ref: c33c7ca85fa7b28658f3b086d579a7fbbcf41dea
dir: /tools/3D-Reconstruction/sketch_3D_reconstruction/MotionField.pde/
class MotionField {
int block_size;
ArrayList<PVector> motion_field;
MotionField(int block_size) {
this.block_size = block_size;
motion_field = new ArrayList<PVector>();
}
void update(Camera last_cam, Camera current_cam, PointCloud point_cloud,
BVH bvh) {
// clear motion field
motion_field = new ArrayList<PVector>();
int r_num = height / block_size, c_num = width / block_size;
for (int i = 0; i < r_num * c_num; i++)
motion_field.add(new PVector(0, 0, 0));
// estimate motion vector of each point in point cloud
for (int i = 0; i < point_cloud.size(); i++) {
PVector p = point_cloud.getPosition(i);
PVector p0 = current_cam.project(p);
PVector p1 = last_cam.project(p);
int row = int((p0.y + height / 2.0f) / block_size);
int col = int((p0.x + width / 2.0f) / block_size);
if (row >= 0 && row < r_num && col >= 0 && col < c_num) {
PVector accu = motion_field.get(row * c_num + col);
accu.x += p1.x - p0.x;
accu.y += p1.y - p0.y;
accu.z += 1;
}
}
// if some blocks do not have point, then use ray tracing to see if they are
// in triangles
for (int i = 0; i < r_num; i++)
for (int j = 0; j < c_num; j++) {
PVector accu = motion_field.get(i * c_num + j);
if (accu.z > 0) {
continue;
}
// use the center of the block to generate view ray
float cx = j * block_size + block_size / 2.0f - width / 2.0f;
float cy = i * block_size + block_size / 2.0f - height / 2.0f;
float cz = 0.5f * height / tan(current_cam.fov / 2.0f);
PVector dir = new PVector(cx, cy, cz);
float[] camMat = current_cam.getCameraMat();
dir = MatxVec3(transpose3x3(camMat), dir);
dir.normalize();
Ray r = new Ray(current_cam.pos, dir);
// ray tracing
float[] param = new float[4];
param[0] = Float.POSITIVE_INFINITY;
if (bvh.intersect(r, param)) {
PVector p = new PVector(param[1], param[2], param[3]);
PVector p0 = current_cam.project(p);
PVector p1 = last_cam.project(p);
accu.x += p1.x - p0.x;
accu.y += p1.y - p0.y;
accu.z += 1;
}
}
// estimate the motion vector of each block
for (int i = 0; i < r_num * c_num; i++) {
PVector mv = motion_field.get(i);
if (mv.z > 0) {
motion_field.set(i, new PVector(mv.x / mv.z, mv.y / mv.z, 0));
} else // there is nothing in the block, use -1 to mark it.
{
motion_field.set(i, new PVector(0.0, 0.0, -1));
}
}
}
void render() {
int r_num = height / block_size, c_num = width / block_size;
for (int i = 0; i < r_num; i++)
for (int j = 0; j < c_num; j++) {
PVector mv = motion_field.get(i * c_num + j);
float ox = j * block_size + 0.5f * block_size;
float oy = i * block_size + 0.5f * block_size;
stroke(255, 0, 0);
line(ox, oy, ox + mv.x, oy + mv.y);
}
}
void save(String path) {
int r_num = height / block_size;
int c_num = width / block_size;
String[] mvs = new String[r_num];
for (int i = 0; i < r_num; i++) {
mvs[i] = "";
for (int j = 0; j < c_num; j++) {
PVector mv = motion_field.get(i * c_num + j);
if (mv.z != -1) {
mvs[i] += str(mv.x) + "," + str(mv.y);
} else // there is nothing
{
mvs[i] += "-,-";
}
if (j != c_num - 1) mvs[i] += ";";
}
}
saveStrings(path, mvs);
}
}