[Radiance-general] Re: trans dashboard widget

[Andy McNeil]

Hi Chris,

This depends on the level of accuracy you need...

For blinds, in the past I've made a crude approximation using manufacturer's reported normal incidence data: http://www.hexcelscreen.com/xlscreen/index.htm
Ts = openfactor
Td = Tv - openfactor

However I've since learned that the typical measuring process does not measure the hemispherical transmission (the light exiting in all directions) but just the light exiting in the specular direction.  So light transmission is under represented, especially for lighter colored fabrics.

Way back when Rob G. had a measurement procedure to measure exiting light at many angles for diffuse glazing samples.   Greg provided a method for fitting trans to the measured data:
http://www.radiance-online.org/pipermail/radiance-general/2004-January/001415.html

If you want the manufacturer to provide test data there is a european standard that describes a blind measurement procedure for hemispherical transmission.  I don't know the standard number, but perhaps someone else on the list knows what it is?  This procedure only measures values for normal incidence though.

For the most accurate result at all incident angles you may need to abandon trans for mkillum with the new BSDF feature. 

Hope that helps.
Andy


On May 5, 2010, at 10:19 AM, Chris Humann wrote:

> Hi Andy, this is great!  Looking forward to the iPhone app.....
> 
> I'm curious how / where you and others are obtaining / calculating the input values for Trans, specifically for the transmitted specular component?  I've often found this (Tspec) a tough value to get or derive at as it's not measured for the LBNL, IDGB data base, nor by most glass and film manufactures.
> 
> Cheers,
> Chris
> Christian Humann ~ Associate
> LOISOS + UBBELOHDE
> - - - - - - - - - - - - - - - - - - - - - - - - - - - 
> 1917 Clement Avenue  Building 10A
> Alameda, CA  94501 USA
> - - - - - - - - - - - - - - - - - - - - - - - - - - - 
> 510 521 3800 VOICE
> 510 521 3820 FAX
> - - - - - - - - - - - - - - - - - - - - - - - - - - - 
> www.coolshadow.com
> 
> 
> 
> On May 3, 2010, at 11:56 AM, Andy McNeil wrote:
> 
>> Hi Thomas,
>> 
>> You're right, it should be trivial.  I tested the html file in safari and firefox over the weekend and came to the same conclusion regarding the sliders.  I used dashcode to create the widget, so next step is to see if one of the other sliders in dashcode is generic javascript and not webkit.
>> 
>> I've also received feedback that it doesn't work in OSX 10.4 which is a bummer, and probably related to the webkit sliders.
>> 
>> I'm not sure what to do about the labels.  dashcode has a nice drag and drop interface builder, and I don't remember there being many options for text but I'll look more closely tonight.  Maybe there is an easy way to make the text static that I missed (like a checkbox or something).  
>> 
>> Unfortunately my ability is currently limited by the capability dashcode (apple's IDE for dashboard widgets).  I'm not the best person to develop a web tool.   If there is someone with javascript and web development experience that is interested in adapting and enhancing the widget to a website I'd actively encourage them to do it.  My plan is continue to develop it as a dashboard widget within dashcode but to remove and avoid webkit specific components (if possible).  Hopefully avoiding webkit will allow it to function in most browsers.
>> 
>> Best,
>> Andy
>> 
>> 
>> 
>> 
>> On May 3, 2010, at 9:55 AM, Thomas Bleicher wrote:
>> 
>>> On Mon, May 3, 2010 at 2:25 PM, Jack de Valpine <jedev at visarc.com> wrote:
>>>> Hi Andy,
>>>> 
>>>> Let me know if I can help. I guess a web based would be the most widely
>>>> accessible.
>>> 
>>> I just opened the main.html file of the widget in a few browsers. It
>>> works fine on Safari (OS X) and Chrome (OS X).
>>> 
>>> Chrome on Windows 7 works but the labels are not visible (might be
>>> related to my vm-ware shared drive). These labels are crated by
>>> javascript which is unfortunately compacted and very hard to modify.
>>> They could easily be made static which would make the widget/html
>>> usable on Windows/Chrome, too.
>>> 
>>> Firefox shows the sliders as text fields. The sliders (as used) seem
>>> to be a Webkit only feature. It should be easy to translate that to a
>>> cross platform toolkit like jQuery. Dojo is already part of the mix
>>> somehow.
>>> 
>>> All in all it seems trivial to produce a stand alone javascript
>>> version of this.
>>> 
>>> Regards,
>>> Thomas
>>> 
>>> _______________________________________________
>>> 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://radiance-online.org/pipermail/radiance-general/attachments/20100506/71f2df82/attachment.htm