hough transformation

[bernhard_LA]

bin auf der Suche nach einer korrekten Implementierung der Hough Transformation für Linien in Pascal,
der Code unten liefert nicht den korrekten Accumulator Inhalt zurück

Delphi-Quellcode:

THoughResult = array of array of Integer 


///
///   Hough transformation for line detection
///   r =  sin(theta) * a + cos(theta) * b
///
///
procedure Hough_LineDetection ( AnalysisBitmap : TBitMap; var aHoughResult :  THoughResult  );
var x,y, theta  : integer;
    r           : Extended;
    ImageWidth  : integer;
    ImageHeight : Integer;
    max_d       : Integer;

begin


   ///  size of hough array
   ImageWidth := AnalysisBitmap.Width;
   ImageHeight:= AnalysisBitmap.Height;

   max_d := round( sqrt( ImageHeight* ImageHeight + ImageWidth * ImageWidth   ) ) ;

   SetLength(aHoughResult,360, max_d );

   // For all rows in image do :
   for y:=0 to AnalysisBitmap.Height-1 do
   begin

   // For all pixel in one row do :
   for x:=0 to AnalysisBitmap.Width-1 do
   begin

      // Is there a point there or not ?  If not, just skip the pixel ( threshold based methode ...)
      if IsPixel(x, y, AnalysisBitmap, 128 ) then
      begin
           // iterate the unknown variables :   ( r, theta )
           // loop theta ->  to be able to determine the other unknown -> r
           for theta:=0 to 359 do
           begin
                r:=x*cos(theta*PI/360) + y*sin(theta*PI/360);

                // Plot the finding (theta,r) into an array.
                // Ignore negative values...
                //
                if r>=0 then Inc(aHoughResult[theta,round(r)]);
           end;
      end;
   end;
  end;


end;