Re: TECH3D digest 38

[T3D John O. Merritt <JOMERRITT@xxxxxxxxxxx>]

John B wrote about yellow glasses and monochromatic light.  I suspect
these glasses are not monochromatic, but rather a blue cut-off
filter.  We'd have to run them through a spectrophotometer to see
how broad-band they are.  

If they are blue cut-off filters, they could improve the contrast
when looking at a distance in atmospheric haze... the haze 
scatters blue light more than red light, so by reducing the 
blue light at the retina, the contrast for the non-blue part
of the spectrum should improve.  

I haven't kept up on this area, but I recall that the visual system
is not wired for detail in the blue end of the spectrum, so by
cutting off the blue light, perhaps the detail-analyzers have
a cleaner signal?

I don't know of depth acuity (to relate this to Tech3D) deata
where spectral bandwidth is a factor, but haven't searched for it.
It might be interesting to test depth acuity at a distance in
the presence of haze, with and without minus-blue filters.

John Merritt


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