A.水平網(wǎng)B.絕對網(wǎng)C.豎直網(wǎng)D.傾斜網(wǎng)
A.求得變形點(diǎn)的絕對變形值B.提高監(jiān)測精度C.提高監(jiān)測效率D.求得變形點(diǎn)的相對變形值
A.北京54B.WGS-84C.1980西安D.2000國家大地