public Grid2D createSinogramm(Grid2D phantom, boolean filter) {
// Bouding Box
Box imageBox =
new Box(
phantom.getWidth() * phantom.getSpacing()[0],
phantom.getHeight() * phantom.getSpacing()[1],
2.0d);
imageBox.setLowerCorner(new PointND(phantom.getOrigin()[0], phantom.getOrigin()[1], -1.0));
imageBox.setUpperCorner(new PointND(-phantom.getOrigin()[0], -phantom.getOrigin()[1], 1.0));
// walk over each projection
for (int indexProjections = 0; indexProjections < projections; indexProjections++) {
// walk along the detector
for (int indexDetektor = 0; indexDetektor < numberPixel; indexDetektor++) {
// define the parallel lines of the detector
double[] indexWorld = this.indexToPhysical(indexDetektor, indexProjections);
double angle = angleWidthR * indexProjections;
double s = indexWorld[0];
double cos = Math.cos(angle);
double sin = Math.sin(angle);
PointND p1 = new PointND(cos * s, sin * s, 0.0d);
PointND p2 = new PointND(cos * s - sin, sin * s + cos, 0.0d);
StraightLine line = new StraightLine(p1, p2);
// intersection of the box and the line
ArrayList<PointND> crossingPoints = imageBox.intersect(line);
// if there is no intersection -> change direction of the line and look again
if (crossingPoints.size() == 0) {
p2 = new PointND(cos * s + sin, sin * s - cos, 0.0d);
line = new StraightLine(p1, p2);
crossingPoints = imageBox.intersect(line);
}
if (crossingPoints.size() == 2) {
PointND c1 = crossingPoints.get(0);
PointND c2 = crossingPoints.get(1);
// compute distance between intersectoin points
double distance = c1.euclideanDistance(c2);
// define the direction of the line
double deltax = (c2.get(0) - c1.get(0)) / (distance);
double deltay = (c2.get(1) - c1.get(1)) / (distance);
double deltaz = (c2.get(2) - c1.get(2)) / (distance);
PointND richtung = new PointND(deltax, deltay, deltaz);
// result value at the current position in the sinogramm
float val = 0.f;
// stepsize of the integral
double delta = 0.5; // in mm
// line integral
for (double k = 0; k < (distance); k = k + delta) {
double indexX = c1.get(0) + k * (richtung.get(0));
double indexY = c1.get(1) + k * (richtung.get(1));
double[] indexImage = phantom.physicalToIndex(indexX, indexY);
val += InterpolationOperators.interpolateLinear(phantom, indexImage[0], indexImage[1]);
}
this.setAtIndex(indexDetektor, indexProjections, (float) (val * delta));
}
}
}
if (filter == true) {
filtering(this);
}
Grid2D result = new Grid2D(this);
return result;
}
