现在有些地图有这样的要求，即在一幅地图中，投影中心附近比例尺应较大，边缘部分可以较小，甚至相差几倍，以能详细地显示投影中心附近的地物。为了解决这个问题，曾有人拟定了辐射一变比例尺投影，即自投影中心向四周辐射以显示其变化。本文在说明了辐射一变比例尺投影的基础上，阐明了多焦点投影，其投影中心有若干个，各间其四周辐射，这就能更好地显示各地地物的变化。

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.