[Radiance-general] Comparison of values measured by sensors and calculated with Radiance

[Minki Sung]

Dear all,

A bared cylinder lamp (with 60cm length and 3.2cm diameter) is installed on
the wall and illuminance values were measured at some points and to some
directions as shown in the linked image. Unfortunately, the illuminance
values calculated with Radiance are different from measured values,
especially when the sensor is near the lamp or  the incident angles are high
(K~O).

Link image <http://iga.iis.u-tokyo.ac.jp/tmp/test.gif>

What can be supposed as the cause of the discrepancy?

rtrace command was as follow.
cat pts.pts | rtrace -I -oov -ar 128 -ad 512 -as 256 -ab 2 -ds 0.02 test.oct
> test.dat

and all the walls, floor and ceiling was covered with non-glossy black
paper. (reflectance 0.05)


Sung.
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