[Radiance-general] low lighting? is this normal?

[John Sutherland]

After setting up some candles in my reconstruction using georg's advice
with the candle RGB values. I used spheres with radius 0.0075 which
worked out RGB values of
 
R=16.575
G=5.240
B=0
 
For the flames light material.( The base weightings of rgb for tallow
candle flame were R 0.759 G 0.240 B 0)
 
For a tallow candle, emitting 1 candela of light. When using these
values my night renders look like this:
 
http://homepage.ntlworld.com/mark.sutherland/internaltallow-h.jpg
 
Which is not quite what I was expecting using pcond. I get the
impression my lighting values are too low? But the results aren't too
bad, so I thought I'd try to illuminating of a manuscript.
 
In this next render I moved the candle right up close to the manuscript
(its just off the bottom), but the illumination is not really enough to
shift the book out of scotopic levels.
 
http://homepage.ntlworld.com/mark.sutherland/outputbook22hrtallow-h.jpg
 
A false colour image shows they levels barely get above 1.5 lux
 
http://homepage.ntlworld.com/mark.sutherland/outputbook22hrtallow-hfalse
color.jpg
 
I thought id try a home experiment, I lit a candle in a pitch black room
and moved a book varing distances away from the candle, and there was
very little scotopic vision even at a distance of about a metre away.
When I do a render without the candles at night the falsecolour images
show very little increase in lux. Is lux a very sensitive scale? A small
tiny increase in lux real life increases the visability a lot? But pcond
's filter is not sensitive enough, and also the limitation of the
monitors contrast and lighting abilities not enough to show any
difference? So many questions!
 
The problem is that using the RGB lighting values suggested, they don't
appear to be able to illuminate the manuscript to a reasonable looking
level, even though in real life a candle could. Wheres my problem?
 
John
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