/// <summary>
/// extracts lines from the given detected dots
/// </summary>
/// <param name="dots"></param>
/// <returns></returns>
private static List<List<double>> CreateLines(hypergraph dots,
calibrationDot[,] grid)
{
List<List<double>> lines = new List<List<double>>();
if (grid != null)
{
for (int grid_x = 0; grid_x < grid.GetLength(0); grid_x++)
{
List<double> line = new List<double>();
for (int grid_y = 0; grid_y < grid.GetLength(1); grid_y++)
{
if (grid[grid_x, grid_y] != null)
{
line.Add(grid[grid_x, grid_y].x);
line.Add(grid[grid_x, grid_y].y);
}
}
if (line.Count > 6)
{
lines.Add(line);
}
}
for (int grid_y = 0; grid_y < grid.GetLength(1); grid_y++)
{
List<double> line = new List<double>();
for (int grid_x = 0; grid_x < grid.GetLength(0); grid_x++)
{
if (grid[grid_x, grid_y] != null)
{
line.Add(grid[grid_x, grid_y].x);
line.Add(grid[grid_x, grid_y].y);
}
}
if (line.Count > 6)
{
lines.Add(line);
}
}
}
return (lines);
}
/// <summary>
/// returns an ideally spaced grid over the actual detected spots
/// </summary>
/// <param name="grid"></param>
/// <returns></returns>
private static grid2D OverlayIdealGrid(calibrationDot[,] grid,
List<calibrationDot> corners,
ref int grid_offset_x, ref int grid_offset_y,
int random_seed)
{
grid2D overlay_grid = null;
int grid_tx = -1;
int grid_ty = -1;
int grid_bx = -1;
int grid_by = -1;
int offset_x = 0;
int offset_y = 0;
bool found = false;
int max_region_area = 0;
// try searching horizontally and vertically
// then pick the result with the greatest area
for (int test_orientation = 0; test_orientation < 2; test_orientation++)
{
bool temp_found = false;
int temp_grid_tx = -1;
int temp_grid_ty = -1;
int temp_grid_bx = -1;
int temp_grid_by = -1;
int temp_offset_x = 0;
int temp_offset_y = 0;
switch (test_orientation)
{
case 0:
{
while ((temp_offset_y < 5) && (!temp_found))
{
temp_offset_x = 0;
while ((temp_offset_x < 3) && (!temp_found))
{
temp_grid_tx = temp_offset_x;
temp_grid_ty = temp_offset_y;
temp_grid_bx = grid.GetLength(0) - 1 - temp_offset_x;
temp_grid_by = grid.GetLength(1) - 1 - temp_offset_y;
if ((temp_grid_bx < grid.GetLength(0)) &&
(temp_grid_tx < grid.GetLength(0)) &&
(temp_grid_by < grid.GetLength(1)) &&
(temp_grid_ty < grid.GetLength(1)) &&
(temp_grid_ty >= 0) &&
(temp_grid_by >= 0) &&
(temp_grid_tx >= 0) &&
(temp_grid_bx >= 0))
{
if ((grid[temp_grid_tx, temp_grid_ty] != null) &&
(grid[temp_grid_bx, temp_grid_ty] != null) &&
(grid[temp_grid_bx, temp_grid_by] != null) &&
(grid[temp_grid_tx, temp_grid_by] != null))
{
temp_found = true;
}
}
temp_offset_x++;
}
temp_offset_y++;
}
break;
}
case 1:
{
while ((temp_offset_x < 3) && (!temp_found))
{
temp_offset_y = 0;
while ((temp_offset_y < 5) && (!temp_found))
{
temp_grid_tx = temp_offset_x;
temp_grid_ty = temp_offset_y;
temp_grid_bx = grid.GetLength(0) - 1 - temp_offset_x;
temp_grid_by = grid.GetLength(1) - 1 - temp_offset_y;
if ((temp_grid_bx < grid.GetLength(0)) &&
(temp_grid_tx < grid.GetLength(0)) &&
(temp_grid_by < grid.GetLength(1)) &&
(temp_grid_ty < grid.GetLength(1)) &&
(temp_grid_ty >= 0) &&
(temp_grid_by >= 0) &&
(temp_grid_tx >= 0) &&
(temp_grid_bx >= 0))
