DME Component Libraries for .NET 2023 r2

## TerrainProviderGetHessian Method |

Get the interpolated hessian matrix based on the function of height with respect to the specified longitude and latitude relative to the provider's Shape. This method produces a matrix representing the mixed second order partial derivatives of height in the ShapeFixedFrame.

Note: The direction for the gradient and hessian is defined for use with the directional derivative on the surface. The gradient is defined to be orthogonal to the terrain surface with its surface projection in the direction of the greatest increase in the height. To obtain the second directional derivative for the height (acceleration of height along a particular azimuth), take the negative of the hessian then pre and post multiply it by the velocity vector along the desired azimuth. Then add the negative gradient dotted with the derivative of the velocity vector along the surface.

Syntax

- longitude
- Type: SystemDouble

The longitude, in radians. Requesting a gradient for a longitude less than -π or greater than π will always return NaN. - latitude
- Type: SystemDouble

The latitude, in radians. Requesting a gradient for a latitude less than -π/2 or greater than π/2 will always return NaN.

The hessian matrix expressed in the ShapeFixedFrame at the given location, in meters of height per meters of surface distance squared.

See Also