[Radiance-general] Rendering large space with small detail (small picture now attached!)

[Paul Chilton]

Hi Rob, Lars,

Thanks for all your help and suggestions. I'll be giving them a try tomorrow
with a fresh pair of eyes. I'll let you know how I get on.

Regards,

Paul.

On Wed, May 20, 2009 at 2:09 PM, Rob Guglielmetti <rpg at rumblestrip.org>wrote:

> On May 19, 2009, at 8:09 PM, Paul Chilton wrote:
>
>> In the .rif file, I'm creating the mkillum function which I've used the
>> tutorial example is; mkillum= -av 18 18 18 -ab 0 . I then go into the .rad
>> file to find the properties and geometry of the skylight and then copy and
>> paste those values and descriptions separately into a new .rad file and save
>> it as window.rad. In the .rif file I then refer to this window.rad file by
>> specifying illum= window.rad. My interpretation of this procedure is that
>> rather than the ambient being the generator of light into the space it is
>> now the window itself which is the light source.
>>
>
> Hi Paul,
>
> So you're on your way. Lars has explained that mkillum will do the
> "bringing of the direct component closer to your scene" as I suggested. A
> couple of other pointers:
>
> You want to create impostor geometry or define your skylight apertures as
> illum sources. You do this by adding "illum=" lines to the .rif file. Let's
> say you have a skylight defined by a skylight.rad file, that describes the
> polygons that make up the skylight opening; you would remove that reference
> from the "scene=" line(s) and add an "illum=" line. You are telling rad to
> take any polygons defined in the illum= files and do a backwards raytrace
> from those polygons and out into the scene beyond. Generally this is the
> exterior environment, and as such the rays traced stand a much better chance
> of hitting the sun. The results of this raytrace operation are saved and
> applied as a data file to the polygons defining the skylight or aperture and
> that aperture becomes a light source. I would not worry about an -av value
> for your mkillum= line, but I would definitely increase the -ab value to 2
> or 3, and -ad 512.
>
> You should not do anything to the .rad files from there. rad is great; if
> you tell rad (via the illum= line(s)) which surfaces should be precalculated
> as light sources, rad will manage the creation of these secondary light
> sources as they are called and create its own separate rad files that
> substitute the precalculated illums for the calculations and/or renderings.
> Definitely look at the rad manual page for more info on this...
>
> - Rob Guglielmetti
>
>
> _______________________________________________
> Radiance-general mailing list
> Radiance-general at radiance-online.org
> http://www.radiance-online.org/mailman/listinfo/radiance-general
>



-- 
Paul Chilton

Renewable Energy Engineer

[m] 0400 306 791 | [e] p.chilton at gmail.com
-------------- next part --------------
An HTML attachment was scrubbed...
URL: http://radiance-online.org/pipermail/radiance-general/attachments/20090520/25981477/attachment.html