ON LOCATION Introduction In the Field Back in the Lab What We Can Learn In the Field When deciding how to document these invaluable tracks, a variety of methods are considered. The level of accuracy and detail of resolution must be considered, along with the location, sun angle, accessibility, weather, timeframe and availability of people with the necessary technical skills. For this project, the process begins out in the field (the tracksite or dry wash) among the actual tracks, where the surface is cleared of covering debris. Research teams locate tracks early and late in the day, when long shadows allow easier spotting of the footprints. However, to be able to see the smaller, shallower, and less complete tracks, the limestone surface has to be "crawled" meter by meter. Each track is marked, numbered, and sketched onto a map with a scale of 1 inch = 1 meter. These photographs are used by scientists to develop the plan for the next step in the process – taking photographs of the tracksite from a lower altitude. Left: Neffra and a team of surveyors, photographers, and scientists begin by laying out the area into one-meter sections. They measure and take close-up, high-resolution pictures of each section, documenting the location and describing each track. This method provides the most detailed pictures of each individual track. Above: High-altitude aerial photographs are then taken of the whole area by an aircraft flying above the site. These images collect an unbiased record of what is actually on the ground. Cameras that take very large photographs are mounted in the bottom of commercial aircraft. These photos taken from the air are called aerial photographs. Since Federal Aviation Administration (FAA) regulations prohibit aircraft from flying low enough to the ground to take photographs that show the details of a trackway (several tracks made by the same individual), another method is used for getting a closer look. This is done with an Aerial Camera Blimp System (a blimp is a type of air balloon). The blimp is filled with about 450 cubic feet of helium. It is normally kept inflated and driven to the site in an enclosed trailer. The area where the tracks were found is nicknamed the "ballroom." Images of the track surface taken from the blimp provide paleontologists with a visual record of the location of the tracks, as well as the relationship of the tracks to one another. The blimp is designed to be controlled with a tether/control cable by a single operator, but it can often get quite windy, so a second line helps control it. The camera is set on auto exposure and the focus is preset. Since the blimp moves in the breeze, fast shutter speeds are needed. A 35-mm medium-format camera is mounted on a pan and tilt motor to the 20-foot-long, helium-filled blimp. A small (1 oz.) video camera is mounted on the still camera, which is controlled and viewed from the ground. The blimp rises up to 250 feet above the ground to take a series of systematic, low-altitude, stereo (three-dimensional) pictures. As the video camera scans the area, the ground team selects the exact views they want the still camera to take. The pan-and-tilt camera mount is controlled electronically by the operator on the ground, allowing the pictures of specific features to be taken. Out in the field, Neffra holds the blimp in place while the Aerial Camera Blimp System pilot changes the film. Neffra enjoys being out in the field. Here, she carries the camera and tripod to the tracksite. The close-range images taken from the blimp clearly show the tracks found at the Red Gulch Dinosaur Tracksite. NEXT: Back in the Lab