[Radiance-general] an invisible glow

[alex summerfield]

Thanks Carsten 

> 
> To some extent, there is the possibility of having invisible glows. In
> my workshop contribution (available from the workshop page on
> radiance-online) there are patches to the standard Radiance version
> providing some further features. One of them is the possibility to
> assign a so called "secondary ambient material" (currently only to
> plastic, metal and trans). This was originally implemented to save
> calculation time in case of complicated mathematical textures applied to
> the object, but it can be used for other purposes, too.
> 

I was disappointed to be unable to attend that workshop. I'll check it out
on the web! And will be in touch regarding some of the other extensions you
mention.

> So, if for example you provide a blue plastic box and give a yellow glow
> material for the secondary ambient mat., you will see the blue box and
> the yellow shining on surfaces nearby stemming from the glow. (rather
> freaky, though, but - why not??)

One possible practical use would be to communicate to students the role of
diffuse inter-reflection in a space due to a particular surface - without
radically altering the perception of the space as a whole - as might happen
if you had to change the surface colour, rather than just its indirect
contribution. 

>> If I understand the original question correctly, then illum is
>> the solution.
>>

Thanks Schorsch, continuing on from Carsten's comments regarding glow vs
illum, I can confirm that these contextual elements form very large area
secondary sources and hence thought that using glow would be the correct
approach (the situation similar to the standard use of sky and ground glow).

I'm also referring to views from outside the proposed building  - interior
views are not a problem. The issue arises out of difference between the
viewer's immediate context and the building's lighting environment - and the
need to minimise any unnecessary modelling.

I have some slightly messy solutions - usually involving bits of outline
geometry like pieces of stage scenery near the viewer  - and these work well
in terms of the final results. But just thought that an invisible glow would
definitely be a better and more integrated way to go.

As a general rule i think to make visualisations more defensible some
explanatory imagery should be provided - in this case without the viewers
context to explicitly indicate what is happening.

cheers
alex

*******************************************************
A. J. Summerfield                 alex@arch.usyd.edu.au
Faculty of Architecture, University of Sydney
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Outside of a dog, a book is man's best friend.
Inside a dog, it's too dark to read.       Groucho Marx
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