. What is called an occlusion.

Like last year I helped someone in Europe do something similar to what you describe and two simple lines animated on the background made it look pretty good (was car racers after the race popping champagne frozen time style and the jumping happy car racer at certain angles was creating a lot of warpiness)

But then someone else had a kitchen scene with corridors to other rooms, multiple actors… and that created a lot of roto work.

So, if you shot some tests but not the final yet – I can certainly take a look – sometimes simple thing like a prop at the wrong place transforms a 2 days job into a 2 weeks job… I live at techsupport at revisionfx dot com.

As for 3D cam recon. One thing that would help is to make sure the source stills are stablized – the rotation by itself is smooth as shakes looks weird when slowed-down.

From there what would help is to know the set of software package you have access to. Without going into details, for example in the Softimage version there is a way to capture all the tracking points from the 3D recon. Yet these points are not necessarily more accurate then Twixtor. In Fusion there is a way to link points to such 3D points as well, but it’s a bit more manual, would possibly augmented by scripting. While in many applications our only way to absorb pre-tracking inputs will be via 12 point parameters and mattes for layers… In some cases, this becomes a form of assited morph job and the RE:Flex workflow (which includes our morphing tool) might be more appropriate then Twixtor.

I imagine these are digital SLR cameras. Another small concern is color stability across frames. It used to be much harder in photographic film days as precautions such as using all the same stock and film processing bath.. were advised. Exposure is also an issue – I have helped in the past someone do long exposures still capture rig to timewarp with long trails, that’s a completely different issue then having the smallest exposure possible (smallest amount of motion blur or depth of field to start with – specially if you have specular highlights reflections… specular highlights reflections can be undoable (well paint job) and combined with DOF effect also have diffraction properties you probably want to avoid.

Finally 180 degrees is ambitious, 90 degrees rig with 20 cameras tend to be easier to interpolate without transforming this into a morph job. I am not sure about the callibration and capacity of your camera AND what you are trying to capture but one trick if there is an actor involved is to have the first or last camera that shoots continuous instead so you can have say an actor jump with a related rotation at the start. However say your first or last camera can shoot continuous 6 FPS then your effect would need to be designed so for example the action starts real fast and speed ramps towards real slow to end in a freeze…

Pierre
RE:Vision Effects

[Pierre Jasmin]

In general you need a greyscale noise generator,
followed by some blur (like SmoothKit Gaussian, the amount of blur will change the size of the video noise),
followed by some color correction that restrech out the black and white. That gives you moving video like noise.

and then if you want video snow then you need to blend that into your image

I think DigiEffects has a product called Damage that has such receipe built-in for that.

Pierre

[Pierre Jasmin]

In general you need a greyscale noise generator,
followed by some blur (like SmoothKit Gaussian, the amount of blur will change the size of the video noise),
followed by some color correction that restrech out the black and white. That gives you moving video like noise.

and then if you want video snow then you need to blend that into your image

I think DigiEffects has a product called Damage that has such receipe built-in for that.

Pierre

[Pierre Jasmin]

To know what software/hardware you have would be useful.

One of the key to straight forward chroma keying is proper uniform lighting of the green screen.

A second variable is the type of camera and compression method used:

a) video noise (a lot of CMOS cameras tend to produce noisy video under not enough lighting)

b) the way the camera + codec ends up encoding chroma subsampling
– for example 4:2:0 with fields as a capture method for keying is probably asking for trouble (might create hard to get rid of fringes on the key edges)
see https://en.wikipedia.org/wiki/Chroma_subsampling
as a reference for “chroma subsampling”

Pierre
RE:Vision Effects

[Pierre Jasmin]

To know what software/hardware you have would be useful.

One of the key to straight forward chroma keying is proper uniform lighting of the green screen.

A second variable is the type of camera and compression method used:

a) video noise (a lot of CMOS cameras tend to produce noisy video under not enough lighting)

b) the way the camera + codec ends up encoding chroma subsampling
– for example 4:2:0 with fields as a capture method for keying is probably asking for trouble (might create hard to get rid of fringes on the key edges)
see https://en.wikipedia.org/wiki/Chroma_subsampling
as a reference for “chroma subsampling”

Pierre
RE:Vision Effects