How is the swimmer's name and country flag image displayed at the end of each lane in the Olympic swimming events?

Several companies have developed specialized tracking systems for collecting real-time data from different types of sports. These tracking systems are now used by broadcasters to add graphics elements that are "registered" or

"locked on" to the video. An early example is the Sportvision's FoxTrack hockey puck tracking system which allows the broadcaster to render glows or streaks where the hockey puck appears in the video frame.

More recently Sportvision has developed a system for rendering a virtual "1st and 10" line now used in many NFL broadcasts. Another form of registered graphics enhancement, also targeted towards sports broadcasts, is the insertion of images (typically advertising logos) registered to physical surfaces at the event site (e.g., the playing field, existing billboards). Orad and Princeton Video Image are among the pioneers of this technique. As a recent example, in NBC broadcasts from the summer Olympics in Sydney, shots of the swimming events had flags inserted into the swimming lanes to help viewers identify the competitors.

Extremely accurate camera tracking is the basis for inserting registered graphics in live video. Camera tracking equipment is well known from virtual studiOS [7] and special-effects work, however live production with highzoom cameras, as is common for sports, adds to the challenge of collecting accurate camera data.

Comment: good luck finding a detailed explanation on the internet of how it's done exactly. If somebody does, please share. It would be interesting to know.