[Radiance-general] How to verify an IES file ?

[Vaib]

Hi Rob,

You are right, its better to check the converted IES file, to have
confidence in what ies2rad has converted (as Thomas also pointed out). I
just did mine using ltview.pl, and it looks okay to me. Distribution looks
apparently similar to the polar diagram. I have included the image from
ltview.pl in the initial report on cloud.

Thanks for letting me know about the script.

Best regards,
Vaibhav




On 23 May 2014 02:18, Guglielmetti, Robert <Robert.Guglielmetti at nrel.gov>wrote:

>  I'm late to this party, but I'd add that Axel Jacobs recently added a
> great Perl script to Radiance called "ltview.pl" which is useful for
> sanity testing your converted ies files in native Radiance. The script is
> available here:
> https://github.com/NREL/Radiance/blob/combined/src/util/ltview.pl/
>
> ...and it's based on a thing I wrote a while back, which is documented
> here:
> http://www.rumblestrip.org/2004/05/10/ltview-a-radiance-utility/
>
> The idea was to look at the actual Radiance light source description that
> gets created by the ies2rad utility, in actual Radiance, so you are truly
> seeing what you're gonna get in a Radiance simulation. It's helpful for
> confirming orientation, distribution, and intensity (by running "trace"
> commands in the rvu window).
>
> And of course everyone else who has contributed here is spot on.
> Photometry files are not magic, they are simply formatted data that can
> contain errors in assumptions and input. The user must know how to read
> them and be able to do their own fact checking. Familiarity with luminaire
> testing methods (and there's a big difference between SSL and non-SSL
> sources) and the IES-LM-63 specification, as well as the whole light loss
> factor issue which has been discussed, are critical to getting an electric
> lighting calculation right.
>
> -rob
>
>
>
> Rob Guglielmetti
> NREL Commercial Buildings Research Group
> Golden, CO 80401
> robert.guglielmetti at nrel.gov
>
>
> -----Original Message-----
> *From: *Thomas Bleicher [tbleicher at gmail.com]
> *Sent: *Thursday, May 22, 2014 01:21 PM Mountain Standard Time
> *To: *Radiance general discussion
> *Subject: *Re: [Radiance-general] How to verify an IES file ?
>
> Vaib
>
> I also used to do a quick parallel simulation in something like Dialux
> that's specialized in artificial lighting simulations. If you feed it with
> the same input values for maintenance factor and room reflectance you
> should get a similar output as with Radiance. You need to be familiar with
> these tools though because they have some hidden or implicit options that
> you need to account for. But then, so does ies2rad, I think.
>
> Thomas
>
>
> On Thu, May 22, 2014 at 12:31 PM, Vaib <vaibhavjain.co at gmail.com> wrote:
>
>> Hi Thomas, Christopher,
>>
>> I used a similar luminaire of different make (Zumtobel Claris, Thanks!
>> Christopher), and it gave quite similar results to the initial
>> luminaire. That means that initial IES file was fine (even with Candela
>> Multiplier of 8.6). I then reduced the luminaire's brightness to 50% (as
>> Thomas suggested) by using "-m 0.5" in ies2rad. Now the simulated
>> illuminance are quite close to the measured ones.
>>
>> Though I will calculate Lamp Loss Factor using the standard method to
>> fine tune the results further. Thank you !
>>
>>  Best regards,
>>  Vaib
>>
>>
>>
>>
>> On 22 May 2014 19:09, Vaib <vaibhavjain.co at gmail.com> wrote:
>>
>>> Thanks Thomas, Christopher
>>>
>>>  I have used "ies2rad -dm -t white -m 0.85 TX4948.ies". I will now
>>> check with similar luminaire of another make, and also calculate a
>>> representative Lamp Loss Factor as Thomas suggested.
>>>
>>> Best,
>>> Vaib
>>>
>>>
>>>  On 22 May 2014 18:44, Christopher Rush <Christopher.Rush at arup.com>wrote:
>>>
>>>>   What command line syntax and options do you use with the ies2rad
>>>> command to create your radiance definition of the light fixture? It could
>>>> be an error with the particular manufacturer’s IES file, if they’ve somehow
>>>> made the IES file incorrect in the process of normalizing the IES file and
>>>> applying the 8.6 multiplier. In other cases IES files are sometimes
>>>> reported with a candela multiplier of 1.0 (instead of normalizing them
>>>> first). Can you test with another manufacturer’s IES file of similar
>>>> distribution, efficiency, and lamp type (maybe Zumtobel Claris).
>>>>
>>>>
>>>>
>>>>
>>>>
>>>> * From:* Vaib [mailto:vaibhavjain.co at gmail.com]
>>>> *Sent:* Thursday, May 22, 2014 6:04 AM
>>>> *To:* Radiance general discussion
>>>> *Subject:* [Radiance-general] How to verify an IES file ?
>>>>
>>>>
>>>>
>>>> Hello Everyone,
>>>>
>>>>
>>>>
>>>> In the following report, the simulated illuminance (artificial
>>>> lighting) is un-reasonably high than the measured illuminance. I suspect
>>>> that the issue may be in the lumen output (or candela multiplier) in the
>>>> IES file. Please have a look at the report.
>>>>
>>>>
>>>>
>>>> Artificial lighting report: http://bit.ly/1qXigtU
>>>>
>>>>
>>>>
>>>> May I request your suggestions on how this issue can be resolved ? How
>>>> much shall I reduce the Candela multiplier, if that is to be done ?
>>>>
>>>>
>>>>
>>>> Best regards,
>>>>
>>>> Vaib
>>>>
>>>>
>>>>
>>>>
>>>>
>>>>
>>>>
>>>>
>>>>
>>>> ____________________________________________________________
>>>> Electronic mail messages entering and leaving Arup  business
>>>> systems are scanned for acceptability of content and viruses
>>>>
>>>>  _______________________________________________
>>>> Radiance-general mailing list
>>>> Radiance-general at radiance-online.org
>>>> http://www.radiance-online.org/mailman/listinfo/radiance-general
>>>>
>>>>
>>>
>>
>> _______________________________________________
>> Radiance-general mailing list
>> Radiance-general at radiance-online.org
>> http://www.radiance-online.org/mailman/listinfo/radiance-general
>>
>>
>
> _______________________________________________
> Radiance-general mailing list
> Radiance-general at radiance-online.org
> http://www.radiance-online.org/mailman/listinfo/radiance-general
>
>
-------------- next part --------------
An HTML attachment was scrubbed...
URL: <http://www.radiance-online.org/pipermail/radiance-general/attachments/20140523/9ed2edb3/attachment.html>