关键词: 辐射一变比例尺投影, 多焦点投影, 经验参数, 统计专题地图

Abstract: One of (he current requirements on some maps is that the projection center has a larger scale and the margin has a smaller one. The difference in scale may be as large as several limes, with the aim of achieving more detailed representation of the ground objects which are near the projection center. To solve this problem, some authors worked out radial- changing scale projection, i.e., the scale changes radially from the projection center going all around. This paper gives a description of this projection on this basis, than deals with polyfocal projection in which the scales change radially from respective projection centers, which are mere than one, going all around, thereby leading to a belter represcntetion of the varying details of ground objects according to their distances from the projection centers. The principle and the process of effecting this projection are the same as the redial-changing scale projection.

Key words: Radial-changing scale projection, Polyfocal projection, Experimental pa-rameter, Statistically thematic map