Roller-Type Electronic Digital Planimeters made by Placom. Placom Planimeters are area measuring tools used by land surveyors, golf course designers, engineers, and any one wanting to measure the area of an irregular shape. Simply enter your drawings scale, then start rolling the planimeter measuring in a clockwise motion, close the loop and the planimeter will give you the area inside of the closed loop measured. If you're looking for an area measuring tool, then a planimeter is what you want.