Our first generation tracking markers developed at Cinesite were incredibly simple: regular lawn tennis balls that had been painted red. They were fastened at precise 4’ intervals (1.219 m) to the painted green screen wall. On the floor, we used flat vinyl stickers of the same diameter as the tennis balls (6.6 cm) also along the same precise 1.219m grid. The texture of the tennis ball was hard to describe, as it was slightly fuzzy, just like a tennis ball, but had paint particles on it forming tiny blobs and gooey looking sections. The first movie we used them on was “French Kiss” (1995) followed by “Under Siege 2"
The markers having a known position could be used by our matchmoving software (mooVtracker) to calculate camera position based on only four points. To do this, it needed to know the exact positions of the markers, thus the precise grid layout. On most shots, we could calculate the camera at almost 24fps for near-real playback to judge our tracking. You can see the column/row markers (0, 1, 2, 3) in the still you sent me that help identifying which row we were seeing.
I supervised a team of almost 20 matchmovers, none of whom had used the software before, or even done matchmoving, as it was very new.
After Space Jam, I designed a 15cm cross made of 5cm wide blue screen material, and we either used self-adhesive material to stick it to a hard green screen, or we used velcro hooks to stick them to green screen fabric. The 15cm blue screen cross gave us a similar target we could track using our center-of-mass tracking algorithm, and we could often use keying software to remove them from a background without having to paint as much as we would using red markers. We ended up using the cross markers on most other shoots, most notably “Sphere” and “Jerry Maguire." Many people still use blue fabric crosses for tracking markers to this day. :)
The markers having a known position could be used by our matchmoving software (mooVtracker) to calculate camera position based on only four points. To do this, it needed to know the exact positions of the markers, thus the precise grid layout. On most shots, we could calculate the camera at almost 24fps for near-real playback to judge our tracking. You can see the column/row markers (0, 1, 2, 3) in the still you sent me that help identifying which row we were seeing.
I supervised a team of almost 20 matchmovers, none of whom had used the software before, or even done matchmoving, as it was very new.
After Space Jam, I designed a 15cm cross made of 5cm wide blue screen material, and we either used self-adhesive material to stick it to a hard green screen, or we used velcro hooks to stick them to green screen fabric. The 15cm blue screen cross gave us a similar target we could track using our center-of-mass tracking algorithm, and we could often use keying software to remove them from a background without having to paint as much as we would using red markers. We ended up using the cross markers on most other shoots, most notably “Sphere” and “Jerry Maguire." Many people still use blue fabric crosses for tracking markers to this day. :)