CogTransform2DLinear MapArea Method Cognex VisionPro 9.10
Maps the given area through this transform and returns the result.

Namespace: Cognex.VisionPro
Assembly: Cognex.VisionPro.Core (in Cognex.VisionPro.Core.dll) Version: 79.0.0.0
Syntax

public double MapArea(
	double area
)

Return Value

Type: Double

The mapped area.

Remarks

Maps the given area through this transformation. MapArea(Double) computes the mapped area by first calculating the area of a unit square and then multiplying the given area by the result.

The area formed by two vectors is the cross product of the vectors. MapArea(Double) takes the vectors (1, 0) and (0, 1), maps these to the new coordinates, and then calculates the cross product. Given the following 2x2 matrix

vector (1, 0) maps to (a, c) and vector (0,1) maps to (b, d). You calculate the cross product as:

The cross product is also equivalent to the determinant.

You may want to call MapArea(Double) with an area of 1.0 to get a conversion constant, and then use this constant in calculations. This saves the overhead of invoking MapArea(Double) multiple times.

See Also