[Radiance-general] RE: Radiance-general Digest, Vol 80, Issue 3

Wed Oct 6 12:25:15 PDT 2010

Hi Thomas,

Thank you very much for your helpful response.

Regarding the gendaylit, I use the Radiance 3R9 for CYGwin. My environment variable RAYPATH is .:/opt/radiance/lib.
Do you mean I have to change the direction of the RAYPATH to execute the gendaylit command successfully?

Also I'm not sure which parameter I have to use for the -W parameter. I used -W 280 280, but maybe this is my mistake.
Can you explain me what is the meaning of these two values?

Thank you very much in advance.

Marion

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Today's Topics:

   1. gensky and gendaylit (Kerl, Marion (SCR US EXT))
   2. Re: gensky and gendaylit (Thomas Bleicher)

----------------------------------------------------------------------

Message: 1
Date: Wed, 6 Oct 2010 07:04:46 -0700
From: "Kerl, Marion (SCR US EXT)" <marion.kerl.ext at siemens.com>
Subject: [Radiance-general] gensky and gendaylit
To: <radiance-general at radiance-online.org>
Message-ID:
	<1F994EE20CC4154DBB59DDE3100F906B0474BAF9 at USNWK102MSX.ww017.siemens.net>

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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
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Message: 2
Date: Wed, 6 Oct 2010 09:32:40 -0500
From: Thomas Bleicher <tbleicher at googlemail.com>
Subject: Re: [Radiance-general] gensky and gendaylit
To: Radiance general discussion <radiance-general at radiance-online.org>
Message-ID:
	<AANLkTi=wzsdmXzrMTOwLa_xQd8ms__OAC1FtAv6LGGWc at mail.gmail.com>
Content-Type: text/plain; charset=windows-1252

Morning.

On Wed, Oct 6, 2010 at 9:04 AM, Kerl, Marion (SCR US EXT) <marion.kerl.ext at siemens.com> wrote:
> 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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