Read LiDar/LAS file in matlab.

January 11, 2010

Below is the c code for reading LiDar/LAS file into matlab. To compile the code, simply use
mex LASReader.cpp

The code reads the points coordinates only. Please see the code for details.

For details of LiDar file format, please visit this link.

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De Boor’s Algorithm in C++

October 18, 2009

Here is the c++ code for the De Boor algorithm. It calculates a point C(x) on a B-Spline curve of any degree.

Point deBoor(int k,int degree, int i, double x, double* knots, Point *ctrlPoints)
{   // Please see wikipedia page for detail
	// note that the algorithm here kind of traverses in reverse order
	// comapred to that in the wikipedia page
	if( k == 0)
		return ctrlPoints[i];
	else
	{   
		double alpha = (x-knots[i])/(knots[i+degree+1-k]-knots[i]);
		return (deBoor(k-1,degree, i-1, x, knots, ctrlPoints)*(1-alpha )+deBoor(k-1,degree, i, x, knots, ctrlPoints)*alpha );
	}
}

The Point class is defined as the follow:

class Point
{
public:
	Point(){x=0.;y=0.;z=0.;};
	// copy operator
	Point operator=(const Point pt) ;
	Point operator+(const Point pt) const;
	//Point operator-(const Point pt) const;
	Point operator*(double m) const;
	Point operator/(double m) const;
	double x,y,z;
};

Point Point::operator=(const Point pt)
{
	x = pt.x;
	y = pt.y;
	z = pt.z;
	return *this;
}
Point Point::operator+(const Point pt) const
{
	Point temp;
	temp.x = x + pt.x;
	temp.y = y + pt.y;
	temp.z = z + pt.z;
	return temp;
}
Point Point::operator*(double m) const
{
	Point temp;
	temp.x = x*m;
	temp.y = y*m;
	temp.z = z*m;
	return temp;
}
Point Point::operator/(double m) const
{
	Point temp;
	temp.x = x/m;
	temp.y = y/m;
	temp.z = z/m;
	return temp;
}