8 Replies Latest reply on Oct 21, 2015 7:57 AM by adamneer

    Can AE smooth out motion jitter in tracking shot.

    lasander Level 1

      Hello

       

      I have a tracking shot filmed with a Blackmagic Design Cinema Camera, I tried filming it with alternate shuuter sppeds but every time there is an unpleasant motion blur and jutter to the image, not to be confused with  the smoothness of the tracking shot which is fine.

       

      Have a look...

       

      Blackmagic Motion Test - YouTube

       

      I realise I'm being pedantic but it bothers me... Is there anything that can be done?

       

      Many thanks,

      Liam.

        • 1. Re: Can AE smooth out motion jitter in tracking shot.
          Rick Gerard Adobe Community Professional & MVP

          There's a thing called critical panning speed and you are basically hitting it. The problem is more pronounced at 24 fps than it is at 29.97. The judder is caused by the stroboscopic effect of the motion and the frame rate.

           

          A good cinematographer with experience knows these critical speeds and avoids them. The shutter speed (shutter angle) will not fix the problem. You either have to change the speed of the camera move or do your project at a higher frame rate. If the entire project is to be 24 fps then you must change the speed of the camera move. The ASC cinematographers handbook has a chart. It's important to note that this critical speed is important to know when you are creating motion graphics. Here's an explanation that I wrote for this forum the problem from the AE FAQ section of this forum: FAQ: Why does horizontal motion stutter (judder) in my movies, such as during pans?

           

          Here's a few references from the web.

          Panning Speeds for framerates at 180° shutter

          Cinephotography Tools - Panning Speed

          Panning Best Practices

           

          Unless it's specifically required by the client I shoot all of my video, and even when I shot 35mm film for television when we were shooting film, I ran the camera at 29.97 fps to give myself more options on the set and reduce the likelihood that I would end up with this problem. BTW, you see this all the time in the theater and most of the time you just accept it.

           

          One more note, you can't fix the problem by shooting at a higher frame rate and then putting that shot in a 24fps comp. The problem is movement and playback frame rate causing a stroboscopic effect.

           

          BTW you can prove this to yourself by importing your clip into AE then creating a new comp from the clip. Set the a position keyframe at the first frame of 0,540 at the first frame and then setting the position to 960, 540 at the last frame to change the speed of the movement. The problem will almost completely go away because you have changed the speed of the move.

          • 2. Re: Can AE smooth out motion jitter in tracking shot.
            lasander Level 1

            Many thanks for your comprehensive answer! And yes, I see it all the time too... Still hate it!

             

            Not sure if I understand the last part of your message, can the problem be corrected in post or was your point to illustrate how it can be avoided.

             

            Thanks,

            • 3. Re: Can AE smooth out motion jitter in tracking shot.
              Rick Gerard Adobe Community Professional & MVP

              If your entire project is 24 or 25 fps then you are kind of stuck with the shot. If I have a shot that I think may have these kinds of problems I'll shoot at 60 (59.94) on set and then retime the shot in post to fix the problem and worry about the sound later. My suggestion at the end of the post will just show you what your shot would look like if the speed of the motion was cut in half. You'll have black edges to deal with so there is not much of an easy fix. Changing the frame rate or time remapping may give you some slightly better results but the problem won't go away unless you reshoot the shot.

              • 4. Re: Can AE smooth out motion jitter in tracking shot.
                lasander Level 1

                I see.... Many thanks, appreciate your help.

                 

                Cheers.

                • 5. Re: Can AE smooth out motion jitter in tracking shot.
                  Arivl Level 1

                  Rick is largely correct, but there is a definite relationship between shutter speed (shutter angle) and the prevalence of the effect.   Past a certain point, you'll be stuck with it, but on a shot like this, you can definitely reduce its appearance by switching to a 360° shutter (if you're reshooting) or adding motion blur in post. 

                   

                  Try applying the "timewarp" effect with the speed set to 100% and fiddle with the motion blur settings to add just a bit to your image.  I think you'll see a pretty substantial improvement.  It won't totally fix the problem, but it'll improve it.

                  • 6. Re: Can AE smooth out motion jitter in tracking shot.
                    lasander Level 1

                    Thanks, unfortunately I'm shooting with the Blackmagic Design Cinema Camera and there is no 360 degree shutter option... Motion blur would be fine but I want to people to read the tshirts in the shot.

                     

                    Thanks for your response.

                    • 7. Re: Can AE smooth out motion jitter in tracking shot.
                      Rick Gerard Adobe Community Professional & MVP

                      Shutter angle has little to do with the stroboscopic effect caused by the panning speed and frame rate. It just increases the motion blur. Motion blur does not make the judder to away it just masks it a bit. I'd reshoot at 30 or even 60 and then use time remapping to adjust the speed in post if you can't fix it by time remapping the original shot. Shooting at 24 or 25 is going to give you much more to deal with on the set than shooting at 29.97/30 or higher. You can always force motion blur in post but you cannot always fix juddering shots.

                      • 8. Re: Can AE smooth out motion jitter in tracking shot.
                        adamneer Level 2

                        Not sure if this will help at all, but perhaps a combination of Twixtor and "rolling shutter repair" could be used, and if you have any black edges to fill, I'd suggest another plugin by Re:Vision called Re:fill, which I use on almost all of my panning stabilization shots that go out of frame momentarily.