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projection from lat/lon to nearest point on road network has been reworked and is more precise (Thanks again Bharath!)

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This commit is contained in:
Dennis Luxen 2011-05-24 13:52:51 +00:00
parent 8d5c42d7f8
commit fba77ff459
1 changed files with 34 additions and 31 deletions
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53
DataStructures/NNGrid.h
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@ -584,40 +584,43 @@ private:
}
}
/* More or less from monav project, thanks */
double ComputeDistance(const _Coordinate& inputPoint, const _Coordinate& source, const _Coordinate& target, _Coordinate& nearest, double *r) {
const double vY = (double)target.lon - (double)source.lon;
const double vX = (double)target.lat - (double)source.lat;
const double wY = (double)inputPoint.lon - (double)source.lon;
const double wX = (double)inputPoint.lat - (double)source.lat;
const double lengthSquared = vX * vX + vY * vY;
if(lengthSquared != 0) {
*r = (vX * wX + vY * wY) / lengthSquared;
const double x = (double)inputPoint.lat;
const double y = (double)inputPoint.lon;
const double a = (double)source.lat;
const double b = (double)source.lon;
const double c = (double)target.lat;
const double d = (double)target.lon;
double p,q,mX,nY;
if(c != a){
const double m = (d-b)/(c-a); // slope
// Projection of (x,y) on line joining (a,b) and (c,d)
p = ((x + (m*y)) + (m*m*a - m*b))/(1 + m*m);
q = b + m*(p - a);
}
double percentage = *r;
if(*r <=0 ) {
else{
p = c;
q = y;
}
nY = (d*p - c*q)/(a*d - b*c);
mX = (p - nY*a)/c;// These values are actually n/m+n and m/m+n , we neednot calculate the values of m an n as we are just interested in the ratio
*r = mX;
if(*r<=0){
nearest.lat = source.lat;
nearest.lon = source.lon;
percentage = 0;
return wY * wY + wX * wX;
return ((b - y)*(b - y) + (a - x)*(a - x));
}
if( *r>= 1) {
else if(*r >= 1){
nearest.lat = target.lat;
nearest.lon = target.lon;
percentage = 1;
const double dY = (double)inputPoint.lon - (double)target.lon;
const double dX = (double)inputPoint.lat - (double)target.lat;
return dY * dY + dX * dX;
}
return ((d - y)*(d - y) + (c - x)*(c - x));
nearest.lat = (double)source.lat + ( (*r) * vX );
nearest.lon = (double)source.lon + ( (*r) * vY );
const double dX = (double)source.lat + (*r) * vX - (double)inputPoint.lat;
const double dY = (double)source.lon + (*r) * vY - (double)inputPoint.lon;
return dY*dY + dX*dX;
}
// point lies in between
nearest.lat = p;
nearest.lon = q;
return (p-x)*(p-x) + (q-y)*(q-y);
}
ofstream indexOutFile;