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

[Paul Chilton]

Hi Rob, Andy,

Thank you both for you suggestions. I've been concentrating on getting the
glow material to properly work first.

I've looked at the Radiance reference manual and read the description of
glow. In my rad file I've made a new glow material:

*void glow* glowsurface
0
0
4 0.898 0.898 0.898 50

and I've changed the name of the polygon that I want to glow from it's
original surface name of 'plaster_insulated' to the name specified above
i.e. 'glowsurface'. However in my image the surface appears to be black and
I've tried changing the maxrad variable but this hasn't had an effect. I've
read what it says about maxrad but I'm still unsure of what it is
exactly and what the variable range is (is it a 0-1?) and what a typical
value is.
Could you please help?

Regards,

Paul.
On Wed, May 27, 2009 at 3:08 PM, Rob Guglielmetti <rpg at rumblestrip.org>wrote:

>
> On May 26, 2009, at 8:07 PM, Paul Chilton wrote:
>
> Hi Lars, Rob
>>
>> It looks like I have managed to get the mkillum surface to work for the
>> skylight. The render times are reduced and the images displayed look
>> different too.
>>
>> However, I have been testing the use of the mkillum without the artificial
>> lighting turned on in my model. When I do turn them on and run them with the
>> parameters set to high accuracy levels, the simulation takes a very long
>> time. I think that any time gained by the mkillum surface is negated by the
>> number of lights it has to simulate.
>>
>
> The simulations will increase as you increase the number of light sources,
> that is a fact of life (or virtual life, as in this case). The mkillum
> process will help improve the speed and accuracy of the lighting simulation
> of the light filtering in from the skylight, but as you add in complexity
> through electric light sources, you will experience a delay in the
> simulation times, yes.
>
>
> Is there a way of simplifying the artificial lighting of the tenants either
>> side of the mall space? The goal of the artificial lighting in the tenancies
>> is not to be highly accurate but rather to give the daylight in the mall
>> space some context and to make it look more realistic as I’m only concerned
>> about the daylight in the mall. Ideally I would like to put a mkillum
>> surface in the position of the array of lights but I feel that this wouldn’t
>> help reduce the complexity of the simulation as the same number of
>> calculations still need to be carried out, am I right?
>>
>
> The electric lights probably aren't doing much in terms of contribution to
> the overall lighting that is predominantly from the skylight. In this case
> you can use the glow material for your lights (with a small radius, see the
> docs) to affect a visual context as you are looking for without exacting a
> huge penalty on the render time.
>
>
>> Is there a way in Radiance to make a planer object emit a certain amount
>> of uniform light?
>>
>>
> Yep, the glow is the material you want for this. I have used it
> infrequently but I believe this is exactly what you need to get these
> renderings looking good and completing in reasonable timeframes.
>
>
> - Rob Guglielmetti
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>



-- 
Paul Chilton

Renewable Energy Engineer

[m] 0400 306 791 | [e] p.chilton at gmail.com
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