> Man I'm really digging PoseRay ... nifty piece of software!

   It's so useful, that I even would install Windows here if Wine didn't
exist!

> the moai, and added the fern. The clay pot is a lathe object that I'd
>  created for use in another scene, but goes well with the fern.

   Very nice, but I'm missing some radiosity... this kind of composition
seems to be crying for it.


-- 
Jaime Vives Piqueres
		
La Persistencia de la Ignorancia
http://www.ignorancia.org

Post a reply to this message

On 04/01/2011 03:58 AM, Jaime Vives Piqueres wrote:

>> Man I'm really digging PoseRay ... nifty piece of software!
>
> It's so useful, that I even would install Windows here if Wine didn't
> exist!
>
>> the moai, and added the fern. The clay pot is a lathe object that I'd
>> created for use in another scene, but goes well with the fern.
>
> Very nice, but I'm missing some radiosity... this kind of composition
> seems to be crying for it.
>
>
That's what I might end up doing because I'm not totally happy with 
certain aspects of the lighting just yet ... I tried putting the statue 
and pedestal in a light group. btw: this is supposed to be "after hours" 
lighting

Post a reply to this message

On 01/04/2011 10:26 AM, Jim Holsenback wrote:
> That's what I might end up doing because I'm not totally happy with
> certain aspects of the lighting just yet ... I tried putting the statue
> and pedestal in a light group. btw: this is supposed to be "after hours"
> lighting

I looks great to me.

-- 
Regards
     Stephen

Post a reply to this message

On 01/04/2011 2:59 AM, Robert McGregor wrote:
> FlyerX should get some sort of POVvy award or something; really cool program.
>

I can't agree more.

-- 
Regards
     Stephen

Post a reply to this message

On 04/01/2011 06:30 AM, Stephen wrote:
> On 01/04/2011 10:26 AM, Jim Holsenback wrote:
>> That's what I might end up doing because I'm not totally happy with
>> certain aspects of the lighting just yet ... I tried putting the statue
>> and pedestal in a light group. btw: this is supposed to be "after hours"
>> lighting
>
> I looks great to me.
>
Thanks, but I DO see what Jamie was getting at ... the wall behind the 
statue, and the moai/pedestal itself desperately needs some lighting work.

After reviewing the "Light Attenuation" thread in p.gen I was wondering 
if my problem was what I was doing for fade_distance when I discovered 
that my scattering box was intercepting my room fill light (doh!) I 
/really/ wanted to try to do this scene w/o radiosity and use a 3 point 
lighting scheme ... the key light being the spot on the moai, the back 
light being the light through the window firing up the scattering and 
the room fill to even things out.

As far as fade_distance ... I'm still investigating but I think the 
nugget here is what Christoph said:

"As I already mentioned, the key is not the fade_power, but the 
fade_distance. Sufficiently far away from the light source - relative to 
fade_distance (or, in other words, with sufficiently small fade_distance 
relative to the scene dimensions) - the formula gets arbitrarily close 
to 1/x2. "

I've been using:
#declare LightDist = vlength(LightPos);

as my value for fade_distance, Which is WRONG ... I want a smaller value 
for that and up the intensity of the light source to compensate ... 
@Christoph: Did I get that right?

Jim

Post a reply to this message

Jim Holsenback <jho### [at] povrayorg> wrote:

> I've been using:
> #declare LightDist = vlength(LightPos);
>
> as my value for fade_distance, Which is WRONG ... I want a smaller value
> for that and up the intensity of the light source to compensate ...
> @Christoph: Did I get that right?
>
> Jim

This is something I learned from doing the matinee scene.

What I have ended up doing, is set a relatively small fade distance (say the
size of the light itself).  I then figure out what general value I want it at a
certain distance (i.e., distance from light to your object or scene centre).
Then use the formula given in the help to back calculate the initial intensity.

For example, in my matinee scene for the projector, the distance from my
projector light to the screen is about 2400, I set the fade distance to about
4.5.  Back-calculating to get a value of 1 at the screen (calculate the
attenutaion value and take the inverse), gives an initial value of ~142,000!
This seems very high, but it works out well because of the samll fade distance.

