Los Angeles-based RealD, a developer of 3D movie projection technology, said last night that the firm's 3D technology was behind over 50 percent of the weekend domestic gross on Twentieth Century Fox's AVATAR film. The firm said its screens brought in nearly $40M of the total domestic box office from the James Cameron film. RealD develops 3D projection technology for digital theaters. AVATAR had a $242.5M opening weekend.