Time remapping, ramping causing choppy video

[JonathonDean]

I've been shooting real estate with my drone and a lot of the footage needs to be sped up, slowed down, or ramped up or down.  When I do this and export the video, the final product seems to be skipping frames ever so often on any clips which the speed is altered.  My most recent issue was shot at 1080 30fps h.264.  The opening clip I'm approaching a property at 200% speed and as I get closer, I ramp back down to 100%.  Those first 10 seconds are really hard on my eyes.  Any ideas what may be causing this?  Is there anything I can do to smooth this out? 

[R Neil Haugen]

Think of what's going on here ... you're getting closer to the center items of the video. So ... things are getting bigger. Then you double the speed of approach, so things are changing size twice as fast. But you're still only able to end up with 30 frames per second.

Each frame, at the base motion of the drone plus 200%, is a lot closer than the preceeding frame.

What is most notable is the "sharpness" of the jumps. One of the factors of being "cinematic" is the amount of natural blurring during panning and motion, that at times saves our eyes & brains from having to process too much data too fast. Perhaps you need to apply some frame-blending, or optical flow, which might smooth things ... or add a small amount of perhaps Motion Blur effect to the speed-ramped sections.

Neil

[JonathonDean]

That makes sense.  I tried applying optical flow to that clip and it destroyed the line detail in the roof.  I'll try some different settings with the remapping and see if it cleans up at all.  I didn't consider the motion blur, I'll give that a shot as well. 

Is there anything I can do on the camera side to allow for easier time remapping in post? 

Thank you very much for the reply, this has been bugging me for a while.

[R Neil Haugen]

Getting a "proper" feeling of motion without either too much "jumpiness" from too-sharp images or too much blur is part of learning the craft. Including things like not zooming past something too close as that exacerbates the problem. So ... a bit more altitude over that initial pass would have resulted in less jarring motion visually ... but with a smaller image of the buildings.

Being able to have that much high-frequency detail go by that fast ... without someone wanting to lose their lunch ... ain't easy. You'll maybe find that you need to both adjust what you do in filming, and how you treat the media in post. Try the different frame blending options, try Motion Blur (which I know is used by some drone folks), and try the various settings. I'd also check what the folks on some of the drone forums say to do with this sort of issue.

Neil

[R Neil Haugen]

Just watched another tutorial on drone shooting. Had a couple things might be of use ...

First, they say, in order to keep from having a lot of eye-troubling flickering, if you're moving forward over something as your main motion, shoot in 23.97/24 whenever possible to get a bit blurrier ... and smoother/more cinematic and less visually troubling footage. Shooting at 29.97 & up while flying over trees & roofs with all that detail will be jumpy or "flicker-jeebies" ... period. Unless your drone is WAY up ... and probably, your drone won't really get high enough.

Second, when the drone is in motion ... unless it's way high up, do NOT "tip" the camera up or down, as that will also get flicker-jeebies.

Just ... fyi.

Neil

[Steliana22571041fiea]

Optical flow fixed it for me. No highly detailed textures (like a roof) in my video though.

[Kevin-Monahan]

Hi JonathonDean,

Sorry for this issue. Did you ever find a solution? Please let us know if you have or if you still need help.

Thanks,

Kevin

[gabriel1992]

Try using ''Optical Flow'' before rendering

It may help

Gab Larkin