/// <summary>
/// Takes a circle in image space and returns a cooresponding ellipse in image space.
/// This is an ill posed problem. The center is respected but the radius could be taken
/// anywhere around the circle in image space, and that yields different radii in world space.
/// We use the point along the X axis as the radius.
/// </summary>
public Ellipse GetEllipseFromCircle(PointF center, float radius, out PointF radiusLeftInImage, out PointF radiusRightInImage)
{
radiusLeftInImage = new PointF(center.X - radius, center.Y);
radiusRightInImage = new PointF(center.X + radius, center.Y);
if (calibratorType == CalibratorType.Line)
{
return(new Ellipse(center, radius, radius, 0));
}
// Rebuild the world-space circle based on center and radius alone.
PointF centerInWorld = GetPoint(center);
// Estimate the radius in world space.
// Get scalar will assumes reference direction to be X-axis in image space.
float radiusInWorld = GetScalar(radius);
// Get the intersection points of a horizontal diameter.
// This is used to draw a line from the center to the outline of the ellipse in perspective.
radiusLeftInImage = GetImagePoint(centerInWorld.Translate(-radiusInWorld, 0));
radiusRightInImage = GetImagePoint(centerInWorld.Translate(radiusInWorld, 0));
// Get the square enclosing the circle for mapping.
PointF a = GetImagePoint(centerInWorld.Translate(-radiusInWorld, -radiusInWorld));
PointF b = GetImagePoint(centerInWorld.Translate(radiusInWorld, -radiusInWorld));
PointF c = GetImagePoint(centerInWorld.Translate(radiusInWorld, radiusInWorld));
PointF d = GetImagePoint(centerInWorld.Translate(-radiusInWorld, radiusInWorld));
QuadrilateralF quadImage = new QuadrilateralF(a, b, c, d);
ProjectiveMapping mapping = new ProjectiveMapping();
mapping.Update(QuadrilateralF.CenteredUnitSquare, quadImage);
return(mapping.Ellipse());
}
/// <summary>
/// Takes a circle in real world coordinates and returns a cooresponding ellipse in image coordinates.
/// </summary>
public Ellipse GetEllipseFromCircle(PointF center, float radius)
{
if (calibratorType == CalibratorType.Line)
{
return(new Ellipse(GetImagePoint(center), GetImageScalar(radius), GetImageScalar(radius), 0));
}
// Get the square enclosing the circle for mapping.
PointF a = GetImagePoint(center.Translate(-radius, -radius));
PointF b = GetImagePoint(center.Translate(radius, -radius));
PointF c = GetImagePoint(center.Translate(radius, radius));
PointF d = GetImagePoint(center.Translate(-radius, radius));
QuadrilateralF quadImage = new QuadrilateralF(a, b, c, d);
ProjectiveMapping mapping = new ProjectiveMapping();
mapping.Update(QuadrilateralF.CenteredUnitSquare, quadImage);
return(mapping.Ellipse());
}
private void DrawDistortedLine(Graphics canvas, Pen pen, PointF a, PointF b, ProjectiveMapping projectiveMapping, DistortionHelper distorter, IImageToViewportTransformer transformer)
{
a = projectiveMapping.Forward(a);
b = projectiveMapping.Forward(b);
if (distorter != null && distorter.Initialized)
{
a = distorter.Distort(a);
b = distorter.Distort(b);
List <PointF> curve = distorter.DistortLine(a, b);
List <Point> transformed = transformer.Transform(curve);
canvas.DrawCurve(penEdges, transformed.ToArray());
}
else
{
canvas.DrawLine(pen, transformer.Transform(a), transformer.Transform(b));
}
}
private void DrawGrid(Graphics canvas, Pen pen, ProjectiveMapping projectiveMapping, DistortionHelper distorter, IImageToViewportTransformer transformer)
{
int start = 0;
int end = styleHelper.GridDivisions;
int total = styleHelper.GridDivisions;
// Horizontals
for (int i = start; i <= end; i++)
{
float v = i * ((float)planeHeight / total);
DrawDistortedLine(canvas, pen, new PointF(0, v), new PointF(planeWidth, v), projectiveMapping, distorter, transformer);
}
// Verticals
for (int i = start; i <= end; i++)
{
float h = i * (planeWidth / total);
DrawDistortedLine(canvas, pen, new PointF(h, 0), new PointF(h, planeHeight), projectiveMapping, distorter, transformer);
}
}
private void DrawDiagonals(Graphics canvas, Pen pen, QuadrilateralF quadPlane, ProjectiveMapping projectiveMapping, DistortionHelper distorter, IImageToViewportTransformer transformer)
{
DrawDistortedLine(canvas, penEdges, quadPlane.A, quadPlane.B, projectiveMapping, distorter, transformer);
DrawDistortedLine(canvas, penEdges, quadPlane.B, quadPlane.C, projectiveMapping, distorter, transformer);
DrawDistortedLine(canvas, penEdges, quadPlane.C, quadPlane.D, projectiveMapping, distorter, transformer);
DrawDistortedLine(canvas, penEdges, quadPlane.D, quadPlane.A, projectiveMapping, distorter, transformer);
DrawDistortedLine(canvas, penEdges, quadPlane.A, quadPlane.C, projectiveMapping, distorter, transformer);
DrawDistortedLine(canvas, penEdges, quadPlane.B, quadPlane.D, projectiveMapping, distorter, transformer);
}
