Delaunay triangulation

Hello, I am having some problem with delaunay triangulation, actually i have the data set which was raw data and i perform delaunay triangulation on to that data

dt=DelaunayTri(x,y,z);

There were 3520 total points and when i find

e=edges(dt)

It gives total edges for 3520 points.Some how it was required to applying median filtering to that points and now when i am finding Delaunay Triangulation and

e=edges(dt)

it is only showing the edges upto 3281 points ,means 239 points are lost, is there any way out becuase doing this i am loosing the information from the data set.

[Doug Hull]

Please show the what you mean by median filtering. What was the new size of dt, x,y,z after median filtering.