[Radiance-general] Irradiation on standing subject with Radiance

[Ruggiero Guida]

Thanks a lot Greg. It works now!

On Fri, 4 Mar 2016 at 16:26 Greg Ward <gregoryjward at gmail.com> wrote:

> 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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