Fuzzy reflections can be acheived in the following way:

For a reflective object, define two new parameters called "blur" and another
called "samples."  Blur's default is 0.0, with a maximum of 1.0.  Samples
should be an integer number, with a default around 5 or so.
When casting a reflected ray, instead of casting one ray cast "samples" number
of rays and average their color values.  'Blur' should translate into an angle
of deviation of the extra rays from the absolute reflected path..  Where 0.0
means no deviation and 1.0 means the angles can deviate anywhere over the 180
degrees of the hemisphere surrounding the surface normal at the point of
intersection.  In order to avoid smearing and noise, a single ray should be
cast in the absolute reflected direction, and this ray's value should way more
heavily on the average than the other sample rays cast out.

Frosted glass is glass that refracts objects seen through them but in a
fuzzier way.   Use the above method.  But use the refracted direction instead
of the reflected direction and the anti-surface normal instead of the surface
normal.  Also...changes in IOR between mediums are not necesarily needed for
this to work. The results would look like transparent plastic or lampshades.

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Steve Horn

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