[Radiance-general] rtrace direction

[Vaib]

Thank you Andy and Lora for correcting me and pointing this out. Since it
was my first project I was under an impression that + sign after -i makes
it equivalent to -I. Ignorance can be dangerous in simulation.. :)
Wonderful group and spirit. Next semester I have to work much with Radiance
because it will be used in my masters thesis. So I have to start digging
deep and experiment more. Thank you again!

Vaib

On 22 April 2013 19:07, Andrew McNeil <amcneil at lbl.gov> wrote:

> Vaib,
>
> There is an important difference between the -i (lower case i) and -I
> (capital i) in rtrace.   When -i is given, rtrace will trace a ray in the
> direction given, and then will calculate the hemispherical irradiance at
> the point where the ray intersects with geometry (ignoring some material
> types).  With the -I command it calculates the hemispherical irradiance at
> the point you specify using the direction vector as a a normal for the
> imaginary surface on which irradiance is calculated.
>
> Users typically want -I, except for specialized cases.  You should make
> sure that  -i is correct for your case.
>
> Andy
>
>
>
>
> On Mon, Apr 22, 2013 at 4:44 AM, Vaib <vaibhavjain.co at gmail.com> wrote:
>
>> Thanks Lars. Actually my illuminance sensor (I already used -I switch),
>> was spatially located on a wall, with its direction towards a window Xorg
>> Yorg Zorg 0 -1 0. But out of this window there was no sky glow or source
>> defined (neither ground); only Sun source was defined. Thats why, the
>> sensor was not able to trace any ray coming from that direction (0 -1 0)
>> using rtrace, because there was no sky. But finally I understood that and
>> the issue is now resolved. Also this proved to me that there is some
>> reverse ray tracing going on. :)
>>
>> This was my command: echo '3 4 1.5 0 -1 0' | rtrace -w -as 512 -ar 512
>> -aa 0.15 -ab 2 -i+ -h sunnyScene.oct | rcalc -e
>> '$1=($1*.265+$2*.67+$3*.065)*179'
>>
>> Thanks again!
>>
>> Vaib
>>
>> PS: If you are interested to see the geometry, and sky, I have reported
>> that in my university assignment. Just see the 'last page' of this report:
>> http://tinyurl.com/d86dbo4
>>
>>
>>
>>
>>
>> Best regards,
>> Vaibhav Jain
>> www.vaibhavjain.co
>>
>>
>>
>>
>>
>> On 21 April 2013 23:56, Lars O. Grobe <grobe at gmx.net> wrote:
>>
>>> Hi Vaibhav,
>>>
>>> it is hard to tell what caused the result, as we do not know the
>>> parameters you used with rtrace. For the point to be interpreted as an
>>> irradiance sensor, which seams to be what you expect, you need the -I
>>> switch at least.
>>>
>>> Cheers, Lars.
>>>
>>> > Hello again!
>>> >
>>> > By doing some parametric analysis I got my answer. Actually my so
>>> called
>>> > photocell was facing the window, and since I had no sky distribution
>>> > (only sun defined in my sky file), thats why in the model there was no
>>> > sky environment (just like in outer Space). Hence the recieved
>>> > irradiance at that location was Zero. I think I am right now.
>>> >
>>> > Thanks!
>>> >
>>> > Best regards,
>>> > Vaibhav Jain
>>>
>>>
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>>
>>
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