Both geographic and projected coordinate systems include a definition of the assumed shape of the earth (a flattened sphere); this is called the geodetic datum.
地理和投影坐标系都包含对地球形状的假设(一个略扁的球体)；这称为大地基准点。
Through studying the relationship between space vectors of different coordinate systems, a new model of three-dimensional datum transformation is proposed.
从空间几何角度出发，利用空间向量的关系研究坐标转换，提出一种新的三维基准转换模型。
Through studying the relationship between space vectors of different coordinate systems, a new model of three-dimensional datum transformation is proposed.
从空间几何角度出发，利用空间向量的关系研究坐标转换，提出一种新的三维基准转换模型。
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