diff --git a/src/grid.py b/src/grid.py
--- a/src/grid.py
+++ b/src/grid.py
@@ -4,7 +4,7 @@ from epoint import EPoint
 
 ## Projective transformation of a point with a matrix A.
 #  
-#  Takes a point as a horizontal vector and multiplies it transposed with A from left.
+#  Takes a point as a horizontal vector, transposes it and multiplies with A from left.
 #  
 #  @return transformed point as a numpy.array
 def transformPoint(point,A):
@@ -21,11 +21,12 @@ class Grid:
 	#
 	#  The result is stored in grid.intersections, a boardSize*boardSize list with [row][column] coordinates.
 	#
-	#  @param corners a properly initialized Corners object. !! Needs a check for the proper initialization.
+	#  @param corners list of EPoints in ABCD order per corners.Corners.canonizeOrder().
+	# !! Needs a check for proper initialization.
 	def __init__(self,corners):
 		# ad
 		# bc
-		a,b,c,d=[c.toProjective() for c in corners.corners]
+		a,b,c,d=[c.toProjective() for c in corners]
 
 		p1=numpy.cross(a,b)
 		p2=numpy.cross(c,d)
@@ -60,12 +61,12 @@ class Grid:
 				affineIntersection=(rowStart*(boardSize-1-c)+rowEnd*c) / (boardSize-1)
 				self.intersections[r][c]=EPoint.fromProjective(transformPoint(affineIntersection.toProjective(),rectiMatrixInv))
 
-	def stoneSizeAt(self,r,c,sizeCoef):
+	def stoneSizeAt(self,r,c):
 		intersection=self.intersections[r][c]
 
-		if c>0: width=sizeCoef*(intersection.x-self.intersections[r][c-1].x)
-		else: width=sizeCoef*(self.intersections[r][c+1].x-intersection.x)
-		if r>0: height=sizeCoef*(intersection.y-self.intersections[r-1][c].y)
-		else: height=sizeCoef*(self.intersections[r+1][c].y-intersection.y)
+		if c>0: width=intersection.x - self.intersections[r][c-1].x
+		else: width=self.intersections[r][c+1].x - intersection.x
+		if r>0: height=intersection.y - self.intersections[r-1][c].y
+		else: height=self.intersections[r+1][c].y - intersection.y
 
 		return (width,height)