The first step of the migration is performed within the perpendicular plane, and the second step of migration is the spatial migration of the side waves.

第一步偏移的实质是在铅垂平面内完成偏移归位，第二步偏移是在空间内完成侧面波的空间归位。

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The theoretical part of the seminar on the measurement technology including the principle of a measurement survey, a plane-table method, a perpendicular survey, a traverse survey, a GPS survey, and using a total station will be conducted at the premises of the Institute of Fine Arts.

UNESCO: 7-8 November 2012, Tashkent, Uzbekistan

This is a special type of Earth model which traces its idealised "horizontal" surface - the plane on which, at any point, the pull of gravity is perpendicular to it.

BBC: Europe's Goce satellite probes Earth's gravity