-tgq

Post a reply to this message

On 04/01/2011 08:47 AM, Trevor G Quayle wrote:
> Jim Holsenback<jho### [at] povrayorg>  wrote:
>
>> I've been using:
>> #declare LightDist = vlength(LightPos);
>>
>> as my value for fade_distance, Which is WRONG ... I want a smaller value
>> for that and up the intensity of the light source to compensate ...
>> @Christoph: Did I get that right?
>>
>> Jim
>
> This is something I learned from doing the matinee scene.
>
> What I have ended up doing, is set a relatively small fade distance (say the
> size of the light itself).  I then figure out what general value I want it at a
> certain distance (i.e., distance from light to your object or scene centre).
> Then use the formula given in the help to back calculate the initial intensity.
>
> For example, in my matinee scene for the projector, the distance from my
> projector light to the screen is about 2400, I set the fade distance to about
> 4.5.  Back-calculating to get a value of 1 at the screen (calculate the
> attenutaion value and take the inverse), gives an initial value of ~142,000!
> This seems very high, but it works out well because of the samll fade distance.
>
> -tgq
>
Sweet ... I think I'm getting some material here for [3.4.7.9] ... also 
explains what Ive was talking about with a value of 125000 in one of his 
recent scenes. My initial response was ... WTF!!!

Cool ... another "teaching moments" :-)

Post a reply to this message

"Robert McGregor" <rob### [at] mcgregorfineartcom> schreef in bericht 
news:web.4d95306edc0638694d713cc0@news.povray.org...
>
> FlyerX should get some sort of POVvy award or something; really cool 
> program.

Absolutely right.

Thomas

Post a reply to this message

On 04/01/2011 08:47 AM, Trevor G Quayle wrote:
> Jim Holsenback<jho### [at] povrayorg>  wrote:
>
>> I've been using:
>> #declare LightDist = vlength(LightPos);
>>
>> as my value for fade_distance, Which is WRONG ... I want a smaller value
>> for that and up the intensity of the light source to compensate ...
>> @Christoph: Did I get that right?
>>
>> Jim
>
> This is something I learned from doing the matinee scene.
>
> What I have ended up doing, is set a relatively small fade distance (say the
> size of the light itself).  I then figure out what general value I want it at a
> certain distance (i.e., distance from light to your object or scene centre).
> Then use the formula given in the help to back calculate the initial intensity.
>
> For example, in my matinee scene for the projector, the distance from my
> projector light to the screen is about 2400, I set the fade distance to about
> 4.5.  Back-calculating to get a value of 1 at the screen (calculate the
> attenutaion value and take the inverse), gives an initial value of ~142,000!
> This seems very high, but it works out well because of the samll fade distance.
>
> -tgq
>

OK ... so here's what I've come up with and it seems to work.

#declare Intensity = function (LD,FD) { 1/(2/((1+(LD/FD))*(1+(LD/FD)))) };

 From your example I used LD=2400 and FD=4.5 and get 142756 and some 
change ;-) ... If I missed something feel free to set me straight as I'd 
like to include this in [3.4.7.9] along with a small narrative.

Jim

Post a reply to this message

> >
>
> OK ... so here's what I've come up with and it seems to work.
>
> #declare Intensity = function (LD,FD) { 1/(2/((1+(LD/FD))*(1+(LD/FD)))) };
>
>  From your example I used LD=2400 and FD=4.5 and get 142756 and some
> change ;-) ... If I missed something feel free to set me straight as I'd
> like to include this in [3.4.7.9] along with a small narrative.
>
> Jim

That's exactly it.  However I would maybe modify it slightly for presentation.
You can simplify by removing the double reciprocal (just invert the original
equation).  Also, this is true for fade_power of 2, I would leave fade_power as
part of it for completeness and to avoid confusion:

#declare Intensity = function (LD,FD) {pow(1+(LD/FD),FP)/2};

Also I would perhaps call it 'intensity multiplier' or similar.  If you want a
base intensity of 2, you would multiply this factor by 2, etc.

-tgq

Post a reply to this message