in order to generate a mark, an image must first be made. members of onsight-cartograffiti survey a given landscape. from the initial survey locations are chosen based on cultural levels of abstraction; traffic patterns, street cameras, and population densities become defining parameters. images are collected from the location and plotted using GPS. the shapes are then generated, using the perceptual data embedded within the image and the GPS field data recorded from the site. the resulting shape is a combination of these two data fields and it is shown in plan view. objects that obstruct the view affect the shape, as does perspective, location, and space.