[Radiance-general] Difference between climate data and Radiance data.
濱田裕章
hiroaki.mp.3 at gmail.com
Thu May 8 01:36:24 PDT 2014
Thank you for your reply.
My view file was wrong. And it was a simple mistake.
Though I should have turned a viewpoint below, I took an upswing.
I'd like to study the distribution of solar radiation.
As a result of having noticed a mistake, I could get good result as follows.
1. Got parallel view by Radiance.
2. Picked original data by pvalue.
3. Calculated solar radiation (W/m2) by (R+G+B)/3*4*0.8
The value I got was same as the value that I input in gensky command.
But I did not know why it was necessary to multiply 0.8.
Someone, please tell me.
Best regards,
Hiroaki
2014-05-03 6:07 GMT+09:00 Andrew McNeil <amcneil at lbl.gov>:
> Hiroaki,
>
> I agree with Greg that it's not clear what you're doing, but I'm assuming
> that you're using the climate data to create a sky file and then comparing
> the horizontal direct illuminance to horizontal direct calculated from
> solar angle and the climate data.
>
> Integrating over pixels of a rendering is a round about way of getting at
> illuminance. There's also potential error introduced by the pixel
> resolution of the sun in the image. To address this you should make your
> images very large (~4000x4000 pixels). Also I think you want to multiply
> the result by 4, not 16, in your rcalc command (you have to multiply by
> 4/pi to counter the effect of the black edge pixels and also multiply by pi
> as part of your hemisphere integration - pi cancels and the 4 remains).
> This plus fixing your view as Greg suggests should give agreement.
>
> You might consider instead using rtrace with -I+ (capital i) and -ab 1
> like so:
>
> rtrace -h -I+ -ab 1 -aa 0 -ad 10000 -lw 1e-5 sky.oct
>
>
> Also gendaylit is probably a better option than gensky for creating a sky
> from a weather file. Gensky will give agreement in this test, but the sky
> generated won't as valid as one generated by gendaylit.
>
> Best,
> Andy
>
>
> On Fri, May 2, 2014 at 12:39 PM, Greg Ward <gregoryjward at gmail.com> wrote:
>
>> Dear Hiroaki,
>>
>> Although I am not sure what you are attempting to match or how you are
>> doing so, but I can at least say that your view file is probably wrong.
>>
>> The "-vtl" option specifies a parallel view, when you no doubt want a
>> hemispherical projection ("-vth") in this case.
>>
>> Best,
>> -Greg
>>
>> *From: *濱田裕章 <hiroaki.mp.3 at gmail.com>
>>
>> *Subject: *[Radiance-general] Difference between climate data and
>> Radiance data.
>>
>> *Date: *April 30, 2014 12:28:19 AM PDT
>>
>>
>> Dear all,
>>
>>
>>
>> I’m going to study distribution of solar radiation in buildings in the
>> city by using GIS data.
>>
>> I’d like to match a climate data with Radiance data. But, I couldn’t get
>> the same value.
>>
>> Does anyone know the idea how to match climate data and Radiance data?
>>
>> My method is below.
>>
>> Obtain an illuminance by using Pvalue command.
>>
>> views file is below.
>>
>> rview rvu -vtl -vp 0 0 10 -vd 0 0 1 -vu 0 1 0 -vv 180 -vh 180 -vo 0.0 -va
>> 0.0
>>
>> skies file is below.
>>
>> !gensky 6 22 5:0 -B 46 -R 37.12796503 -a 43.035 -o -141.199 -m -135.0
>>
>> skyfunc glow skyglow
>>
>> 0
>>
>> 0
>>
>> 4 1.000 1.000 1.000 0
>>
>> skyglow source sky
>>
>> 0
>>
>> 0
>>
>> 4 0 0 1 180
>>
>> skyfunc glow groundglow
>>
>> 0
>>
>> 0
>>
>> 4 0 0 0 0
>>
>> groundglow source ground
>>
>> 0
>>
>> 0
>>
>> 4 0 0 -1 180
>>
>> bash file is below.
>>
>> pvalue -h -H -d t1_1.pic | total -m | rcalc -e '$1=($1+$2+$3)/3*16'>t1.dat
>>
>> The result is below.
>>
>> time ND*1 Altit*2 HD*3=R B*4 no
>> Gensky -i -u
>>
>> 4:00 0 0.278 0 7
>> 4.0464 9.4688 8.9056
>>
>> 5:00 225 9.498 37.12796503 46
>> 25.44 52.128 58.368
>>
>> 6:00 445 19.824 150.9137426 76
>> 43.12 75.744 96.752
>>
>> 7:00 588 30.608 299.3870167 82
>> 51.872 79.744 104.256
>>
>> 8:00 636 41.547 421.8169494 108
>> 82.752 112.752 137.504
>>
>> 9:00 618 52.252 488.6593632 151
>> 149.504 190.56 192.48
>>
>> 10:00 557 61.986 491.7378991 220
>> 295.04 371.04 279.04
>>
>> 11:00 519 68.96 484.3982757 264
>> 451.04 590.08 335.04
>>
>> 12:00 459 69.842 430.8843623 300
>> 534.08 694.08 380.96
>>
>> 13:00 395 63.995 355.0085362 348
>> 495.04 625.92 443.04
>>
>> 14:00 532 54.691 434.1369031 207
>> 220.48 276.96 263.04
>>
>> 15:00 397 44.127 276.411698 219
>> 176.48 236.48 279.04
>>
>> 16:00 442 33.203 242.0423097 160
>> 104.752 156.496 203.52
>>
>> 17:00 164 22.352 62.36849428 132
>> 75.744 129.504 167.52
>>
>> 18:00 35 11.887 7.209375721 62
>> 34.128 67.744 78.752
>>
>> 9:00 0 2.249 0 7
>> 3.976 9.032 8.9056
>>
>> *1: Normal direct solar radiation
>>
>> *2: Horizontal direct solar radiation
>>
>> *3: Solar altitude
>>
>> *4: Horizontal total solar radiation
>>
>>
>>
>> Best regards,
>>
>>
>>
>> Hiroaki
>>
>>
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