At present, the main ways to obtain DEM are: ground measurements method, the paper map digitization method, space-sensors based methods and digital photographic methods.

目前获取DEM的主要方式有：地面测量方法、现有地图数字化法、基于空间传感器法及数字摄影测量法。

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The effect of aerial photographic swing angle to the orientation precision of digital photogrammetry changes with the processing technical methods and the size of map scale.

航摄旋偏角对测图定向精度的影响随着处理技术手段的变换而改变，也随着比例尺由小变大而改变。

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