9 Replies Latest reply on Aug 19, 2014 5:57 AM by twetzel2k

    Judder Effect from 3D Camera Renders

    twetzel2k

      I have a 10 second camera pan (90 degree rotation) of a room.  It has been rendered out from 3ds max.  Each image looks great.  When I put it together in AfterEffects, and render it out, I am getting a Judder effect (a vibration as I go across the pan).

       

      How can I get this to stop.  I need a smooth pan.

       

      thank you.

        • 2. Re: Judder Effect from 3D Camera Renders
          Rick Gerard Adobe Community Professional & MVP

          Stroboscopic motion artifacts are more pronounced at lower frame rates. Try your project at 29.97fps instead of 24. Use CC force motion blur to hide the problem. Todd pointed you to my article that goes into depth on the subject. Animation is just like camera work, you have to design your shot around the limitations of the medium. I've never seen a western where the stage coach wheels didn't move backwards in some of the shots.

          • 3. Re: Judder Effect from 3D Camera Renders
            twetzel2k Level 1

            I have rendered out 29.97 and it still does it.    Will try the CC force motion blur.

            • 4. Re: Judder Effect from 3D Camera Renders
              Rick Gerard Adobe Community Professional & MVP

              You may need to change the timing of the move by adjusting the frame rate of the imported image sequence. Forcing motion blur will just hide the problem. Rendering at 29.97 without changing the frame rate of the comp and the frame rate of the image sequence does not change any of the Judder problems. It may make them worse because of blended or duplicated frames.

               

              Also, are you rendering to a delivery format that will playback smoothly. Sometimes Judder is mistakenly diagnosed when the problem is an uncompressed file that will not playback in a media player without dropping frames.

              • 5. Re: Judder Effect from 3D Camera Renders
                twetzel2k Level 1

                Yeah, I tried different codecs and players.   My client needs WMV, so have been using that.   I did a short test of rendering out my animation 60 frames per second and that seems to solve it.  Just means a lot of rendering time.   

                 

                For the imported frame rate method would you go higher? say 40 fps and then use the motion blur?

                • 6. Re: Judder Effect from 3D Camera Renders
                  twetzel2k Level 1

                  so slowing it way down works, but it is too slow for the client.  The motion has to be a set foot/sec speed.

                  I currently have a 10 second pan (90 degrees), 29.97 frame rate input and output,

                   

                  - I tried the cc force motion blur it did not help... I may not be using it correctly, so perhaps need a bit more detail.

                  - I tried some scene motion blur and it looked pretty terrible as well. 

                   

                  The article above mentions:

                  • Fine detail must move at an even number of pixels per frame to avoid the sub pixel problem.

                   

                  How do I set my motion to do that in a 3d program?

                   

                  Thanks for helping and being patient with me.  This is the first time I have encountered this issue.

                  • 7. Re: Judder Effect from 3D Camera Renders
                    twetzel2k Level 1

                    Just to update what else I have tried....

                    rendered out 60 frames per second from 3d software.

                    Imported into AE as 60 frames

                    Used media encoder to render to WMV 29.97 fps.  progressive.  High quality.  Still getting the problem.

                     

                    also added cc force motion blur and still had problem.

                     

                    Not sure what else I can try.

                    • 8. Re: Judder Effect from 3D Camera Renders
                      Rick Gerard Adobe Community Professional & MVP

                      It important to understand that the Judder is caused by the timing of the movement in conjunction with the refresh rate of your display and the frame rate of the video. If your shot is juddering at the standard playback frame rate of your deliverable the only option you have is to change the timing of the move.

                      Here is the approach that I would take.

                      1. Start a new AE project and import your original image sequence
                      2. Select the image sequence in the Project panel and go to File>Interpret Footage> and check the frame rate (the default is 30 fps, I set my default to 29.97 in preferences because that is what I normally use)
                      3. Set the frame rate to match the frame rate of your desired final render
                      4. With the image sequence selected in the Project panel go to File>New Comp From Selection (or right click and select New Comp From selection, or drag to the new comp icon)
                      5. Set composition window resolution to Auto and zoom factor to 50% and do a ram preview to check for Judder (Verify the playback frame rate in the info panel)
                      6. If you do not observe Judder then render a full resolution test using the Adobe Media Encoder and the YouTube or Vimeo Preset that matches your comp's frame rate and check the test for Judder
                      7. If the test render exhibits juddering then return to ae and go to Step 10
                      8. If you observe judder in the RAM preview then step through the comp one frame at a time using the page down key to check for duplicate frames or inconsistent motion especially at the horizontal or vertical edges of the objects in the shot (Be sure to flush your cache and purge everything before doing this step)
                      9. If the motion between is not consistent and predictable then solve that problem by redoing your image sequence
                      10. If the motion in the frame is consistent then Enable Time Remapping on the layer and change the position of the last keyframe by moving it to the left or right about 10% of the timeline
                      11. Enable Frame Blending
                      12. Step through the image sequence a frame at a time to check the look of the frames
                      13. Try a RAM Preview at 50% Zoom factor
                      14. If everything looks good render another test using the AME
                      15. If the Test is OK, you're done. If not, make further adjustments in the timing and try again.

                      If the timing of the shot cannot be changed then do something with the design to change the relative movement between frames. Make the layer 3D, auto orient to the camera, add a camera and do a camera move on the shot. Animate the position of the shot in the frame. Change the scale of the shot comp. Anything that changes the position of the edges of horizontal or vertical detail between frames will eliminate judder. You can mask Judder by using motion blur, but this bandaid is usually not very effective.

                       

                      I hope this helps. If your shot is right on the 'critical pan speed' then you have no choice but to change the timing.

                      • 9. Re: Judder Effect from 3D Camera Renders
                        twetzel2k Level 1

                        This helped...some.  It is probably the best I am going to get.  Thank you very much for the detailed explanation.  I will combine that as well as some other things I have tried as well.

                         

                        Thanks again.