4 Replies Latest reply on Mar 31, 2011 2:50 PM by Lewiz

    Standard motion blur on 3d camera uses premature frame samples

    Lewiz Level 1

      Hi there everyone, I was wondering if anyone has ever noticed the following issue:

      I have created a couple of 3D layers in AE "space", having a camera zip panning and tilting from one to the other. We're talking like 15 frames rotation moves, so worth a little blurring. Now AE creates a very nice motion blur on those zippy camera moves, be it that half of the sixteen samples needed to calculate the motion blur are taken from the frames yet to come (?????) So, especially in a 'banking' kind of rotation, causing an over time calculated spin blur, the blur itself pops in even before the camera has moved (it's like five frames 'ahead').

       

      Does anyone of you have a similar experience? Is there a workaround without having to create every blur manually?

       

      Oh, by the way, CC Force Time blur crashes on this because it does not like certain effects I used, like Text Anarchy and a couple of standard AE effects (??)

       

      Please help me out on this one. It's easy to recreate this issue: create a new comp, throw in a camera and a video layer and have this video layer rotating round its Z-axis once in a five frames duration, in linear interpolation. Now switch on motion blur for this layer and the timeline. You will notice the blur appears before the video layer has started rotating and when the rotation has stopped, the motion blur is long gone. Appreciate any help, thx.

        • 1. Re: Standard motion blur on 3d camera uses premature frame samples
          Mylenium Most Valuable Participant

          Nothing wrong here, your shutter phase is simply offset. Check your composition settings, Advanced tab.

           

          Mylenium

          1 person found this helpful
          • 2. Re: Standard motion blur on 3d camera uses premature frame samples
            Lewiz Level 1

            Hi Mylenium and thanks for taking the time. I appreciate it a lot, certainly when a known AE guru like you picks up a question like this one.

             

            Unfortunately, though I have tried every offset in steps of 90 degrees up to 720, but the problems persists. Maybe a bigger offset helps? Or a negative one (if possible, haven't tried yet...)

            I don't think this would be of any importance, but the layers I use are mainly AE generated text layers.... but now that I think of it, the entire camera move was imported from Cinema 4D, so every timeline frame is a lineair camera keyframe as well... 546 frames, and thus 546 keyframes for the poor 3D cam... could that be messing up the motion blur calculation.....?

             

            I guess I will try that right after dinner. Thanks again so far, I feel honoured.

            • 3. Re: Standard motion blur on 3d camera uses premature frame samples
              Dave LaRonde Level 6

              You can also use the keyframe assistant to convert beginning and ending keyframes to Easy Out and Easy In keyframes.  I use it all the time, and it helps a lot. 

               

              If you want the motion to hold still until it encounters another keyframe, highlight the ending keyframe and use the Toggle Hold Keyframe command, and AE makes a combination Easy Ease In/Hold keyframe.  Without it, the motion won't hold still until the next keyframe; it will drift.

              1 person found this helpful
              • 4. Re: Standard motion blur on 3d camera uses premature frame samples
                Lewiz Level 1

                Thanks Dave, that is surely a nice way to handle the drifting. I know, sometimes the drifting can be quite organic and so, but in many cases it's not really what you want.

                 

                In this case though, I cannot rebuild the camera move by using a few smartly interpolated keyframes, because it has to match a camera move created in a 3D-program, this multitude of frames I mentioned originates from a .AEC file, an exported camera data file. I need the AE camera to stick exactly to this data... but I will test first thing in the morning whether the replacing of the externally generated frames would be a workaround. In that case, I could adapt my workflow a little and still obtain the desired effect.

                 

                Anyway, thanks for your help, you people help the world keep going round and I appreciate it a lot !