Level to Draped Upward Continuation (GMS3VUPD GX)

The Level to Draped function (GM-SYS 3D Tools > Upward Continuation menu) continues a potential field anomaly grid measured at a constant elevation to a variable surface defined by an elevation grid.

This GX may only be used for upward continuation. It will terminate with an error if any part of the original elevation grid is above the new constant elevation.

Upward Continue - Level to Draped dialog options

Input anomaly grid (level)	Single level gravity or magnetic grid.
Observation elevation	Original observation elevation.
Output anomaly grid (draped)	Upward-continued grid at new variable elevation.
Target elevation Grid	New constant elevation for observed data relative to sea level (+ up). Must be greater than the maximum of the Observed Elevation Grid.
Number of levels	Number of intermediate levels used in upward continuation process. Max is 100; min is 2.

Application Notes

All input grids must be coincident (i.e., dimensions, cell size, and locations must match) for Draped to Level Upward Continuation to work correctly. Draped to Level Upward Continuation uses the "chessboard" method described by Cordell (1985)¹. The chessboard method interpolates between a number of intermediate parallel surfaces in order to estimate variable surface-to-level continuation. The intermediate parallel surfaces are computed using the standard MAGMAP upward continuation filter.

Level to Draped Upward Continuation is actually a wrapper that does a little grid math and calls the Draped to Level Upward Continuation.

Reference

[1] Cordell, Lindrith, 1985, "Techniques, applications, and problems of analytical continuation of New Mexico aeromagnetic data between arbitrary surfaces of very high relief [abs.]", Proceedings of the International Meeting on Potential Fields in Rugged Topography, Institute of Geophysics, University of Lausanne, Switzerland, Bulletin No. 7, pp. 96-99.