{
if ((grid[temp_grid_tx, temp_grid_ty] != null) &&
(grid[temp_grid_bx, temp_grid_ty] != null) &&
(grid[temp_grid_bx, temp_grid_by] != null) &&
(grid[temp_grid_tx, temp_grid_by] != null))
{
temp_found = true;
}
}
temp_offset_y++;
}
temp_offset_x++;
}
break;
}
}
temp_offset_y = temp_grid_ty - 1;
while (temp_offset_y >= 0)
{
if ((temp_offset_y < grid.GetLength(1)) &&
(temp_offset_y >= 0))
{
if ((grid[temp_grid_tx, temp_offset_y] != null) &&
(grid[temp_grid_bx, temp_offset_y] != null))
{
temp_grid_ty = temp_offset_y;
temp_offset_y--;
}
else break;
}
else break;
}
temp_offset_y = temp_grid_by + 1;
while (temp_offset_y < grid.GetLength(1))
{
if ((temp_offset_y < grid.GetLength(1)) &&
(temp_offset_y >= 0))
{
if ((grid[temp_grid_tx, temp_offset_y] != null) &&
(grid[temp_grid_bx, temp_offset_y] != null))
{
temp_grid_by = temp_offset_y;
temp_offset_y++;
}
else break;
}
else break;
}
if (temp_found)
{
int region_area = (temp_grid_bx - temp_grid_tx) * (temp_grid_by - temp_grid_ty);
if (region_area > max_region_area)
{
max_region_area = region_area;
found = true;
grid_tx = temp_grid_tx;
grid_ty = temp_grid_ty;
grid_bx = temp_grid_bx;
grid_by = temp_grid_by;
offset_x = temp_offset_x;
offset_y = temp_offset_y;
}
}
}
if (found)
{
// record the positions of the corners
corners.Add(grid[grid_tx, grid_ty]);
corners.Add(grid[grid_bx, grid_ty]);
corners.Add(grid[grid_bx, grid_by]);
corners.Add(grid[grid_tx, grid_by]);
double dx, dy;
double x0 = grid[grid_tx, grid_ty].x;
double y0 = grid[grid_tx, grid_ty].y;
double x1 = grid[grid_bx, grid_ty].x;
double y1 = grid[grid_bx, grid_ty].y;
double x2 = grid[grid_tx, grid_by].x;
double y2 = grid[grid_tx, grid_by].y;
double x3 = grid[grid_bx, grid_by].x;
double y3 = grid[grid_bx, grid_by].y;
polygon2D perimeter = new polygon2D();
perimeter.Add((float)x0, (float)y0);
perimeter.Add((float)x1, (float)y1);
perimeter.Add((float)x3, (float)y3);
perimeter.Add((float)x2, (float)y2);
int grid_width = grid_bx - grid_tx;
int grid_height = grid_by - grid_ty;
int min_hits = 0;
double min_dx = 0, min_dy = 0;
// try various perimeter sizes
double min_dist = double.MaxValue;
int max_perim_size_tries = 100;
polygon2D best_perimeter = perimeter;
MersenneTwister rnd = new MersenneTwister(random_seed);
for (int perim_size = 0; perim_size < max_perim_size_tries; perim_size++)
{
// try a small range of translations
for (int nudge_x = -10; nudge_x <= 10; nudge_x++)
{
for (int nudge_y = -5; nudge_y <= 5; nudge_y++)
{
// create a perimeter at this scale and translation
polygon2D temp_perimeter = perimeter.Scale(1.0f + (perim_size * 0.1f / max_perim_size_tries));
temp_perimeter = temp_perimeter.ScaleSideLength(0, 0.95f + ((float)rnd.NextDouble() * 0.1f));
temp_perimeter = temp_perimeter.ScaleSideLength(2, 0.95f + ((float)rnd.NextDouble() * 0.1f));
for (int i = 0; i < temp_perimeter.x_points.Count; i++)
{
temp_perimeter.x_points[i] += nudge_x;
temp_perimeter.y_points[i] += nudge_y;
}
// create a grid based upon the perimeter
grid2D temp_overlay_grid = new grid2D(grid_width, grid_height, temp_perimeter, 0, false);
// how closely does the grid fit the actual observations ?
