4 Replies Latest reply on Jul 24, 2014 10:13 AM by Zogeta

    Trouble parenting Trapcode Particular to 2D track

    Zogeta Level 1

      So I'm animating a smoke trail in the sky using Particular.  It's a handheld shot that I've already tracked and applied to a null.  I have some other 3D elements in the sky, so I've tracked the footage and applied the information to a 2D null.

       

       

      My smoke trail is coming from a light emitter in 3D space, which I've animated streaking across the sky.  The emitter is parented to the 2D null.  So now when my frame moves, the emitter moves with it.  But the particles in the smoke trail don't follow the null object's motion, so as my frame moves they float there in their own space.  I tried parenting the 3D camera to the null, but the smoke trail still isn't tracking with my null.  Does anyone have any suggestions for this kind of track?  It's worth noting that I'm NOT parenting the layer with Particular applied to it to anything, nor is it a 3D layer.  My camera is in a nonstandard position and point of view to look at my 3D objects in the sky from a low angle.

        • 1. Re: Trouble parenting Trapcode Particular to 2D track
          Mylenium Most Valuable Participant

          Complete nonsense. Use a light emitter.

           

          Mylenium

          • 2. Re: Re: Trouble parenting Trapcode Particular to 2D track
            Rick Gerard Adobe Community Professional & MVP

            If you are trying to use the motion track applied to the null to move the Emitter (light) then you have two problems. First, you should not try and tie a 3D layer or position to a 2D layer. IOW, your null must be 3D even if your tracking data is 2D.

             

            Second, when you parent the light to the null some interesting things happen. First, the light is not going to end up at the same position as the null unless you move the light to the position of the null to start with. If you don't do that, then parenting will just move the light relative to the null but they will not be in the same position. If it were me I would just use a simple expression to tie the position of the light to the null. Reveal the null's spoliation property, then Alt/Option click on the stopwatch for the Light's position and drag the expression pickwhip to the null's position property. You'll get an expression that looks like this:

            thisComp.layer("Null 1").transform.position

            Second problem I see is in your question. I'm not sure what you mean when you say the particles hang there in their own space. If you want the particles to create a smoke trail then you need to adjust the physics factors so that the particles react like smoke. Here's a sample project where I just used the Smoke preset for Particular, changed the emitter to a light, and then used the expression shown above to tie the light (Emitter) to the animated null.

            Screen Shot 2014-07-15 at 6.32.57 AM.png

            • 3. Re: Trouble parenting Trapcode Particular to 2D track
              Zogeta Level 1

              I did.  The light emitter was then parented to a null.  But no worries, I figured out how to keep the trail of particles in track with the rest of the comp.

              • 4. Re: Re: Trouble parenting Trapcode Particular to 2D track
                Zogeta Level 1

                Thanks.  What I meant is that the trail of particles didn't motion track with the rest of the comp, though the emitter did.  So if the camera would pan a bit the trail wouldn't, though the emitting point and particles born during the pan would, if that makes sense.

                 

                I ended up figuring out the problem by making my 2D null into a 3D layer and inverting it on the x and 7 axis.  Then by parenting my camera to it I had everything tracked in properly.