[Radiance-general] calculating percentages of a given value in a .dat / .ok file

[Andrew Mcneil]

Hi Nick,

you can use rtrace's -f option to change the output format from floating
point to ascii.  (-faa)

The conversion from RGB irradiance to illuminance is:
179 * ( 0.265*R + 0.670*G + 0.065*B )

so you can use rcalc to calculate the percentage you desire like so:
rtrace ...  |  rcalc -e 'ill=($1*0.265+$2*0.670+$3*0.065)*179' -e
'$1=ill/300'

Best,
Andy



> On Wed, Mar 10, 2010 at 10:22 AM, Nick Hubof <nhubof at gmail.com> wrote:
>
>>  Hi,
>>
>> I am trying to do a similar process as below email, but with an illuminance plot.
>>
>> I would like to know the % above a lighting threshold of 300lux in an illumination grid output from radiance.
>>
>>
>>
>> My office uses Ecotect to build daylight models with 2d analysis grids (.pts). After running radiance the analysis grid is populated into a .dat file that is renamed in the Ecotect Batch to a .ok file.
>>
>> The .ok file consists of illumination data by point.
>>
>> So when I open the .ok file in a text editor the values are in exponential form, ie.. (1.501146e+000   1.570207e+000   9.277438e-001).
>>
>> When viewed in the Ecotect grid this value is 270.316 lux.
>>
>>
>>
>> Is there a way to have rtrace give me that percentage while the batch is running or at least convert the data from exponential form to ‘real’ values?
>>
>>
>>
>> Please let me know what to add to the batch, I assume it will be at the rtrace section or after in the batch:
>>
>> rtrace …rendering settings… gridtest.oct < gridtest.pts > gridtest.dat
>>
>> @RENAME gridtest3.dat gridtest3.ok
>>
>>
>>
>> Thanks,
>>
>> Nick
>>
>>
>>
>>
>>
>>
>>
>>
>>
>>
>>
>>
>>
>> From Greg Ward (*Mon Oct 20 10:12:17 PDT 2008)_*
>>
>>
>>
>> And here is one of the many possible standard Radiance tools ways:
>>
>>
>>
>> pvalue -h -H -o -b -df input.pic | rcalc -if -of -e '$1=1;$2=if(179*
>>
>> $1-THRESHOLD,1,0)' | total -if2
>>
>>
>>
>> You need to set THRESHOLD to the desired luminance value (in cd/
>>
>> m^2).  This will give you two numbers, the ratio of which is the
>>
>> percentage you seek.  If you want to do it all on the command line,
>>
>> you can add:
>>
>>
>>
>>         | rcalc -e '$1=100*$2/$1'
>>
>>
>>
>> to the end of the pipe.
>>
>>
>>
>> Best,
>>
>> -Greg
>>
>>
>>
>> >* From: "Marija Velickovic" <maricanis at gmail.com <http://www.radiance-online.org/mailman/listinfo/radiance-general>>*
>>
>> >* Date: October 20, 2008 3:42:28 AM PDT*
>>
>> >* *
>>
>> >* Hi,*
>>
>> >* *
>>
>> >* I suppose you can use some of standard Radiance tools for that, but  *
>>
>> >* here is another way we use.*
>>
>> >* *
>>
>> >* In Raddisplay http://deluminaelab.com/en/raddisplay_details.html  *
>>
>> >* program you can create falsecolor image from your original radiance  *
>>
>> >* image. If you define false color palette with 2 colors - one has  *
>>
>> >* value 0 and another value you want to use as a threshold, and open  *
>>
>> >* Statistiques dialog, you'll have  percent for each color in the  *
>>
>> >* tablle. You can also define the palette with more colors, for  *
>>
>> >* various threshold values.*
>>
>> >* *
>>
>> >* Hope this helps,*
>>
>> >* Marija*
>>
>> >* De Luminae.*
>>
>> >* *
>>
>> >* 2008/10/20 Galen Burrell <galenburrell at yahoo.com <http://www.radiance-online.org/mailman/listinfo/radiance-general>>*
>>
>> >* Hi All,*
>>
>> >* I have a radiance .pic with lux values calculated using rpict -i.   *
>>
>> >* Is there a way to calculate the percentage of the pixels that are  *
>>
>> >* at or above a specified value?*
>>
>> >* Thanks,*
>>
>> >* Galen*
>>
>> >
>>
>>
>>
>> _______________________________________________
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>> http://www.radiance-online.org/mailman/listinfo/radiance-general
>>
>>
>
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