🚀 go-pugleaf

In article <1ht21uINN1ui@overload.lbl.gov> wes@ux6.lbl.gov (Wes Bethel) writes:

>In article <1992Dec30.150955.18683@netnews.whoi.edu+ rsignell@crusty.er.usgs.gov (Richard P. Signell) writes:

>+Is there a way to tell isosurface to ignore missing or special
>+values in a 3D grid?  Setting missing values to zero or some
>+other value does *not* have the desired affect.

>The power of the "marching cubes" (tm) (blech) algorithm is that it
>breaks a big problem into  a bunch of little problems.  The little
>problem is to find where the surface of interest intersect the (possibly
>twisted) hexahedron that you're looking at.
>
>The absolute best you can do, using marching cubes that is, is to use 
>your judgement to provide data values where there are none.  I guess 
>you've tried some of the crusty interpolation modules which are 
>available, only to have land crop up in the middle of the ocean ;-). 

In fact, this is how I currently deal with the situation: I provide 
data values where there are none, making the data value equal to the
neighboring *good* point.  This way isosurface can't put a surface 
between the *special value* point and the *good* point.

I was hoping for something better, but thanks to the explanation about
how isosurface works, I now understand why it's a problem.

--
Rich Signell               |  rsignell@crusty.er.usgs.gov
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