double temp_min_dist = min_dist;
BestFit(grid_tx, grid_ty, grid,
temp_overlay_grid, ref min_dist,
ref min_dx, ref min_dy, ref min_hits,
ref grid_offset_x, ref grid_offset_y);
// record the closest fit
if (temp_min_dist < min_dist)
{
best_perimeter = temp_perimeter;
overlay_grid = temp_overlay_grid;
}
}
}
}
if (min_hits > 0)
{
dx = min_dx;
dy = min_dy;
Console.WriteLine("dx: " + dx.ToString());
Console.WriteLine("dy: " + dy.ToString());
x0 += dx;
y0 += dy;
x1 += dx;
y1 += dy;
x2 += dx;
y2 += dy;
x3 += dx;
y3 += dy;
perimeter = new polygon2D();
perimeter.Add((float)x0, (float)y0);
perimeter.Add((float)x1, (float)y1);
perimeter.Add((float)x3, (float)y3);
perimeter.Add((float)x2, (float)y2);
overlay_grid = new grid2D(grid_width, grid_height, perimeter, 0, false);
}
}
return (overlay_grid);
}
/// <summary>
/// fits a curve to the given grid using the given centre of distortion
/// </summary>
/// <param name="grid">detected grid dots</param>
/// <param name="overlay_grid">overlayed ideal rectified grid</param>
/// <param name="centre_of_distortion">centre of lens distortion</param>
/// <param name="curve">curve to be fitted</param>
private static void FitCurve(calibrationDot[,] grid,
grid2D overlay_grid,
calibrationDot centre_of_distortion,
polynomial curve,
double noise, MersenneTwister rnd,
int grid_offset_x, int grid_offset_y)
{
double[] prev_col = new double[grid.GetLength(1) * 2];
double[] col = new double[prev_col.Length];
double half_noise = noise / 2;
double rectified_x, rectified_y;
for (int pass = 0; pass < 1; pass++)
{
// for every detected dot
for (int grid_x = 0; grid_x < grid.GetLength(0); grid_x++)
{
double prev_rectified_radial_dist = 0;
double prev_actual_radial_dist = 0;
int prev_grid_y = -1;
for (int grid_y = 0; grid_y < grid.GetLength(1); grid_y++)
{
if (grid[grid_x, grid_y] != null)
{
if ((grid_x + grid_offset_x < overlay_grid.line_intercepts.GetLength(0)) &&
(grid_y + grid_offset_y < overlay_grid.line_intercepts.GetLength(1)) &&
(grid_x + grid_offset_x >= 0) && (grid_y + grid_offset_y >= 0))
{
// find the rectified distance of the dot from the centre of distortion
rectified_x = overlay_grid.line_intercepts[grid_x + grid_offset_x, grid_y + grid_offset_y, 0];
rectified_y = overlay_grid.line_intercepts[grid_x + grid_offset_x, grid_y + grid_offset_y, 1];
if (pass > 0)
{
rectified_x += (((rnd.NextDouble() * noise) - half_noise) * 0.1);
rectified_y += (((rnd.NextDouble() * noise) - half_noise) * 0.1);
}
//double rectified_x = overlay_grid.line_intercepts[grid_x + grid_offset_x, grid_y + grid_offset_y, 0];
//double rectified_y = overlay_grid.line_intercepts[grid_x + grid_offset_x, grid_y + grid_offset_y, 1];
double rectified_dx = rectified_x - centre_of_distortion.x;
double rectified_dy = rectified_y - centre_of_distortion.y;
double rectified_radial_dist = Math.Sqrt(rectified_dx * rectified_dx + rectified_dy * rectified_dy);
// find the actual raw image distance of the dot from the centre of distortion
//double actual_x = grid[grid_x, grid_y].x + (((rnd.NextDouble() * noise) - half_noise) * 2);
//double actual_y = grid[grid_x, grid_y].y + (((rnd.NextDouble() * noise) - half_noise) * 2);
double actual_x = grid[grid_x, grid_y].x;
double actual_y = grid[grid_x, grid_y].y;
double actual_dx = actual_x - centre_of_distortion.x;
double actual_dy = actual_y - centre_of_distortion.y;
double actual_radial_dist = Math.Sqrt(actual_dx * actual_dx + actual_dy * actual_dy);
// plot
curve.AddPoint(rectified_radial_dist, actual_radial_dist);
col[(grid_y * 2)] = rectified_radial_dist;
col[(grid_y * 2) + 1] = actual_radial_dist;
prev_rectified_radial_dist = rectified_radial_dist;
