Page 236 - The Definitive Guide to Building Java Robots

Preston_5564C06.fm Page 217 Friday, September 23, 2005 5:13 AM

CHAPTER 6 ■ VISION 217

int maxPoints = 0;
double totalPoints = 0;
// move through image row by row from top to bottom

for (int y = 0; y < h; ++y) {
for (int x = 0; x < w; ++x) {
int srcPixel = srcImg.getRGB(x, y);
Color c = new Color(srcPixel);
// build accumulator image
// this will get the grey value of the image
// even though i get red here, they are all same value.
int colorValue = getGrey(c).getRed();
// if color is white, then we want to move through all
// lines at this point
if (colorValue == 255) {
// moving through each line from zero to max angle
// at resolution defined.
for (int theta = 0; theta < angle_range; theta = theta + aRes) {
// get the angle 0-90
double radians = (theta / 180.0) * Math.PI ;
// get potential line
// p = radius
// radians = angle
// x = x-coordinate
// y = y-coordinate
int p = (int) (Math.cos(radians) * x + Math
.sin(radians)
* y);
// get absolute radius
p = Math.abs(p);
// add the accumulator at this angle and radius
acc[p][theta] = acc[p][theta] + 1;
// want to add the total points accumulated
totalPoints = totalPoints + acc[p][theta];
// get the maximum number of points accumulated
// for a particular bin
if (acc[p][theta] > maxPoints) {
maxPoints = acc[p][theta];
}
}
}
}
}
// now work with the parameters space of the accumulator to find the x,y
// coordinates of the lines
// a = normalized to width
// b = normalized height