In one aspect, a method of determining lateral edges of an asphalt mat deposited by a paving machine includes obtaining thermal image data of the asphalt mat at a thermal measuring device associated with the paving machine, and determining, on the paving machine, the lateral edges of the asphalt mat based on a threshold temperature value and the thermal image data. Other aspects include a method of generating a thermal map of an asphalt mat formed by paving machine, and a system for determining lateral edges of an asphalt mat deposited by a paving machine.