WMS:Transform TINs

The Vertices | Transform command is used to move TIN vertices according to a specified transformation. It is similar to coordinate conversion, but should not be used in place of it. Rather it is most useful if the user needs to transform a set of vertices that were not originally defined in a standard coordinate system so that they align with a standard coordinate system.

When this command is executed, the Transform dialog opens, in which the transformation type and appropriate parameters can be entered. The following transformation types are available:

Scale

Scaling factors for the x, y, and/or z directions are entered. To prevent scaling a specific direction, the default value of 1.0 should be used.

Translate

Translation values for the x, y, and/or z directions are entered. To prevent translation in a specific direction, the default value of 0.0 should be used.

Datum Conversion

Datum conversion can be thought of as converting depths to elevations or elevations to depths. A constant water surface elevation (WSE) value is defined for the conversion process. Note that this is different than simply translating or scaling the z-coordinate. This transformation is governed by the following simple equation:

$newz=WSE-oldz$

Rotate

When rotation is selected, the set of options on the right side of the dialog become available to define the center of rotation. If the Specified Point option is used, then the x- and y- coordinates of the center of rotation needs to be entered. Otherwise, click in the graphics window at the Point or on the Node about which the rotation should occur (this is done after clicking the OK button from the Nodes Transform dialog). The rotation is computed counter-clockwise by the angle around the center of rotation.

Related Topics

• Coordinate Conversions