[R] how to derive true surface area from `computeContour3d' (misc3d package) -- follow up

j. van den hoff veedeehjay at googlemail.com
Fri Nov 8 14:01:23 CET 2013

regarding my previous mail for this topic, I have in the meantime  
identified my misconception.

actually, `computeContour3d' returns the vertices just fine in the correct  
coordinate frame.

the misconception was caused basically by assuming that the `level'  
argument was a fractional
threshold relative to the maximum of the array. so I believed that the  
rendered cube actually
is the "outer surface" of the defined object in the example provided in  
the manpage.

I know understandt it's an absolute level and `example(computeContour3d)'  
consequently displays
some "interior" isocontour. this explains all my apparent errors.

I believe the manpage would benefit from a slight clarification that  
`level' actually is
an absolute, not a relative/fractional threshold.

apologies for the noise.


ps: it of course would still be nice, if the surface area (or a vector  
containing the individual triangle areas)
were returned to the caller as well ...

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