prev_actual_radial_dist = actual_radial_dist;
prev_grid_y = grid_y;
}
}
}
for (int i = 0; i < col.Length; i++)
prev_col[i] = col[i];
}
}
// find the best fit curve
curve.Solve();
}
private static void BestFit(int grid_tx, int grid_ty,
calibrationDot[,] grid,
grid2D overlay_grid,
ref double min_dist,
ref double min_dx, ref double min_dy,
ref int min_hits,
ref int grid_offset_x, ref int grid_offset_y)
{
for (int off_x = -1; off_x <= 1; off_x++)
{
for (int off_y = -1; off_y <= 1; off_y++)
{
int grid_x_offset = -grid_tx + off_x;
int grid_y_offset = -grid_ty + off_y;
int grid_x_offset_start = 0;
int grid_x_offset_end = 0;
if (grid_x_offset < 0)
{
grid_x_offset_start = -grid_x_offset;
grid_x_offset_end = 0;
}
else
{
grid_x_offset_start = 0;
grid_x_offset_end = grid_x_offset;
}
int grid_y_offset_start = 0;
int grid_y_offset_end = 0;
if (grid_y_offset < 0)
{
grid_y_offset_start = -grid_y_offset;
grid_y_offset_end = 0;
}
else
{
grid_y_offset_start = 0;
grid_y_offset_end = grid_y_offset;
}
double dx = 0;
double dy = 0;
double dist = 0;
int hits = 0;
for (int grid_x = grid_x_offset_start; grid_x < grid.GetLength(0) - grid_x_offset_end; grid_x++)
{
for (int grid_y = grid_y_offset_start; grid_y < grid.GetLength(1) - grid_y_offset_end; grid_y++)
{
if (grid[grid_x, grid_y] != null)
{
if ((grid_x + grid_x_offset < overlay_grid.line_intercepts.GetLength(0)) &&
(grid_y + grid_y_offset < overlay_grid.line_intercepts.GetLength(1)))
{
double intercept_x = overlay_grid.line_intercepts[grid_x + grid_x_offset, grid_y + grid_y_offset, 0];
double intercept_y = overlay_grid.line_intercepts[grid_x + grid_x_offset, grid_y + grid_y_offset, 1];
double dxx = grid[grid_x, grid_y].x - intercept_x;
double dyy = grid[grid_x, grid_y].y - intercept_y;
dx += dxx;
dy += dyy;
dist += Math.Abs(dxx) + Math.Abs(dyy);
hits++;
}
}
}
}
if (hits > 0)
{
dx /= hits;
dy /= hits;
//double dist = Math.Sqrt(dx * dx + dy * dy);
if (dist < min_dist)
{
min_dist = dist;
min_dx = dx;
min_dy = dy;
min_hits = hits;
grid_offset_x = grid_x_offset;
grid_offset_y = grid_y_offset;
}
}
}
}
}
private static double DetectCameraRotation(int image_width, int image_height,
calibrationDot[,] grid,
polynomial curve,
calibrationDot centre_of_distortion,
ref List<List<double>> rectified_centre_line,
double scale)
{
double rotation = 0;
List<List<double>> centre_line = new List<List<double>>();
List<double> line = new List<double>();
// get the vertical centre line within the image
for (int grid_y = 0; grid_y < grid.GetLength(1); grid_y++)
{
int grid_x = 0;
bool found = false;
while ((grid_x < grid.GetLength(0)) && (!found))
{
if (grid[grid_x, grid_y] != null)
{
if (grid[grid_x, grid_y].grid_x == 0)
{
line.Add(grid[grid_x, grid_y].x);
line.Add(grid[grid_x, grid_y].y);
found = true;
}
}
grid_x++;
}
}
centre_line.Add(line);
// rectify the centre line
rectified_centre_line =
RectifyLines(centre_line, image_width, image_height,
curve, centre_of_distortion, 0, scale);
if (rectified_centre_line != null)
{
if (rectified_centre_line.Count > 0)
{
double[] px = new double[2];
double[] py = new double[2];
int[] hits = new int[2];
line = rectified_centre_line[0];
for (int i = 0; i < line.Count; i += 2)
{
double x = line[i];
double y = line[i + 1];
if (i < line.Count / 2)
{
px[0] += x;
py[0] += y;
hits[0]++;
}
else
{
px[1] += x;
py[1] += y;
hits[1]++;
}
}
if ((hits[0] > 0) && (hits[1] > 0))
{
px[0] /= hits[0];
py[0] /= hits[0];
px[1] /= hits[1];
py[1] /= hits[1];
double dx = px[1] - px[0];
double dy = py[1] - py[0];
double length = Math.Sqrt(dx * dx + dy * dy);
if (length > 0)
rotation = Math.Asin(dx / length);
}
}
}
return (rotation);
}
