gensky and gendaylit

radiance-general
1

Hi everyone,

I have questions regarding the commands gensky and gendaylit:

1. I generate with 'gensky 2 5 15 -a 37.42 -o 122.4 -m 120' this
file:

        # gensky 2 5 15 -a 37.42 -o 122.4 -m 120
        # Local solar time: 14.61
        # Solar altitude and azimuth: 24.9 41.9
        # Ground ambient level: 11.7

        void light solar
        0
        0
        3 5.75e+06 5.75e+06 5.75e+06

        solar source sun
        0
        0
        4 -0.605853 -0.675230 0.420723 0.5

        void brightfunc skyfunc
        2 skybr skybright.cal
        0
        7 1 5.44e+00 1.16e+01 3.62e-01 -0.605853
-0.675230 0.420723

        Now I have some questions about the
generated parameters:
        What is the ground ambient level?
        How is the Solar altitude generated?
        What is the '2 skybr skybright.cal' in
the third part 'void brightfunc skyfunc' meaning?
        And why is the third line in every part
0??

2. When I want to call this command 'gendaylit 2 5 15 -a 37.42 -o
122.4 -m 120 -W 280 280 -g .1' I will get this error:

  C:\cygwin\opt\radiance\bin\gendaylit.exe 2 5 15 -a 37.42 -o
122.4 -m 120 -W 280 280 -g .1
      file coeff_perez.dat cannot be opened
      lect_coeff_perez does not work

      Does everyone of you know why I get this error?
Because the file gendaylit.exe is already in the folder
C:\cygwin\opt\radiance\bin\.

Thank you very much in advance.

Regards,
Marion

2

Morning.

Hi everyone,

I have questions regarding the commands gensky and gendaylit:

1. I generate with ‘gensky 2 5 15 -a 37.42 -o 122.4 -m 120’ this file:

# gensky 2 5 15 -a 37.42 -o 122.4 -m 120
# Local solar time: 14.61
# Solar altitude and azimuth: 24.9 41.9
# Ground ambient level: 11.7
[ ... ]

Now I have some questions about the generated parameters:

What is the ground ambient level?

An indication for the values of the '-av' option of rpict and rtrace.
If you wanted to use '-av' to represent the ambient light level of an
exterior scene you would set the values to something in the range of
11.7.

How is the Solar altitude generated?

The first three parameters of your gensky line are month, day and
time. You further specify the location's latitude and longitude with
'-a' and '-o'. The sun position and altitude are calculated from these
values.

What is the ‘2 skybr skybright.cal’ in the third part ‘void brightfunc
skyfunc’ meaning?

The output of gensky is basically a brightness distribution definition
for a sky dome. The brightness is defined by a function in the file
'skybright.cal'.

And why is the third line in every part 0??

That's the standard notation for Radiance materials (and other
objects). You have a base definition (like in 'solar' above) which
does not need any advanced options or parameters. Then there is
advanced definition of 'skyfunc' which adds two parameters on the
second line - that's why it starts with a '2'. I don't know if the
third line is used at all in Radiance but I expect they had plans for
it back in the days when it was defined. For now it just says '0' to
indicate that there are no further arguments on this line.

2. When I want to call this command ‘gendaylit 2 5 15 -a 37.42 -o 122.4
-m 120 -W 280 280 -g .1’ I will get this error:

C:\cygwin\opt\radiance\bin\gendaylit.exe 2 5 15 -a 37.42 -o 122.4 -m 120 -W 280 280 -g .1

file coeff_perez.dat cannot be opened
lect_coeff_perez does not work

Does everyone of you know why I get this error? Because the file
gendaylit.exe is already in the folder C:\cygwin\opt\radiance\bin\.

Do you have a file called 'C:\cygwin\opt\radiance\lib\coeff_perez.dat' ?
Do you have an environment variable called 'RAYPATH' in your Cygwin environment?
Which version of Radiance are you using?

Thomas

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On Wed, Oct 6, 2010 at 9:04 AM, Kerl, Marion (SCR US EXT) <[email protected]> wrote: