bightdata upside down?

radiance-general
1

hi
impillo

i found a strange thing about luminaire simulation:
i tried light+brightdata to map on a sphere the luminance desired (evaluated by ies2rad) , it works, i see the light on the walls and the light emitting ball...
but the STRANGE thing is that where the luminous flux is expected to be
hi (lower side of the ball),
the luminance is low...
if you look at the scene you see floor and low portion of wall that receive light BUT the ball is dark (upper luminance >lower luminance)
this is not correct.
i ll appreciate any help to solve this strange problem

to share this with others i m sending all the file involved
so, if you are interested, please copy each of them to a file with same name you
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
#################################
2
0 180 9
0 180 73

  3.9162 3.88268 3.80447 3.80447
  3.84916 3.97765 4.12291 4.27933
  4.32402 4.29609 4.30168 4.29609
  4.37989 4.42458 4.3743 4.27933
  4.20112 4.26816 4.44134 4.59777
  4.65922 4.60335 4.55307 4.69274
  4.86592 4.96089 5.05587 4.9162
  5.17318 5.82123 5.24581 4.53631
  3.99441 3.46927 2.97765 2.63687
  2.5419 2.47486 2.44134 2.44693
  2.03352 0.648045 0.368715 0.351955
  0.346369 0.335196 0.379888 0.430168
  0.49162 0.50838 0.50838 0.458101
  0.407821 0.379888 0.312849 0.268156
  0.217877 0.162011 0.122905 0.0502793
  0.0614525 0.0614525 0.0167598 0
  0 0 0 0
  0 3.9162 3.87151 3.81006
  3.86592 3.90503 4.06145 4.2067
  4.30168 4.3352 4.32402 4.36313
  4.43575 4.49162 4.47486 4.35754
  4.26257 4.32402 4.50838 4.7095
  4.86034 4.87709 4.81006 4.92737
  5.12849 5.36872 5.51397 5.48045
  5.27933 5.59218 5.64804 4.98324
  4.35754 3.7933 3.35754 2.97765
  2.65922 2.58101 2.58659 2.64246
  2.51955 1.57542 0.793296 0.407821
  0.368715 0.385475 0.396648 0.430168
  0.49162 0.547486 0.553073 0.50838
  0.463687 0.407821 0.357542 0.290503
  0.240223 0.195531 0.139665 0.0893855
  0.0614525 0.0502793 0.027933 0.0837989
  0.027933 0.0111732 0 0
  0 0 0 0
  0 0 3.9162 3.90503
  3.84358 3.84916 4.05587 4.18994
  4.26816 4.34637 4.43575 4.5419
  4.6648 4.75978 4.69832 4.56983
  4.50279 4.6257 4.85475 5.10615
  5.32402 5.38547 5.28492 5.24022
  5.4581 5.86034 6.15084 6.39665
  6.18436 5.88268 6.44693 6.49721
  5.89385 5.30168 4.75978 4.31285
  4.01117 3.7486 3.53631 3.50838
  3.69274 3.41341 1.89944 1.01676
  0.441341 0.407821 0.424581 0.424581
  0.480447 0.564246 0.631285 0.636872
  0.597765 0.519553 0.435754 0.368715
  0.312849 0.251397 0.195531 0.150838
  0.0949721 0.0614525 0.0502793 0.0446927
  0.0111732 0 0 0
  0 0 0 0
  0 0 0 3.9162
  3.94413 3.96089 4.03911 4.11173
  4.18994 4.30168 4.3743 4.49721
  4.69832 4.82682 4.77654 4.65922
  4.63128 4.75419 4.96648 5.19553
  5.46369 5.64804 5.55866 5.47486
  5.61453 5.88827 6.20112 6.50279
  6.75978 6.31844 6.30726 6.96648
  6.83799 6.1676 5.69832 5.22346
  4.87709 4.53073 4.34637 4.1676
  4.20112 4.06704 3.83799 2.18994
  1.11173 0.558659 0.458101 0.452514
  0.458101 0.49162 0.592179 0.659218
  0.692737 0.659218 0.597765 0.486034
  0.391061 0.312849 0.240223 0.201117
  0.145251 0.0949721 0.0558659 0.0446927
  0.00558659 0 0 0
  0 0 0 0
  3.9162 3.96648 4.05028 4.07821
  4.11173 4.2067 4.26257 4.43575
  4.6257 4.72626 4.68715 4.56983
  4.49162 4.58659 4.84916 5.10615
  5.34637 5.52514 5.46927 5.38547
  5.31844 5.6257 5.98324 6.34078
  6.55307 6.69274 6.14525 6.18994
  6.69832 6.62011 6.16201 5.64804
  5.17877 4.72067 4.54749 4.32961
  4.21788 4.15084 4.15642 3.94972
  2.44693 1.16201 0.569832 0.463687
  0.446927 0.458101 0.47486 0.541899
  0.625698 0.687151 0.670391 0.614525
  0.519553 0.413408 0.312849 0.251397
  0.201117 0.139665 0.0949721 0.0670391
  0.0446927 0.0111732 0 0
  0 0 0 0
  0 3.9162 3.98324 4.07263
  4.11732 4.1676 4.2514 4.36872
  4.53631 4.68156 4.68156 4.59777
  4.49721 4.54749 4.75419 4.97207
  5.15084 5.2905 5.3352 5.20112
  5.06704 5.18994 5.46927 5.75978
  6.03911 6.14525 6.30726 5.7486
  5.75978 6.31844 6.26816 5.65922
  5.11173 4.69832 4.36872 3.98883
  3.73743 3.56983 3.50838 3.7095
  3.50279 2.44693 1.17318 0.564246
  0.407821 0.413408 0.413408 0.430168
  0.486034 0.592179 0.670391 0.653631
  0.614525 0.547486 0.441341 0.335196
  0.256983 0.201117 0.139665 0.0949721
  0.0670391 0.0446927 0.0111732 0.00558659
  0 0 0 0
  0 0 3.9162 4.00559
  4.12849 4.18994 4.24581 4.31285
  4.4581 4.55307 4.60335 4.52514
  4.34637 4.31285 4.36313 4.51397
  4.69274 4.87151 4.95531 5
  4.85475 4.72626 4.78771 4.98324
  5.26257 5.49162 5.68156 5.81006
  5.26816 5.31285 5.79888 5.65363
  5.03911 4.49721 4.13408 3.75978
  3.35754 3.12849 3.0838 2.94972
  3 2.98324 2.07263 1.06145
  0.50838 0.379888 0.374302 0.368715
  0.374302 0.430168 0.52514 0.597765
  0.597765 0.558659 0.513966 0.446927
  0.346369 0.256983 0.201117 0.139665
  0.0893855 0.0670391 0.0558659 0.027933
  0 0 0 0
  0 0 0 3.9162
  4.01117 4.15084 4.24581 4.3352
  4.44693 4.5419 4.57542 4.53073
  4.39106 4.26257 4.17318 4.2067
  4.2905 4.38547 4.49162 4.58101
  4.60335 4.46369 4.36872 4.47486
  4.60894 4.68715 4.82682 4.84916
  4.81006 4.39665 4.39665 4.67598
  4.54749 3.98883 3.46369 3.03352
  2.6648 2.35196 2.10056 1.99441
  1.89385 1.95531 1.95531 1.51955
  0.748603 0.379888 0.329609 0.318436
  0.324022 0.312849 0.351955 0.407821
  0.469274 0.480447 0.469274 0.424581
  0.396648 0.307263 0.240223 0.178771
  0.139665 0.0893855 0.0614525 0.0446927
  0.00558659 0 0 0
  0 0 0 0
  3.9162 4.03911 4.1676 4.26816
  4.34078 4.44134 4.54749 4.55307
  4.43575 4.28492 4.1676 4.12291
  4.15084 4.2067 4.26257 4.32402
  4.32961 4.32402 4.1676 4.06145
  4.05587 4.13966 4.26816 4.31285
  4.23464 4.13966 3.93296 4.13408
  4.56983 4.1676 3.61453 3.07821
  2.69832 2.37989 2.08939 1.88827
  1.82682 1.77095 1.69832 1.73184
  1.11173 0.363128 0.301676 0.290503
  0.290503 0.290503 0.290503 0.346369
  0.385475 0.424581 0.446927 0.430168
  0.396648 0.335196 0.273743 0.217877
  0.173184 0.128492 0.0614525 0.0614525
  0.0335196 0.0111732 0 0
  0 0 0 0
  0
#################################
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
3 1 1 1

lampada.rad_light sphere lampada.rad.s
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
5 0.8 0.8 0.8
     0 0

bianco polygon pareti.1540
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
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
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
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
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
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
#################################

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2

pillo wrote:

i found a strange thing about luminaire simulation:
i tried light+brightdata to map on a sphere the luminance desired (evaluated
by ies2rad) , it works, i see the light on the walls and the light emitting
ball...
but the STRANGE thing is that where the luminous flux is expected to be hi
(lower side of the ball), the luminance is low...
if you look at the scene you see floor and low portion of wall that receive
light BUT the ball is dark (upper luminance >lower luminance)
this is not correct.
i ll appreciate any help to solve this strange problem

Surfaces with light output distribution data applied can indeed
look very confusing in Radiance, because they may get a surprisingly
dark look when viewed from outside their main emission direction.
You need to differentiate here between the luminous intensity of
your ball in a specific direction, and the luminance of a specific
half of that ball. What really counts is the direction from which
you look at each specific point.

Did you look at the ball from exactly below? I'm sure that you'd
see it glaringly bright from there. Since you see the lower half
of the ball darker than the upper half, I suspect that your
eye point is located approximately within the lower cutoff area
of the luminaire (in the border area of the output cone).

You're looking at the lower half of the ball in a flat angle.
Since the luminaire emits little light in horizontal direction,
you see it darker under that angle. But when looking at the
upper half, your view angle is steeper, which means that more
light is emitted in your direction from there.

To better understand the effect, just assume that the distribution
data aren't fixed in the center of the ball, but at each point
you're looking at individually. If you imagine the ball composed
of very small patches (like a disco mirror ball), where each patch
has the same distribution attached, then the result you see might
make more sense.

-schorsch

···

--
Georg Mischler -- simulations developer -- schorsch at schorsch.com
+schorsch.com+ -- lighting design tools -- http://www.schorsch.com/

3

ok, i realized my mistake!!!!
everything is OK and radiance, of course, works properly.
but i admit that it was not simple to understand where the mistake was (i just started with artificial lighting...).

thanks a lot for your help!!

pillo