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I have little-to-no prior video editing experience, but am trying to edit together a video from when a friend and I flew in a full-motion flight simulator for a website.

I shot the video with my DSLR, but unfortunately the frame rate of my DSLR was apparently very close to that of the simulator's projector, which resulted in visible yellow lines moving across the video from bottom to top somewhere around once or twice per minute (presumably the projector's scan lines.)

Unfortunately, re-shooting the video with a different frame rate isn't really a feasible option in this case, as I'd have to travel again to the city with the simulator and it also costs a small fortune to rent it even if I were there. If I had thought about this problem, I'd have shot in a different frame rate the first time, but I unfortunately didn't notice it until after the fact (I was a bit too busy flying the plane to review the video in real time.)

The lines look like this:

Image of scan line on simulator's sky #1
The curved yellow line on the runway is supposed to be there. The straight yellow line across the sky is what I'm trying to get rid of.

Image of scan line on simulator's sky #2
Again with the straight yellow scan line across the sky ruining the scene. Note the relatively featureless sky.

What I've done, so far:

I'm editing the video in DaVinci Resolve 15 (the free version, which now also includes Fusion) and am trying to get rid of the lines as much as possible.

I can get a key on the lines without too much trouble using Resolve's qualifier tool in combination with a power window and the tracker.

Here are the strategies I've tried for getting rid of the line after keying it:

Color Correction Curves

I've tried using color curves (especially hue vs. saturation and hue vs. luminosity) to remove the yellow hue and match the brightness to the scene. This works well enough for when the line is passing over the ground, as I can turn the line into a shade of grey or white that blends in very well with the ground scenery (white in the case of the runway stripes/numbers, grey otherwise.)

Unfortunately, however, my tinkering with the color correction wheels and curves hasn't been able to produce anything that blends the line well with the sky. I can git rid of the yellow hue easily enough, but I don't know enough about video color correction to get the result to be something that blends in with the white and blue in the sky. I just end up with a grey or black line across the sky instead of a yellow one, which is still no good.

Match Move with a Matte

I've also tried creating a matte by exporting a still of the scene when the yellow line was not passing over the sky. I then fed the matte into a Match Move node and had the Match Move track the scene in order to get the proper scaling, panning, and rotation on the still as the scene progressed (the airplane is pitching, rolling, and yawing a bit, so the sky moves around.) I then keyed the line in the video, inverted the key, and fed both the clip with everything but the line being keyed and the match-moved matte into a layer mixer node so that the line was replaced with the image of the sky behind it.

My node graph for this setup looked like this:

Resolve node graph for match move

(The key mixer shown is being used in order to blend a few different qualifier and power window based keys together in order to fully track the line as it moved across different colors.)

This strategy worked alright for some of the scenes, though some of the other scenes contained skies that were so featureless that the tracker in the Match Move node refused to track the sky. It would either never track at all or only track 2-3 frames and then give up. Unfortunately, tracking the terrain instead wasn't really an option, as the jet was moving across the terrain quite quickly (and, even when I did try that, the terrain was also rather featureless and not being tracked well.)


So, what strategies would you recommend for getting rid of these lines?

If I could just blur the lines into their surroundings enough to not be noticeable, that would be great, but I'm too much of an editing/color correction novice to know how to do that properly (especially for the sky.)

If there's something in Fusion I could use to get a decent track on the mostly-featureless sky, apply that track to a still without the line, and then composite the video with the lined alpha-ed out on top of the still, that would be great, too.

  • Also, if there's a relevant tag I'm missing or I've misused a tag, feel free to correct it. Like I said, I'm new to video editing, so I'm not familiar with all of the proper terminology. – reirab Nov 21 '18 at 2:33
  • It really depends on the footage. Is the camera moving relative to the screen? If it is, how much? If it's not moving that much and there's enough external reference (the corners of the screen, dirt on the screen, static objects in the periphery, e.g.) you could stabilize the camera and then just keyframe the position of a linear gradient matte to match the movement of the stripe. I imagine the stripe moves at a constant velocity and cyclicly, so the hard part is stabilizing the camera. – Jason Conrad Nov 21 '18 at 7:14
  • @JasonConrad The camera does move some relative to the screen (it was just being held, not mounted, and this was a full-motion sim.) The sky image also moves quite a bit relative to the screen, since it's simulating flight. There's a few degrees of rolling and pitching and a bit of yawing as well. So, the dirt on the screen and windshield move relative to the sky. – reirab Nov 21 '18 at 9:08
  • Right. Like I said, it's hard to know without actually looking at the footage. But theoretically you can forget about the simulation image because the artifact is tied to the real-world, not the simulation. Sure, it moves, but its movement is a function of the relative positions between real-world objects and their independent frame rates. And, just to be clear, when I say dirt, I don't mean simulated dirt on the virtual cockpit windshield, I mean a real-world imperfection on the projection screen. VFX artists use tracking markers, but you'll have to work with what's available. – Jason Conrad Nov 21 '18 at 15:34
  • Also, I should probably say that matchmoving, keyframing, etc are pretty tedious processes which require a LOT of tweaking and refinement under the BEST of circumstances. Applying those practices here -- especially over durations over a few seconds -- sounds positively masochistic. I'd only try it if you're looking for a challenge (I'm always making things harder than they need to be for this reason, so take my advice with a grain of salt). But if you just need to get it done, spend your energy looking for another solution. Maybe an OFX plugin? – Jason Conrad Nov 21 '18 at 15:53

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