Apparently the answer is no?

I am astounded that function graphics doesn't have an isosurface capability. That's like saying that 2-D graphics functions can show images but can't make contour plots. By way of comparison with direct graphics, SHADE_VOLUME is listed as pre-IDL version 4.0.

Ken

Hi Ken, Unfortunately there is no complete replacement for ISOSURFACE in function graphics. However, it is possible to do what you desire with a few extra steps. Here is an example, which you can run in any IDL installation.

====


; First, load the MRI head data into IDL.
file = FILEPATH('head.dat', SUBDIRECTORY = ['examples', 'data'])
data = READ_BINARY(file, DATA_DIMS = [80, 100, 57])

; Use Shade_Volume to get the isosurface veritces for a set contour value. In this case, 190
SHADE_VOLUME, data, 190, iso_verts, iso_conn, /VERBOSE

; Plot the original volume to setup the dataspace, using /NODATA to not show it
vol = volume(data,/nodata,aspect_ratio=1,aspect_z=1)

;Create the surface with Polygon and connectivity keyword.
p = POLYGON(REFORM(iso_verts[0,*]), REFORM(iso_verts[1,*]), $
REFORM(iso_verts[2,*]), /DATA, CONNECTIVITY=iso_conn, $
COLOR='red', CLIP=0)

I noticed a bit of an issue with this solution to the problem. Yes, it works in that a 3D volume is rendered, but the polygon is not 'locked' to the axes. For example, if one selects the axes in the plot and rotate axes in 3D space, the polygon follows the changes. However, if you accidentally select the polygon object and rotate that in 3D space, the axes do NOT move with it. It seems that the polygon is locked to the axes, but the axes are not locked to the polygon. I am wondering if there is a way around this issue, either by making selecting either object rotate both, more making the polygon object not selectable.

Best,

Kyle