I’ve been using after effects for a long time, and just recently upgraded to 7.0 Pro. Now that I have the power of the professional version, a client has asked me to do a project involving some motion tracking.
The idea is this: they are selling a new model of skates that they want to promote. In the video, they want me to motion track the kids’ skates and use that information to create some graphics that appear to be caused by the skates (almost as though the skates are leaving a trail.). I have done some trial runs myself to see if I could get it to work… Here’s what I have tried… Laugh at the ghetto nature of it: I attached some neon-orange spheres to the heal of the skates. I then had the talent skate in a way that will be similar to how the project is going to be done. I shot it with my XL2 in 24p.
When I try to track it in AE 7.0, the motion tracker follows it for a fraction of a second, then loses its “hold” on the orange spheres and begins to track a point on the ground. I am using the track motion with the “transform” option. Is my error in my tracking method in AE or in the way it was shot? Is there a better way to provide information (when shooting) that AE can track easier?
I can’t see the footage so I can’t really say if I think it is trackable, but is the orange spheres have a lot of contrast with the background I’de say it probably is trackable. I may be stating the obvious, but be sure to go into the options dialog box of the tracker controls pallete and be sure to change the settings there to “track using RGB.” Im thinking theat with white ice and a light orange ball, this would work well. However, if the ball is signifigantly darker or lighter than the surrounding area you might want to use luminance based tracking. Also, sometimes if found that using a levels filter on source footage to boost the contrast between the tracjed object and the background can help make tracking easier.
If your talent is just moving away from the camera in a linear fashion, there may not be enough difference between frames to keep the tracker “alert”. If you’re filming sideways, motion blur may be the killing factor. Assuming you have enough contrast, you should try to isolate the spheres first. Create an extra comp, treat you footage with some effects (Levels, Threshold) until only the spheres stand out and then render this. Re-import and track your tweaked footage, then simply, if successful, copy the resulting keyframes wherever you need them. Other than that, keep Colin’s tips at the back of your head. Out of curiosity – “Sib Ntsib Dua” – what does it mean and what ethnic origins does it have? Sounds very African too me…
Thanks for the advice. I’ll try those things out. And yes, “Sib ntsib dua” is Hmong in origin, and it is a way of saying “good bye” or “farewell.” Phoenetically, and altogether, it would sound like “shin gee doa.” (excluding the usage of the tones, which are designated by the last letter of each word, except the ‘a’ on dua… not that you REALLY care.) Xeeb is pronounced “Seng,” it is my Homng name.