Create Delta

Used to create a delta TM between a surface and plane or between two surfaces, which can then be used for Isopach contouring.

You can access this tool from the following:

Ribbon: Terrain > Create > Additional Methods split button

The Delta Surface tool creates a delta TM between a surface and plane or between two surfaces, which can then be used for Isopach contouring. The Z value in the delta TM is the difference between the two specified models or model and surface, rather than actual elevations. Any voids in any of the terrain models produces a corresponding void in the delta model (as the software cannot compute the difference in these areas).

Note: It is prudent to use a Feature Definition unique from the original TM, so each can be distinguished, as the delta TM is on top of the original TM when reviewing in a Top View.

Settings	Description
Delta Method	Terrain Model to Terrain Model: specify two files. Terrain Model to Plane: specify one file and an elevation.
Vertical Offset 1	Vertical Offset 1 moves the first terrain model up (positive value) or down (negative value) by the offset distance, in terms of master units prior to processing the delta command.
Vertical Offset 2	Vertical Offset 2 moves the second terrain model up (positive value) or down (negative value) by the offset distance, in terms of master units prior to processing the delta command.
To Plane	elevation of the plane specified in terms of master units (feet or meters).

Workflow

Select the tool.
Set the Feature and Name for the delta Terrain Model.
Follow the heads-up prompts:

Prompt	User Action
Select the Delta Method.	Graphically select the TM.
Locate first terrain model.	Graphically select the TM.
Locate second terrain model or Enter Plane.	Graphically select the TM or enter elevation (in master units).