3VR Security, a San Francisco video surveillance start-up that provides sophisticated ways for companies to track employees and others entering their premises, has raised $15 million more in venture backing.

The deal valued the company significantly higher than previously, in part because the promise of video surveillance has increased, the company said. The company cites industry analysts in saying the market for “video management” will be $7.2 billion by 2008.

Significantly, Palo Alto venture capital firm DAG Ventures led the round, which is the 3VR’s third. It is just the latest example of the firm’s big bets on the video and new media area. DAG is also arriving relatively late and bidding up the value of many of the companies it invests in. DAG has invested in many of these companies only after another venture firm, Kleiner Perkins, has invested. The deals include podcasting company Podshow and social networking company, Friendster.

3VR’s existing investors In-Q-Tel (the venture arm of the CIA), VantagePoint Venture Partners and venture firm Kleiner Perkins, also participated in this latest round.

3VR recently released its “Version 5.0,” which the company said is the industry’s first video surveillance platform to allow face “watch lists,” alerts and searches across multiple video surveillance installations. The 3VR system is being used by major banks, government agencies, hotels and corporations, the company said. The company has previously raised $15 million.