Draped to Level

Use the Draped to Level function to upward continue a potential field anomaly grid measured on a "draped surface" defined by an elevation grid (e.g., gravity data measured on the topographic surface or a draped aeromag survey) to a constant elevation (flat) elevation. All input grids must be coincident (i.e., dimensions, cell size, and locations must match) for Draped to Level Upward Continuation to work correctly.

This dialog 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.

To Perform a Draped to Level Upward Transformation

1. On the GM-SYS 3D Tools menu, select Upward Continuation and then select Draped to Level.
   The Upward Continue - Draped to Level dialog appears.

2. From the dropdown list, select the Input Anomaly Grid (draped). This is an input variable-level (draped) gravity or magnetic grid. Alternately, you can browse to the grid.

3. From the dropdown list, select the Observation Elevation Grid. This is the elevation grid where anomaly data were measured relative to sea level (+ up). Elevations must be in same units as grid horizontal units. Alternately, you can browse to the grid.

4. Browse to the Output Anomaly Grid (level). This is an upward-continued anomaly grid at target draped elevation.

5. Specify the Target Elevation. This is a new constant elevation for observed data relative to sea level (+ up). Must be greater than the maximum of the Observed Elevation Grid.

6. Specify the Number of Levels (<100). This is the number of intermediate levels used in upward continuation process. Max is 100; min is 2. The default is 10.

7. Click OK. The new grid appears.