All,

This may be more of a POV question, but maybe you guys can shed some light
on this... (no pun intended)... I've been trying to get "softer" shadows in
my renders by creating a reflection dish for a point light. I've also been
playing around with "lenses" made from meshes with "interior" turned on to
make them "bend" light. I don't know much about the photons feature of POV,
but I thought it was meant to more accurately simulate reality, or the real
behavior of light refracting through glass and reflecting from mirrors. How
come when I set these things up (if I've even done so properly - see below),
they have little to no effect on how the point light lights the scene? I've
even tinkered with radiosity, but that doesn't even seem to affect the
shadows cast by the point light at all.

BTW, I know this issue has been "addressed" by "area" lights with "jittered"
shadows, or whatever the term is... but that seems so "fake" to me -
shouldn't ray-tracing be able to more accurately simulate "real-life" light
behavior? Shouldn't I be able to model the components of a real-world
spotlight and have it behave the same way? Why is this not working?

Also BTW... it would be really nice to have some basic help system for the
various settings in the radiosity and photon tabs in the Scene Settings
dialog box - maybe in the form of tool tips - to let one know generally what
the various settings are doing. They all have arcane names that are familiar
to programmers, I suppose, but for the average lay person, such as myself,
their meanings can only be guessed at. Some kind of description of each
setting built into Moray would help me know what settings I should place to
achieve the effect I'm after (ie: "When you set the ADC Bailout high it does
this, but when you set it low it does that." or some-such.) I know there is
general help on this in Moray's help (which is broken on my setup, BTW -
gives an error on my fresh install of 3.5 shareware - probably just my IE's
Java setup is bad...) on these settings tabs, but something built in to be
"live" while I'm making the adjustments would be great!

Just some thots for discussion...

-Kman

Post a reply to this message

Kman wrote:
> BTW, I know this issue has been "addressed" by "area" lights with "jittered"
> shadows, or whatever the term is... but that seems so "fake" to me -
> shouldn't ray-tracing be able to more accurately simulate "real-life" light
> behavior? Shouldn't I be able to model the components of a real-world
> spotlight and have it behave the same way? Why is this not working?

It isn't working because "real-life" lights aren't discreet points; they
are areas.  The only way to make a "real" light source in POV is to
generate an area light by hand; e.g. build an array of point lights.
Exactly the same effect, except area lights with jittered sampling
produce a smoother effect in a lot less time.

Post a reply to this message

Okay, I turned on and input a setting of 0.5 for my "caustics" setting of
the lense material and it caused the light to be bent. Its not having the
hoped-for effect on my shadows, but it is having some interesting lighting
effects on the model. (See the before and after pics in m.bin) FYI...

-Kman

"Kman" <mzu### [at] yahoocom> wrote in message
news:3f940d76@news.povray.org...
> All,
>
> This may be more of a POV question, but maybe you guys can shed some light
> on this... (no pun intended)... I've been trying to get "softer" shadows
in
> my renders by creating a reflection dish for a point light. I've also been

<snip>

> "live" while I'm making the adjustments would be great!
>
> Just some thots for discussion...
>
> -Kman
>
>

Post a reply to this message

Tim Cook wrote:
> Kman wrote:
> 
>> BTW, I know this issue has been "addressed" by "area" lights with 
>> "jittered"
>> shadows, or whatever the term is... but that seems so "fake" to me -
>> shouldn't ray-tracing be able to more accurately simulate "real-life" 
>> light
>> behavior? Shouldn't I be able to model the components of a real-world
>> spotlight and have it behave the same way? Why is this not working?
> 
> 
> It isn't working because "real-life" lights aren't discreet points; they
> are areas.  The only way to make a "real" light source in POV is to
> generate an area light by hand; e.g. build an array of point lights.
> Exactly the same effect, except area lights with jittered sampling
> produce a smoother effect in a lot less time.
> 
But Tim, what I'm after is seeing the effects of the light that has been 
reflected from the parabolic cone in which most lights are mounted. It 
is this reflective cone that most often, and certainly most effectively, 
causes "soft" shading in scenes. You've seen those silver 
umbrella-shaped light shades in professional photo studios, right? Their 
sole purpose is to "soften" the lighting in a scene. The relative size 
of the filament in a lightbulb makes it effectively a "point" anyway... 
How come POV-Ray is not registering the light that reflects off that 
reflective cone and is being "bounced" back into the scene? Isn't that 
what "ray-tracing" is supposed to be doing? If not, I would guess that 
at least radiosity should cause this to happen. (Isn't that what 
"radiosity" is defined as being? - the reflected light from other 
objects in the scene?) I guess I'm just bewildered by the way things 
work in the POV-Ray world.

