How can I create a three-dimensional surface from unsorted coordinates in MATLAB 7.4 (R2007a)?

I have vectors of X, Y and Z coordinates which are not sorted according to the nearest neighbor criterion. I would like to be able to create and render a surface using this data using in-built functions in MATLAB. Would this data be usable with the SURF function?

Answer 1

[MathWorks Support Team]

The function SURF expects a neat rectilinear grid to be supplied to it before it can render the surface. It is not possible to use this function directly to render a surface with unordered coordinates.

As a workaround the function TRISURF can be used to create the surface in conjunction with the DELAUNAY function. The DELAUNAY function performs the triangulation and returns a mx3 matrix "Tri" which defines each triangle used to render the surface. Each row of "Tri" defines a single triangular face by indexing into the vectors or matrices that contain the X, Y, and Z vertices. This "Tri" matrix can then be used with TRISURF to generate the surface.

The following code illustrates the use of DELAUNAY and TRISURF to generate a surface:

load seamount;

tri = delaunay(x,y);

h = trisurf(tri, x, y, z);

axis off

l = light('Position',[-50 -15 29])

set(gca,'CameraPosition',[208 -50 7687])

lighting phong

shading interp

colorbar EastOutside

axis vis3d