[Radiance-general] Irradiation on standing subject with Radiance

[Greg Ward]

This was my mistake.  I forgot to include the -I+ option on the rfluxmtx command line, which should have been:

	rfluxmtx -I+ -v -c 105 -y 1 - combined_sky.rad < samps.txt > daycoef.mtx

(I also added a "-v" above so you can see how it's calling rcontrib.)

Cheers,
-Greg

> From: Ruggiero Guida <ruggiero.guida at gmail.com>
> Subject: Re: [Radiance-general] Irradiation on standing subject with Radiance
> Date: March 4, 2016 5:24:58 AM PST
> 
> Thanks a lot for your help Greg,
> 
> Yes, my samps.txt has exactly 105 lines with point and direction.
> 
> When I run your command
> 
> rcontrib -c 105 -y 1 -I+ -f tregenza.cal -m groundglow -b tbin -bn 145 -m skyglow test.oct < samps.txt > daycoef.mtx
> 
> I get a daycoef.mtx with the correct number of elements of which only the first is not zero. Am I missing something? I have double check the sky and ground file and they are correct.
> 
> Thanks again
> Ruggiero
> 
> 
> On Thu, 3 Mar 2016 at 20:26 Greg Ward <gregoryjward at gmail.com> wrote:
> Hi Ruggiero,
> 
> As given, your command:
> 
> 	rcontrib -c 105 -I+ -f tregenza.cal -m skyglow -m groundglow test.oct < samps.txt > daycoef.mtx
> 
> does average 105 irradiance positions, taken them in sequence from samps.txt.  I assume this contains exactly 105 random sample positions & directions.
> 
> The output will not be Tregenza sky patches, because you are missing some needed options.  If you want your ground average to precede your 145 Tregenza patches in your matrix, then use the following order:
> 
> 	rcontrib -c 105 -y 1 -I+ -f tregenza.cal -m groundglow -b tbin -bn 145 -m skyglow test.oct < samps.txt > daycoef.mtx
> 
> The above process can in fact be simplified by merging your ground.rad and sky.rad files with some comments like so:
> 
> <combined_sky.rad>
> # Combined ground and sky vault for calculating cylindrical irradiance
> 
> # Start by telling rfluxmtx to generate a single coefficient for the ground:
> #@rfluxmtx h=u
> 
> void glow groundglow
> 0 0 4 .8 1.1 .8  0
> groundglow source ground
> 0 0 4 0 0 -1  180
> 
> # Now, tell rfluxmtx to generate a set of Tregenza sky patches using Y for "north/up":
> #@rfluxmtx h=t u=+Y
> 
> void glow sky_glow
> 0 0 4    1 1 1 0
> sky_glow source sky
> 0 0 4    0 0 1 180
> 
> ------------------
> Notice how I took out the actual sky distribution, which you don't need for a coefficient calculation.  (It would make no difference to the results in fact.)
> 
> Then, you can then use rfluxmtx to call oconv and rcontrib for you:
> 
> 	rfluxmtx -c 105 -y 1 - combined_sky.rad < samps.txt > daycoef.mtx
> 
> Note that the lone hyphen ("-") tells rfluxmtx to read from its standard input, and must be given as shown above.  Assuming you have just 105 positions  in samps.txt, I've specified -y 1, so that the output matrix has both its dimensions set properly.
> 
> Once you have the above matrix, you can multiply it against any sky vector to get the desired cylindrical irradiance:
> 
> 	gendaylit [options] | genskyvec | dctimestep daycoef.mtx
> 
> The above command should produce a single RGB triplet corresponding to the cylindrical irradiance with the given sky. 
> 
> Cheers,
> -Greg
> 
>> From: Ruggiero Guida <ruggiero.guida at gmail.com>
>> Subject: Re: [Radiance-general] Irradiation on standing subject with Radiance
>> Date: March 3, 2016 12:35:35 AM PST
>> 
> 
>> Hi Greg,
>> 
>> I finally managed to have a look at this problem again.
>> 
>> To begin with I was starting with a basic case: just sky and ground.
>> 
>> <sky.rad>
>> void light solar
>> 0 0 3 5.326e+06 5.326e+06 5.326e+06
>> 
>> solar source sun
>> 0 0 4 0.463565 0.022184 0.885785 0.533000
>> 
>> void brightfunc skyfunc
>> 2 skybright perezlum.cal
>> 0 10 5.802e+01 4.447e+01 -0.843574 -1.078181 11.876231 -3.091220 0.271617 0.463565 0.022184 0.885785 
>> 
>> skyfunc glow sky_glow
>> 0 0 4    1 1 1 0
>> sky_glow source sky
>> 0 0 4    0 0 1 180
>> 
>> <ground.rad>
>> skyfunc glow groundglow
>> 0 0 4 .8 1.1 .8  0
>> groundglow source ground
>> 0 0 4 0 0 -1  180
>> 
>> I then generate the scene with 
>> oconv materials.rad sky.rad ground.rad > test.oct
>> 
>> 
>> Let's suppose I want to calculate the contributions on the subject from a tregenza subdivision I would use
>> rcontrib -c 105 -I+ -f tregenza.cal -m skyglow -m groundglow test.oct < samps.txt > daycoef.mtx
>> 
>> This is my understanding of this command.
>> 
>> 1 - For each of the 105 random points
>> 2 - create a tregenza dome subdivision
>> 3 - calculate all the contributions from groundglow and skyglow and add them up (this considers the cosine between the normal of the point and the patch vector)
>> 4 - finally average all the results for the 105 points.
>> 
>> Does this make any sense? How would I obtain the actual matrix?
>> 
>> Thanks
>> Ruggiero
> 
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