Glare DGI<0

radiance-general
1

Hi Pillo,
unfortunately I'm not able to give you information to solve your problem but I wanted to join your help request because I experienced the same problem.

If the program calculates glare using Chauvel formula a negative value can be possible if the result G of the formula is less than 1 as the logarithm will give a value < 0.

However I'd like to suggest an interesting paper to read about a new method to assess glare (the study is based on Radiance).
http://notendur.centrum.is/~lfi/images/Glare2k05b.pdf

Regards,
Annalisa.

hi everybody !!!!

my name is pillo. i m not new on this NG...

now i m in trouble with glare analysis, in fact it happens that DGI < 0...(daylight
scene whit perez sky and simple glass primitive)

i think it means that DGI is very low (quite 0) (uniformity of luminance
in the scene and little glare sources dimensions..) BUT i m not sure..

if anybody does know anything about .....

or he has some trick to analyze glare with radiance....

i need your help,

tanks

pillo

2

thanks for the interest in such this topic!!!!

now i just want to add some pepper to the discussion....
(or show everybody more clearly that i m a true beginner...)
you told me about glare analysis in the case of artificial lighting
but: how can you consider real photometric curves if they are not directly
visible (illum material+impostor geometriesare are not considered inthe
calculation...) when using impostor geometries?
is it correct to use brightdata+source.cal+light (instead of illum) and
to assign such definition to a surface close to the real shape of light
source considered??

thanks
pillo

PS (true email)
DGI<0 still remains a problem unsolved for me and i m happy to see that
Annalisa shares the same problem with me, i m not alone.
also the fact that findglaring on a octree or on a precalculated picture
gives different values is a problem....
also the fact that different VCP occur with same DGI is a problem (indexes
or calculations problems?)
so i m wondering if the problem is but an rtrace tag's right values choice...
(but which are the parameter involved?)
i m thinking about a convergence test for glare calculations (like Mardaljevic's
ab test)....BUT
the conclusion of my talk is that surely i m a beginner and the problem,
may be, depends ONLY on my little knowledge of glare calculations ...BUT
i'll appreciate every suggestion to solve it. (also like "read again WARD's
SUPERBOOK!")
SO let's talk about this interesting topic !(glare calculations using Radiance)

again,
pillo

3

a strange thing about glare and luminaire simulation:
(i tried light+brightdata), it works, i see the light on the walls...
but the STRANGE thing is that where the luminous flux is expected to be
hi (low side of the luminaire),
the luminance of the light geometry (a ball) is low... and vice versa....
it seems that rays are traced through the center of the ball and this means
NO GLARE EVALUATION (!)

to share this with others i m sending all the file involved in this new
problem through this email.
so, if you are interested, please copy them to a file with the same name
you find between double line of "########"
and then run.sh
what do you think about???
look the ball, loot the walls… the ball is upside!!!

again thanks,
pillo

the files:

···

#################################
run.sh
#################################
oconv lampada.rad scene.rad>tot.oct;
rpict -x 512 -y 512 -vf 1.vf tot.oct>1.pic;
falsecolor -s 500 -i 1.pic|ximage;
#################################
EOF
#################################

#################################
lampada.dat
#################################
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#################################
EOF
#################################

#################################
lampada.rad (obtained by ies2rad, may be this is the problem?)
#################################
# ies2rad -dm -o lampada.rad -i .6 -m .85
# Dimensions in meters
#< LTL NUMBER: 04660 DATE: 6-24-1999
#< PREPARED FOR: SIM-KAR LIGHTING
#< CATALOG NUMBER: VA3100
#< LUMINAIRE: FORMED ALUMINUM HOUSING, FORMED WHITE ENAMEL STEEL
#< REFLECTOR, CLEAR ACRYLIC PRISMATIC LENS.
#< LAMPS: ONE CLEAR 100W ED17 METAL HALIDE RATED AT 7800 LUMENS.
#< LER: 63.9 BASED ON A BALLAST FACTOR OF 100.0%
#< MOUNTING: SURFACE
# CIE(x,y) = (0.333300,0.333300)
# Depreciation = 100.0%
# 100 watt luminaire, lamp*ballast factor = 1

void brightdata lampada.rad_dist
5 corr lampada.dat source.cal src_phi2 src_theta
0
1 0.751565

lampada.rad_dist light lampada.rad_light
0
0
3 1 1 1

lampada.rad_light sphere lampada.rad.s
0
0
4 0 0 0 0.6
#################################
EOF
#################################

#################################
scene.rad
#################################
# xform -t 0 0 -4
# xform -t -2 -2.5 .4
# genbox bianco pareti 4 5 3

void plastic bianco
0
0
5 0.8 0.8 0.8
    0 0

bianco polygon pareti.1540
0
0
12
                  2 -2.5 -3.6
                  2 -2.5 4.4
                 -2 -2.5 4.4
                 -2 -2.5 -3.6

bianco polygon pareti.4620
0
0
12
                 -2 -2.5 4.4
                 -2 2.5 4.4
                 -2 2.5 -3.6
                 -2 -2.5 -3.6

bianco polygon pareti.2310
0
0
12
                 -2 2.5 -3.6
                  2 2.5 -3.6
                  2 -2.5 -3.6
                 -2 -2.5 -3.6

bianco polygon pareti.3267
0
0
12
                  2 2.5 -3.6
                 -2 2.5 -3.6
                 -2 2.5 4.4
                  2 2.5 4.4

bianco polygon pareti.5137
0
0
12
                  2 -2.5 4.4
                  2 -2.5 -3.6
                  2 2.5 -3.6
                  2 2.5 4.4

bianco polygon pareti.6457
0
0
12
                 -2 2.5 4.4
                 -2 -2.5 4.4
                  2 -2.5 4.4
                  2 2.5 4.4
#################################
EOF
#################################

#################################
1.vf
#################################
rview -vtv -vp -1.9 -2.4 0.5 -vd 0.616245 0.784538 0.0688659 -vu 0 0 1 -vh
90 -vv 90 -vo 0 -va 0 -vs 0 -vl 0
#################################
EOF
#################################