About Geospatial Applications, FME, Visual Studio, gvSIG, Global Mapper, Programming, LiDAR, GIS, Google Maps, SAGA GIS, Android, QGIS
//include these name spaces
using System.Drawing;
using QuadTreeLib;
//Implement the QuadTreeLib's IHasPoint interface as my own class e.g. PointItem.
class PointItem : QuadTreeLib.IHasPoint
{
private PointF _point;
private uint _seq;
public PointF Point
{
get { return _point; }
}
public uint Seq
{
get { return _seq; }
}
public PointItem(double x, double y,uint seq)
{
PointF p = new PointF((float)x, (float)y);
_point = p;
_seq = seq;
}
}
//...etc...
//Declare and initialize the PointQuadTree for storing PointItem classes
private PointQuadTree<PointItem> quadTree = null;
static void Main(string[] args)
{
//...etc...
LASReader reader = new LASReader(@"C:\Temp\myfile.las");
LASHeader header = reader.GetHeader().Copy();
//Create a rectangle encompassing the dataset bounds
System.Drawing.RectangleF lasRect = new System.Drawing.RectangleF((float)header.GetMinX(), (float)header.GetMinY(), (float)(header.GetMaxX()-header.GetMinX()),(float)(header.GetMaxY()-header.GetMinY()));
//Create the PointQuadTree class
quadTree = new PointQuadTree<PointItem>(lasRect);
//Populate the quad tree with the points from the LiDAR file
uint counter = 0;
while (reader.GetNextPoint())
{
counter++;
LASPoint lasPnt = reader.GetPoint().Copy();
PointItem p = new PointItem(lasPnt.X, lasPnt.Y, counter);
quadTree.Insert(p);
lasPnt.Dispose();
}
header.Dispose();
reader.Dispose();
//Define a query window bounds
double xlo = 0;
double xhi = 100000;
double ylo = 0;
double yhi = 200000;
//Query the quad tree and get the points within the window
ArrayList candidates = GetCandidates(xlo, ylo, xhi, yhi);
}
public ArrayList GetCandidates(double xlo, double ylo, double xhi, double yhi)
{
ArrayList candidates = new ArrayList();
RectangleF window = new RectangleF((float)xlo, (float)ylo, (float) (xhi - xlo), (float) (yhi - ylo));
//Call the PointQuadTree's Query method to find all the points within the window
List<PointItem> list = quadTree.Query(window);
for (int i = 0; i < list.Count; i++)
{
PointItem p = (PointItem) list[i];
candidates.Add(p.Seq);
}
return candidates;
}
I found this new open-source software CloudCompare for 3D point cloud and mesh processing, which comes along with a light weight viewer ccViewer. The interesting thing for LiDAR professionals is that the viewer is compiled with support for reading and displaying LiDAR LAS files. The display performance is pretty good even for large LAS files, but that's just about it for the viewer, other than some basic viewing perspectives and basic display coloring. It only has the ability to color the LiDAR points by classification or by elevation. On the other hand, the source code is available and if you have the time and the inclination, you can fork or contribute to the project and make the software work better with LiDAR LAS files.
