/// <summary>
/// returns an ideal grid with perfectly regular spacing
/// </summary>
/// <param name="grid"></param>
/// <param name="image_width"></param>
/// <param name="image_height"></param>
/// <returns>
/// </returns>
private static grid2D GetIdealGrid(CalibrationDot[,] grid,
int image_width, int image_height)
{
grid2D ideal_grid = null;
float ideal_spacing = 0;
double centre_x = image_width / 2;
double centre_y = image_height / 2;
double min_dist = double.MaxValue;
int grid_cx=0, grid_cy=0;
for (int x = 0; x < grid.GetLength(0); x++)
{
for (int y = 0; y < grid.GetLength(1); y++)
{
if (grid[x, y] != null)
{
double dx = grid[x, y].x - centre_x;
double dy = grid[x, y].y - centre_y;
double dist = dx*dx + dy*dy;
if (dist < min_dist)
{
min_dist = dist;
grid_cx = x;
grid_cy = y;
}
}
}
}
if (grid_cx > 0)
{
int[] orientation_histogram = new int[361];
List<double>[] orientations = new List<double>[361];
double average_dist = 0;
int hits = 0;
int local_search = 2;
for (int x = grid_cx - local_search; x <= grid_cx + local_search; x++)
{
if ((x >= 0) && (x < grid.GetLength(0)-1))
{
for (int y = grid_cy - local_search; y <= grid_cy + local_search; y++)
{
if ((y >= 1) && (y < grid.GetLength(1)-1))
{
if (grid[x, y] != null)
{
for (int i = 0; i < grid[x, y].Links.Count; i++)
{
CalibrationLink link = (CalibrationLink)grid[x, y].Links[i];
CalibrationDot from_dot = (CalibrationDot)link.From;
double dx = grid[x, y].x - from_dot.x;
double dy = grid[x, y].y - from_dot.y;
double dist = Math.Sqrt(dx*dx + dy*dy);
if (dist > 0)
{
double orientation = Math.Asin(dx / dist);
if (orientation < 0) orientation += Math.PI;
if (dy < 0) orientation = (Math.PI * 2) - orientation;
orientation = orientation / Math.PI * 180;
int bucket = (int)orientation;
orientation_histogram[bucket]++;
if (orientations[bucket] == null) orientations[bucket] = new List<double>();
orientations[bucket].Add(orientation);
average_dist += Math.Sqrt(dx*dx + dy*dy);
hits++;
}
}
}
}
}
}
}
if (hits > 0) average_dist = average_dist / hits;
ideal_spacing = (float)average_dist;
int max_orientation_response = 0;
int best_ang = 0;
for (int ang = 0; ang < 90; ang++)
{
int response = orientation_histogram[ang] +
orientation_histogram[ang + 90] +
orientation_histogram[ang + 180];
if (response > max_orientation_response)
{
max_orientation_response = response;
best_ang = ang;
}
}
double average_orientation = 0;
hits = 0;
for (int offset = 0; offset < 3; offset++)
{
if (orientations[best_ang + offset] != null)
{
for (int ang = 0; ang < orientations[best_ang + offset].Count; ang++)
{
average_orientation += orientations[best_ang + offset][ang] - (Math.PI*offset/2);
hits++;
}
}
}
if (hits > 0)
{
average_orientation /= hits;
float pattern_orientation = (float)average_orientation;
float offset_x = (float)grid[grid_cx, grid_cy].x;
float offset_y = (float)grid[grid_cx, grid_cy].y;
float r = ideal_spacing * dots_across;
polygon2D perimeter = new polygon2D();
perimeter.Add(-r + offset_x, -r + offset_y);
perimeter.Add(r + offset_x, -r + offset_y);
perimeter.Add(r + offset_x, r + offset_y);
perimeter.Add(-r + offset_x, r + offset_y);
perimeter.rotate((float)average_orientation / 180 * (float)Math.PI, offset_x, offset_y);
ideal_grid = new grid2D(dots_across*2, dots_across*2, perimeter, 0, false);
int grid_width = grid.GetLength(0);
int grid_height = grid.GetLength(1);
int idx = 0;
int xx=0, yy=0;
float ideal_x, ideal_y;
for (int orient = 0; orient < 8; orient++)
{
for (int x = 0; x < grid_width; x++)
{
for (int y = 0; y < grid_height; y++)
{
if (grid[x, y] != null)
{
switch(orient)
{
case 0:
{
xx = (x - grid_cx) + dots_across;
yy = (y - grid_cy) + dots_across;
break;
}
case 1:
{
xx = (x - grid_cx) + dots_across;
yy = (grid_cy - y) + dots_across;
break;
}
case 2:
{
xx = (grid_cx - x) + dots_across;
yy = (y - grid_cy) + dots_across;
break;
}
case 3:
{
xx = (grid_cx - x) + dots_across;
yy = (grid_cy - y) + dots_across;
break;
}
case 4:
{
xx = (y - grid_cy) + dots_across;
yy = (x - grid_cx) + dots_across;
break;
}
case 5:
{
xx = (y - grid_cy) + dots_across;
yy = (grid_cx - x) + dots_across;
break;
}
case 6:
{
xx = (grid_cy - y) + dots_across;
yy = (x - grid_cx) + dots_across;
break;
}
case 7:
{
xx = (grid_cy - y) + dots_across;
yy = (grid_cx - x) + dots_across;
break;
}
}
if ((xx >= 0) && (xx < ideal_grid.cell.Length) &&
(yy >= 0) && (yy < ideal_grid.cell[0].Length))
{
ideal_x = ideal_grid.cell[xx][yy].perimeter.x_points[idx];
ideal_y = ideal_grid.cell[xx][yy].perimeter.y_points[idx];
if (orient == 0)
{
grid[x, y].rectified_x = ideal_x;
grid[x, y].rectified_y = ideal_y;
}
else
{
double diff_x1 = grid[x, y].rectified_x - grid[x, y].x;
double diff_y1 = grid[x, y].rectified_y - grid[x, y].y;
double dist1 = diff_x1*diff_x1 + diff_y1*diff_y1;
double diff_x2 = ideal_x - grid[x, y].x;
double diff_y2 = ideal_y - grid[x, y].y;
double dist2 = diff_x2*diff_x2 + diff_y2*diff_y2;
if (dist2 < dist1)
{
grid[x, y].rectified_x = ideal_x;
grid[x, y].rectified_y = ideal_y;
}
}
}
}
}
}
}
}
}
return(ideal_grid);
}
