 Among the other effects ILM had to produce were the transporter beam and the warp speed effect. Mullen noted that the effects'look changed depending on who was directing the film; "everyone wants something distinctive, but nobody wants to get far enough away from the TV series to startle the Trekkies." The effect was produced by cutting out or rotomatting the individual to be transported, then making a vertical slot through which a high-intensity light was positioned. A computer-controlled move would cause the light to spread from the center and fade away, then reset its position and repeat the movement on the opposite side. Handmade acetate filters and gels were applied to give the transporter beam color and patterns, followed by small flickering animated highlights called "bugs" which appeared after the character had dematerialized. The Klingons' transporters were given a harsh red look to differentiate them from the smooth blue Federation effect. Whereas many of the multicolored rainbow warp trail shots from The Wrath of Khan were stock footage taken from the first film, the producers of the third film wanted something new. A streak effect, in which a beauty pass of the ship was combined with blurred passes for each light intensity, was tried first. The result was disappointing; as the Enterprise grew larger the streaks became distorted and out of place. Mullen rejected a straight animation of the warp drive as too bouncy, but the footage was cut in for editing while ILM went through six more approaches to the problem. The final effect, a "vaporous, colorful trail", came together only weeks before the film's release.
