A method with acts for representing a buffer about a feature represented on an ellipsoid or round-object model. The method includes accessing a definition of a buffer stored on one or more computer readable medium in a format readable by a computer application. The definition of the buffer includes a number of arcs around a feature on an ellipsoid or round-object model. Each of the arcs is defined using three points defined using geodetic coordinates. The three points includes two endpoints of a given arc and a point on the arc between the two endpoints. The method further includes rendering the buffer by rendering the plurality of arcs. The method further includes displaying the rendered buffer to a user at a computing system display.