旋偏角是航测外方位元素中的一种,在航空摄影中尚难杜绝。随着测图比例尺的增大,旋偏角的超限变得频繁和难以控制。当航摄比例尺大于1/4000时,旋偏角的超限明显增加,几乎占各类比例尺旋偏角作废的80％以上,造成不应有的损失。这是我国在执行国标GB6962-86航空摄影规范时出现的情况,应引起我们的重视。 Declination angle is one of the outer elements of aerial survey, still difficult to eliminate in aerial photography. As the scale of the map increases, the overrun of the declination angle becomes more frequent and difficult to control. When the aerial photograph scale is greater than 1/4000, the overrun of the declination angle obviously increases, accounting for more than 80% of the declination angles of all kinds of scales, causing undue losses. This is our country in the implementation of the national standard GB6962-86 aerial photography when the situation occurs, should arouse our attention.