ellipses on image

3 ビュー (過去 30 日間)
thoraya 2012 年 6 月 20 日
hi; I have a set of ellipses where each ellipse is defined by its center position (x,y) , an orientaion angle teta, major axe a and a minor axe b. i want to find a way in order to draw those ellipses on a given image* Img* . any idea please? thank you
  1 件のコメント
Image Analyst
Image Analyst 2012 年 7 月 8 日
"Burn" it into the image pixels, or just display above the image in the overlay (without changing image pixel values at all)?


回答 (2 件)

Walter Roberson
Walter Roberson 2012 年 7 月 8 日
One way is to calculate a circle such as is described in the FAQ. Make it a unit circle as you first calculate it. Multiply the x coordinates by (a/2) and the y coordinates by (b/2). Then use hgtransform() to rotate it around the angle. Finally, add the center coordinates to the transformed results.
  4 件のコメント
Walter Roberson
Walter Roberson 2012 年 7 月 9 日
I have no objection to using a rotation matrix instead of hgtransform() :-)


Ryan 2012 年 7 月 9 日
編集済み: Ryan 2012 年 7 月 9 日
Use pdeellip (if you have the PDE toolbox):
(xc,yc) = centroid
(a,b) = semiaxes
phi = rotation of ellipse


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