I've discovered some odd anomolies when trying to scale several of POV's
built-in PATTERNS (when used in a PIGMENT block).  Not a bug, really, just
undocumented(?) behavior.

There are visual differences between scaling a pattern using the recommended
FREQUENCY modifier vs. the more generic SCALE modifier.   The FREQUENCY
modifier seems to actually alter the pattern itself, whereas SCALE does
not.  I.e., SCALE preserves the visual pattern and simply makes it larger
or smaller, as would be expected. FREQUENCY, however, creates a kind of
subtle "banding" in addition to scaling (the banding looking similar to a
perturbed WOOD pattern.)

The patterns that show this are GRANITE, AGATE and BOZO (which leads me to
believe that this anomoly only shows itself in patterns which use "noise"
as a generator, and/or TURBULENCE.)

I realize there may be reasons for this behavior, perhaps in how the
patterns are generated.  But practically speaking, I prefer to use SCALE to
alter their size, as the pattern appearance is preserved.

However.... this is not a cure-all for the problem in general.  SCALE does
not seem to work at all on the RADIAL pattern, wheras FREQUENCY does.  And
conversely, FREQUENCY doesn't work on the CELLS pattern, while SCALE does!

Perhaps a few caveats could be inserted in POV's discussion of FREQUENCY, to
alert users to this behavior?

Ken

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