ufo on earth

R/Greenberg Associates created the film's optical effects, including the alien's ability to become invisible, its thermal vision point-of-view, its glowing blood, and the electrical spark effects.[7] The invisibility effect was achieved by having someone in a bright red suit (because it was the farthest opposite of the green of the jungle and the blue of the sky) the size of the Predator. The red was removed with chroma key techniques, leaving an empty area. The take was then repeated without the actors using a 30% wider lens on the camera. When the two takes were combined optically, the jungle from the second take filled in the empty area. Because the second take was filmed with a wider lens, a vague outline of the alien could be seen with the background scenery bending around its shape.[7] For the thermal vision, infrared film could not be used because it did not register in the range of body temperature wavelengths. The filmmakers used an inframetrics thermal video scanner as it gave good heat images of objects and people.[7] The glowing blood was achieved by green liquid from chem-lite sticks used by campers.[7] The electrical sparks were rotoscoped animation using white paper pin registered on portable light tables to black and white prints of the film frames. The drawings were composited by the optical crew for the finished effects.[7] The film was nominated for an Academy Award for Visual Effects.