/**
* Performs an exhaustive search centered around (cx,cy) for the region in 'curr' which is the
* best match for the template. Results are written into 'flow'
*/
protected float findFlow(int cx, int cy, T curr, ImageFlow.D flow) {
float bestScore = Float.MAX_VALUE;
int bestFlowX = 0, bestFlowY = 0;
for (int i = -searchRadius; i <= searchRadius; i++) {
int y = cy + i;
for (int j = -searchRadius; j <= searchRadius; j++) {
int x = cx + j;
float error = computeError(x, y, curr);
if (error < bestScore) {
bestScore = error;
bestFlowX = j;
bestFlowY = i;
} else if (error == bestScore) {
// Pick solution with the least motion when ambiguous
float m0 = j * j + i * i;
float m1 = bestFlowX * bestFlowX + bestFlowY * bestFlowY;
if (m0 < m1) {
bestFlowX = j;
bestFlowY = i;
}
}
}
}
if (bestScore <= maxError) {
flow.valid = true;
flow.x = bestFlowX;
flow.y = bestFlowY;
return bestScore;
} else {
flow.valid = false;
return Float.NaN;
}
}
@Test
public void checkNeighbors() {
int r = 3;
Dummy alg = new Dummy(r, 2, 200, ImageUInt8.class);
alg.scores = new float[20 * 30];
ImageFlow flows = new ImageFlow(20, 30);
ImageFlow.D tmp = new ImageFlow.D();
tmp.valid = true;
tmp.x = -1;
tmp.y = 2;
// checks to see if a pixel is invalid that it's flow is always set
// if a pixel is valid then the score is only set if the score is better
flows.get(6, 5).valid = true;
alg.scores[5 * 20 + 6] = 10;
flows.get(5, 5).valid = true;
alg.scores[5 * 20 + 5] = 4;
// same score, but more motion
flows.get(5, 6).valid = true;
alg.scores[6 * 20 + 5] = 5;
flows.get(5, 6).x = 2;
flows.get(5, 6).y = 2;
// same score, but less motion
flows.get(6, 6).valid = true;
alg.scores[6 * 20 + 6] = 5;
flows.get(6, 6).x = 0;
flows.get(6, 6).y = 1;
alg.checkNeighbors(6, 7, tmp, flows, 5);
for (int i = -r; i <= r; i++) {
for (int j = -r; j <= r; j++) {
int x = j + 6;
int y = i + 7;
ImageFlow.D f = flows.get(x, y);
assertTrue(f.valid);
if (x == 5 && y == 5) {
assertEquals(4, alg.scores[y * 20 + x], 1e-4);
assertEquals(0, f.x, 1e-4);
assertEquals(0, f.y, 1e-4);
} else if (x == 6 && y == 6) {
assertEquals(5, alg.scores[y * 20 + x], 1e-4);
assertEquals(0, f.x, 1e-4);
assertEquals(1, f.y, 1e-4);
} else {
assertEquals(x + " " + y, 5, alg.scores[y * 20 + x], 1e-4);
assertEquals(-1, f.x, 1e-4);
assertEquals(2, f.y, 1e-4);
}
}
}
}
/**
* Examines every pixel inside the region centered at (cx,cy) to see if their optical flow has a
* worse score the one specified in 'flow'
*/
protected void checkNeighbors(int cx, int cy, ImageFlow.D flow, ImageFlow image, float score) {
for (int i = -searchRadius; i <= searchRadius; i++) {
int index = image.width * (cy + i) + (cx - searchRadius);
for (int j = -searchRadius; j <= searchRadius; j++, index++) {
float s = scores[index];
ImageFlow.D f = image.data[index];
if (!f.valid || s > score) {
f.set(flow);
scores[index] = score;
} else if (s == score) {
// Pick solution with the least motion when ambiguous
float m0 = f.x * f.x + f.y * f.y;
float m1 = flow.x * flow.x + flow.y * flow.y;
if (m1 < m0) {
f.set(flow);
scores[index] = score;
}
}
}
}
}