C.R. Gilman 1973 <p>The U.S. Geological Survey recently undertook the investigation&nbsp;of two seemingly unrelated cartographic tasks: (1) the preparation&nbsp;of map copy for digitizing and (2) the production of experimental&nbsp;slope maps. Both tasks, however, require techniques and&nbsp;equipment for changing or manipulating the line weights of existing&nbsp;map symbols and producing suitable reproduction copy. After a study&nbsp;of existing equipment, a prototype revolving illuminator was designed&nbsp;and fabricated for experiments in line-weight manipulation. Sufficient&nbsp;exposures have been made with the device to indicate that positive&nbsp;control of line-weight increases and decreases up to 0.2 inch is&nbsp;attainable. The device has been used for photomechanical experiments&nbsp;in slope mapping, hill shading, and preparation of map copy for&nbsp;digitizing.</p> application/pdf en U.S. Geological Survey Photomechanical experiments in automated cartography article