Extract isosurface data from volume data

`fv = isosurface(X,Y,Z,V,isovalue)`

fv = isosurface(V,isovalue)

fvc = isosurface(...,colors)

fv = isosurface(...,'noshare')

fv = isosurface(...,'verbose')

[f,v] = isosurface(...)

[f,v,c] = isosurface(...)

isosurface(...)

`fv = isosurface(X,Y,Z,V,isovalue)`

computes
isosurface data from the volume data `V`

at the isosurface
value specified in `isovalue`

. That is, the isosurface
connects points that have the specified value much the way contour
lines connect points of equal elevation.

The arrays `X`

, `Y`

, and `Z`

represent
a Cartesian, axis-aligned grid. `V`

contains the
corresponding values at these grid points. The coordinate arrays (`X`

, `Y`

,
and `Z`

) must be monotonic and conform to the format
produced by `meshgrid`

. `V`

must
be a 3D volume array of the same size as `X`

, `Y`

,
and `Z`

.

The `struct`

`fv`

contains
the faces and vertices of the isosurface, which you can pass directly
to the `patch`

command.

`fv = isosurface(V,isovalue)`

assumes
the arrays `X`

, `Y`

, and `Z`

are
defined as `[X,Y,Z] = meshgrid(1:n,1:m,1:p)`

where ```
[m,n,p]
= size(V)
```

.

`fvc = isosurface(...,colors)`

interpolates
the array `colors`

onto the scalar field and returns
the interpolated values in the `facevertexcdata`

field
of the `fvc`

structure. The size of the `colors`

array
must be the same as `V`

. The `colors`

argument
enables you to control the color mapping of the isosurface with data
different from that used to calculate the isosurface (e.g., temperature
data superimposed on a wind current isosurface).

`fv = isosurface(...,'noshare')`

does
not create shared vertices. This is faster, but produces a larger
set of vertices.

`fv = isosurface(...,'verbose')`

prints
progress messages to the command window as the computation progresses.

`[f,v] = isosurface(...)`

or
`[f,v,c] = isosurface(...)`

returns
the faces and vertices (and `faceVertexcCData`

) in
separate arrays instead of a struct.

`isosurface(...)`

with no
output arguments, creates a patch in the current axes with the computed
faces and vertices. If no current axes exists, a new axes is created
with a 3-D view.

If there is no current axes and you call `isosurface`

without assigning
output arguments, MATLAB^{®} creates a new axes, sets it to a 3-D view, and adds lighting to the isosurface
graph.

Load the flow data set, which represents the speed profile of a submerged jet within an infinite tank. Draw the isosurface at the data value of `-3`

and prepare the isosurface for lighting by:

Recalculating the isosurface normals based on the volume data.

Setting the face and edge color.

Specifying the view.

Adding lights.

[x,y,z,v] = flow; p = patch(isosurface(x,y,z,v,-3)); isonormals(x,y,z,v,p) p.FaceColor = 'red'; p.EdgeColor = 'none'; daspect([1 1 1]) view(3); axis tight camlight lighting gouraud

Visualize the flow data, but color-code the surface to indicate magnitude along the *x*-axis. Use a sixth argument to `isosurface`

, which provides a means to overlay another data set by coloring the resulting isosurface. The `colors`

variable is a vector containing a scalar value for each vertex in the isosurface, to be portrayed with the current color map. In this case, it is one of the variables that define the surface, but it could be entirely independent. You can apply a different color scheme by changing the current figure color map.

[x,y,z,v] = flow; [faces,verts,colors] = isosurface(x,y,z,v,-3,x); patch('Vertices',verts,'Faces',faces,'FaceVertexCData',colors,... 'FaceColor','interp','EdgeColor','interp') view(30,-15) axis vis3d colormap copper

You can pass the `fv`

structure created by `isosurface`

directly
to the `patch`

command, but you
cannot pass the individual faces and vertices arrays (`f`

, `v`

)
to `patch`

without specifying property names. For
example,

patch(isosurface(X,Y,Z,V,isovalue))

or

[f,v] = isosurface(X,Y,Z,V,isovalue); patch('Faces',f,'Vertices',v)