Now that the 52nd Super Bowl is right around the corner, February 4th 2018, the NFL will be using all the special effects in their tool shed. One of the amazing mysteries in video is the Yellow 1st and Ten line. Since we are a professional video production company, we get asked, “How do they do that”. Well, it’s complicated as you can imagine.
So lets start with a little background.
Before 1998, Football viewers had to estimate where the first-down was on the field. Like the picture below, the 1st down markerts were on the side of the field and were often blocked from view by players, coaches, and refs. They were hard to see on television.
The 1st and Ten graphics first debuted in a televised game between the Bengals and the Ravens. Sportvision introduced a computer generated yellow line across the entire football field to show viewers exactly where the offensive team must carry the ball in order to get a first down.
Like all Technology, the 1st and Ten line has evolved over time.
THIS IS HOW IT WORKS:
The field is created on a computer in 3D space. Although all football fields must meet exact size requirements every field is quite different when it comes to this precise effect, so each field must be built in 3D space. The NFL has 32 teams and is growing internationally. A 3D model allows for precise perspective viewing at all angles. The average margin of error on the 1st and Ten line is just 1.3 inches.
Since the cameras move in relation to the action on the field, an encoding system in each camera relays precise camera position in relation to the 3D model of the football field. This includes lens focal length, f-stop, height, angle, and geo position. Since the 3D model can be viewed at all perspectives the camera tells the computer where it is in relationship to the field and the computer perfectly aligns the model with the field in each camera’s view. The 1st and Ten line is generated in the 3D model and only the line becomes visible while the rest of the model remains perfectly transparent. To accurately place the line the operator simply selects the position of the ball placed by the ref with just a mouse click and automatically the computer reveals the line at exactly the correct distance to reach a 1st down. This occurs for each camera perspective.
How Do they put the line only over the field and nothing else?
A color palette is created with all the hues of the grass and field. This is many shades of green and possibly brown. Every pixel in the display is analyzed in real time and only the pixels that match this color palette get replaced with the line. This is called keying or chroma keying. There are several teams and fields that challenge this effect because of conflicting colors between uniforms and the color palette of the field. Weather and lighting also make this challenging.
Wait there’s more!
Mark Shattuck, EIC (engineer in charge) for Clark Media of Provo Utah has worked with another system called TrackVision by ORAD. This system does not use encoders or any hardware at the camera. You simply aim the cameras at multiple sections of the field (with the field lines in view) and make freeze frame still images. The computer then creates the 3D environment from these freeze frames.
Now this is high powered processing in a live event. It takes 4 operators, a spotter and field-operator who work together to put the yard lines into the system and two others for live adjustments. The operator is in a huge truck full of equipment including eight high powered computers, three of which are used only with the video cameras. The spotter is located in the press box with the announcers. The delay to accomplish the 1st and Ten line is 2/3 of a second, so they have to work quick. With a cost of around $35,000 per game, the 1st and Ten technology has improved the mangagement of the game by coaches and officials while greatly enhancing the viewing experience.