TIEVisionImage.goodFeaturesToTrack

Declaration

function goodFeaturesToTrack(maxCorners: int32_t; qualityLevel: Double; minDistance: Double; mask: TIEVisionImage = nil; blockSize: int32_t = 3; useHarrisDetector: bool32 = False; k: Double = 0.04): TIEVisionVectorPoint2f; safecall;

Description

Detects strong corners using Shi-Tomasi (useHarrisDetector = False, default) or the Harris detector (useHarrisDetector = True).
Returns a TIEVisionVectorPoint2f of corner locations. The image may be 8-bit gray or 8-bit 3/4-channel color (color is converted to gray). 1-bit images are not supported.

Parameter	Description
maxCorners	Maximum number of corners to return. If <= 0 all corners above the quality threshold are returned
qualityLevel	Minimum accepted quality, as a fraction of the best corner (greater than 0 and less than 1, e.g. 0.01)
minDistance	Minimum Euclidean distance between returned corners
mask	Optional 8-bit 1-channel mask the same size as the image. Non-zero pixels are searched
blockSize	Neighborhood size for corner calculation (default 3)
useHarrisDetector	False = Shi-Tomasi (default). True = Harris
k	Harris free parameter (used only when useHarrisDetector is True, default 0.04)

Demo

Demos\ImageEditing\EveryMethod\EveryMethod.dpr

Examples

Also see: Automated Samples

// Find up to 100 Shi-Tomasi corners
pts := ImageEnView1.IEBitmap.GetIEVisionImage().goodFeaturesToTrack( 100, 0.01, 10 );
for i := 0 to pts.size - 1 do
begin
pt := pts.getPoint( i );
ImageEnView1.IEBitmap.Canvas.Ellipse( Round( pt.x ) - 2, Round( pt.y ) - 2, Round( pt.x ) + 2, Round( pt.y ) + 2 );
end;
ImageEnView1.Update();

// Harris corners instead of Shi-Tomasi
pts := ImageEnView1.IEBitmap.GetIEVisionImage().goodFeaturesToTrack( 100, 0.01, 10, nil, 3, True );

// Load test image
ImageEnView1.IO.LoadFromFile( 'D:\TestImage.jpg' );

// Find the strongest corners in the image and mark them with a red circle
pts := ImageEnView1.IEBitmap.GetIEVisionImage().goodFeaturesToTrack( 100, 0.01, 10, nil, 3, False );
ImageEnView1.IEBitmap.IECanvas.Pen.Color   := clRed;
ImageEnView1.IEBitmap.IECanvas.Pen.Width   := 2;
ImageEnView1.IEBitmap.IECanvas.Brush.Style := bsClear;
for i := 0 to pts.size - 1 do
begin
  pt := pts.getPoint( i );
  ImageEnView1.IEBitmap.IECanvas.Ellipse( Round( pt.x ) - 3, Round( pt.y ) - 3, Round( pt.x ) + 3, Round( pt.y ) + 3 );
end;
ImageEnView1.Update();

TIEVisionImage.goodFeaturesToTrack