-Kman

Post a reply to this message

Okay, so playing around with this lense idea gets some really cool lighting
effects, but none of these is having any effect at all on the shadows. I can
only assume that shadows are created/calculated in a different process by
POV-Ray. Does this mean that its not a true ray-trace process according to
the strictest definition of the term? I'm just learning all this stuff, but
I thought I understood ray-tracing to be a process by which every pixel or
sub-pixel on the "screen" (or picture-frame, for lack of a better
descriptive) was "traced" back to its light source, picking up color
properties along the way based on the properties of the objects and lights
in the scene. Too simplistic a description, I'm guessing. Could someone
'splain?

-Kman


"Kman" <mzu### [at] yahoocom> wrote in message
news:3f94171f$1@news.povray.org...
> Okay, I turned on and input a setting of 0.5 for my "caustics" setting of
> the lense material and it caused the light to be bent. Its not having the
> hoped-for effect on my shadows, but it is having some interesting lighting
> effects on the model. (See the before and after pics in m.bin) FYI...
>
> -Kman
>
<snip>

Post a reply to this message

Maybe you should try out the lightsys macro?

/Stefan

"Kman" <mzu### [at] toughguynet> wrote in message
news:3f94203b$1@news.povray.org...
> Tim Cook wrote:
> > Kman wrote:
> >
> >> BTW, I know this issue has been "addressed" by "area" lights with
> >> "jittered"
> >> shadows, or whatever the term is... but that seems so "fake" to me -
> >> shouldn't ray-tracing be able to more accurately simulate "real-life"
> >> light
> >> behavior? Shouldn't I be able to model the components of a real-world
> >> spotlight and have it behave the same way? Why is this not working?
> >
> >
> > It isn't working because "real-life" lights aren't discreet points; they
> > are areas.  The only way to make a "real" light source in POV is to
> > generate an area light by hand; e.g. build an array of point lights.
> > Exactly the same effect, except area lights with jittered sampling
> > produce a smoother effect in a lot less time.
> >
> But Tim, what I'm after is seeing the effects of the light that has been
> reflected from the parabolic cone in which most lights are mounted. It
> is this reflective cone that most often, and certainly most effectively,
> causes "soft" shading in scenes. You've seen those silver
> umbrella-shaped light shades in professional photo studios, right? Their
> sole purpose is to "soften" the lighting in a scene. The relative size
> of the filament in a lightbulb makes it effectively a "point" anyway...
> How come POV-Ray is not registering the light that reflects off that
> reflective cone and is being "bounced" back into the scene? Isn't that
> what "ray-tracing" is supposed to be doing? If not, I would guess that
> at least radiosity should cause this to happen. (Isn't that what
> "radiosity" is defined as being? - the reflected light from other
> objects in the scene?) I guess I'm just bewildered by the way things
> work in the POV-Ray world.
>
> -Kman
>

Post a reply to this message

[POV-Ray 2.2 What is Ray-Tracing?] explains it fairly simple.

/Stefan


"Kman" <mzu### [at] yahoocom> wrote in message
news:3f9440d5$1@news.povray.org...
> Okay, so playing around with this lense idea gets some really cool
lighting
> effects, but none of these is having any effect at all on the shadows. I
can
> only assume that shadows are created/calculated in a different process by
> POV-Ray. Does this mean that its not a true ray-trace process according to
> the strictest definition of the term? I'm just learning all this stuff,
but
> I thought I understood ray-tracing to be a process by which every pixel or
> sub-pixel on the "screen" (or picture-frame, for lack of a better
> descriptive) was "traced" back to its light source, picking up color
> properties along the way based on the properties of the objects and lights
> in the scene. Too simplistic a description, I'm guessing. Could someone
> 'splain?
>
> -Kman
>
>
> "Kman" <mzu### [at] yahoocom> wrote in message
> news:3f94171f$1@news.povray.org...
> > Okay, I turned on and input a setting of 0.5 for my "caustics" setting
of
> > the lense material and it caused the light to be bent. Its not having
the
> > hoped-for effect on my shadows, but it is having some interesting
lighting
> > effects on the model. (See the before and after pics in m.bin) FYI...
> >
> > -Kman
> >
> <snip>
>
>

Post a reply to this message