/*!
Initialize a point feature with polar coordinates
\f$(\rho,\theta)\f$ using the coordinates of the point in pixels
obtained by image processing. This point is the center
of gravity of a dot tracked using vpDot. Using the camera
parameters, the pixels coordinates of the dot are first
converted in cartesian \f$(x,y)\f$ coordinates in meter in the
camera frame and than in polar coordinates by:
\f[\rho = \sqrt{x^2+y^2} \hbox{,}\; \; \theta = \arctan \frac{y}{x}\f]
\warning This function does not initialize \f$Z\f$ which is
requested to compute the interaction matrix by
vpfeaturePointPolar::interaction().
\param s : Visual feature \f$(\rho,\theta)\f$ to initialize. Be
aware, the 3D depth \f$Z\f$ requested to compute the interaction
matrix is not initialized by this function.
\param cam : Camera parameters.
\param dot : Tracked dot. The center of gravity corresponds to the
coordinates of the point in the image plane.
The code below shows how to initialize a vpFeaturePointPolar visual
feature. First, we initialize the \f$\rho,\theta\f$, and lastly we
set the 3D depth \f$Z\f$ of the point which is generally the result
of a pose estimation.
\code
vpImage<unsigned char> I; // Image container
vpCameraParameters cam; // Default intrinsic camera parameters
vpDot2 dot; // Dot tracker
vpFeaturePointPolar s; // Point feature with polar coordinates
...
// Tracking on the dot
dot.track(I);
// Initialize rho,theta visual feature
vpFeatureBuilder::create(s, cam, dot);
// A pose estimation is requested to initialize Z, the depth of the
// point in the camera frame.
double Z = 1; // Depth of the point in meters
....
s.set_Z(Z);
\endcode
*/
void vpFeatureBuilder::create(vpFeaturePointPolar &s,
const vpCameraParameters &cam,
const vpDot &dot)
{
try {
double x=0, y=0;
vpImagePoint cog;
cog = dot.getCog();
vpPixelMeterConversion::convertPoint(cam, cog, x, y) ;
double rho = sqrt(x*x + y*y);
double theta = atan2(y, x);
s.set_rho(rho) ;
s.set_theta(theta) ;
}
catch(...) {
vpERROR_TRACE("Error caught") ;
throw ;
}
}
bool
vpDot::operator==(const vpDot& d)
{
return ( cog == d.getCog() );
}