Protec Projection Maps on Moving Surfaces

By Matthew Brennesholtz
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Object tracking technology supplied by CAST BlackTrax Ltd (Toronto, Canada) was used by Production Technology LLC (Protec, Dubai, U.A.E.), at the Hamdan bin Mohammed Programme for Smart Government awards (HbMPSG) in late 2014. Protec is said to be the largest live events production and equipment rental company in the Middle East and the fifth largest of this type of company in the world.

Example BlackTrax System tracking an actor

BlackTrax is a system where live event producers can track an object in real time. Systems are available that track in three dimensions (x-y-z) or six dimensions (x-y-z and roll-pitch-yaw). At live events, these sensors are used to track moving objects, including actors and other people on stage. This motion tracking information is then used for a variety of applications by the company running the event.

One main application involves tracking people and using this information to control robotically operated follow spots and cameras. This can significantly reduce production costs in two ways. First, robotically controlled spots and cameras do not require a human operator to track the actor or MC on stage. Second, the set up and rehearsal time can be greatly reduced, since actors and others do not need to learn 3D checkpoints as precisely. This can be especially important for road shows where every venue is different and checkpoints for robotic cameras and lights would be different.

BlackTrax includes includes both IR beacon and a Bluetooth transmitter, attached to the person or object to be tracked. The BTBeacon includes accelerometers and gyroscopes for orientation.

Fixed BTSensors pick up the beacon signal which are decoded into position information by the BTController. A BTServer can control multiple sensor systems and pass on the position information to the target systems that need to have this position information. These systems can include automated lighting, 3D/Spatial audio systems, video servers and robotic cameras.

At the HbMPSG event, Protec used the BlackTrax system to track three objects in a projection mapping application. Since the objects used as targets for the projections were moving, the video server controlling the 20 Christie projectors used needed to know the position of the target screens at all times. There were three objects tracked – a large suspended cube that could rotate and tile and two pieces of a jigsaw puzzle that could come together and move apart.

“We chose BlackTrax specifically for this project, because we knew it was the only solution that would work”, said Lighting Designer, Aaron Russ at Protec. “We needed to track each surface of the cube and jigsaw so we could project on all surfaces as they moved during the show. To do this, we added four BlackTrax beacons into the cube, each with two stringers for a total of eight tracking points. We placed one tracking point on each corner, so that we had complete coverage of all sides of the cube. We then placed the BlackTrax Beacons at the top of the cube for easy access, and ran stringer extensions down to connect the tracking points to the beacon. For the jigsaw pieces we used three beacons in each piece. The BlackTrax cameras were hung on an angle so that they could see over the jigsaw pieces and be able to track all eight corners of the cube”.

BlackTrax from VideoThe Cube and the two pieces of the Jigsaw at the HbMPSG eventThe Cube and the two pieces of the Jigsaw at the HbMPSG even BlackTrax streamed realtime positional information via high-speed protocol (RTTrPM) to the d3 media server. d3 was able to construct a rigid body cube (virtual version of the cube) in its media server design tool that behaved and moved like the real cube, in realtime by using the positional information received from BlackTrax.

“We used the d3 media server to create a virtual representation of the stage set including the cube and jigsaw. Even if 5 tracking points were obscured, we could still rely on only 3 tracking points and still be able to track the entire cube. This was because the clever d3 system understood the object as whole, instead of six individual screens”, added Aaron.

The content for the awards ceremony was created using live camera feeds of award winners, audience members and custom created graphics and videos. Protec not only supplied BlackTrax and d3, the company also supplied 32 x Christie HD20K J Series projectors to create the spectacular visuals along with the complete audio, lighting and rigging solution.

“Set up and integration with the video servers was really easy. Everyone was very impressed with what BlackTrax did. d3 and BlackTrax experts were on hand to help with set up. They were great guys and knew their products. We’d happily have then back over again for future projects”. BlackTrax has posted a YouTube video that includes both the set-up and alignment of the system plus scenes from the HbMPSG event. – Matthew Brennesholtz