TIEVisionMath.getAffineTransform

Declaration

function getAffineTransform(srcPoints: TIEVisionVectorPoint2f; dstPoints: TIEVisionVectorPoint2f): TIEVisionMatrix; safecall;

Description

Calculates the affine transformation (combination of move, scale, rotate and skew) that maps three source points exactly to three destination points.
Returns a 2x3 matrix (64 bit floating point values) for use with warpAffine.
The matrix maps a point (x, y) to:
x' = m[0, 0] * x + m[0, 1] * y + m[0, 2]
y' = m[1, 0] * x + m[1, 1] * y + m[1, 2]
The values can be read with PDoubleArray( M.getScanline( row ))[ col ].

Note: Raises an exception if either list does not contain exactly three points, or the source points are collinear

Demo

Example

// Skew an image so that its top-left, top-right and bottom-left corners move to new positions
w := ImageEnView1.IEBitmap.Width;
h := ImageEnView1.IEBitmap.Height;
srcPoints := IEVisionLib().createVectorPoint2f();
srcPoints.push_back( IEVisionPoint2f( 0, 0 ));
srcPoints.push_back( IEVisionPoint2f( w, 0 ));
srcPoints.push_back( IEVisionPoint2f( 0, h ));
dstPoints := IEVisionLib().createVectorPoint2f();
dstPoints.push_back( IEVisionPoint2f( w * 0.1, h * 0.05 ));
dstPoints.push_back( IEVisionPoint2f( w * 0.9, 0 ));
dstPoints.push_back( IEVisionPoint2f( 0, h * 0.9 ));

M := IEVisionLib().createMath().getAffineTransform( srcPoints, dstPoints );
img := ImageEnView1.IEBitmap.GetIEVisionImage().warpAffine( M, IEVisionSize( w, h ));
ImageEnView1.IEBitmap.AssignIEVisionImage( img );

See Also

◼warpAffine
◼findHomography
◼delaunayTriangulation

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