Isocaps are planes that are fitted to the limits of an isosurface to provide a visual context for the isosurface. Isocaps show a cross-sectional view of the interior of the isosurface for which the isocap provides an end cap.
The following two pictures illustrate the use of isocaps. The first is an isosurface without isocaps.
The second picture shows the effect of adding isocaps to the same isosurface.
Some additional applications of isocaps are shown in the following examples:
patch(isocaps(voldata,isoval),... 'FaceColor','interp',... ...'EdgeColor','none')
creates isocaps for the scalar volume data
isoval. You should create the isosurface
using the same volume data and isovalue to ensure that the edges of
the isocaps fit the isosurface.
Setting the patch
FaceColor property to
interp results in a coloring that maps the data values spanned by
the isocap to colormap entries. You can also set other patch properties to control the
effects of lighting and coloring on the isocaps.
This example illustrates how to set coloring and lighting characteristics when working with isocaps. There are five basic steps:
data = rand(12,12,12); data = smooth3(data,'box',5);
patch to create the isosurface and set coloring and lighting
properties. Reduce the
DiffuseStrength of the reflected light to compensate for the
brightness of the two light sources used to provide more uniform lighting.
Recalculate the vertex normals of the isosurface to produce
smoother lighting (
isoval = .5; h = patch(isosurface(data,isoval),... 'FaceColor','blue',... 'EdgeColor','none',... 'AmbientStrength',.2,... 'SpecularStrength',.7,... 'DiffuseStrength',.4); isonormals(data,h)
the same data and isovalue as the isosurface. Specify interpolated
coloring and select a colormap that provides better contrasting colors
with the blue isosurface than those in the default colormap (
patch(isocaps(data,isoval),... 'FaceColor','interp',... 'EdgeColor','none') colormap hsv
daspect([1,1,1]) axis tight view(3)
To add fairly uniform lighting, but still take advantage of
the ability of light sources to make visible subtle variations in
shape, this example uses two lights, one to the left and one to the
right of the camera (
Use Gouraud lighting to produce the smoothest variation of color (
camlight right camlight left