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24 Sep 2021 05:39:10 EDT (-0400)
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From: Chris R
Subject: Moving indoors
Date: 5 Aug 2021 16:45:00
Message: <web.610c4d895466217c6fb991d75cc1b6e@news.povray.org>
For a change of pace, I started playing with an indoor scene.  I couldn't help
myself, however, and included a window that looks out to a sunset sky.

The scene is a low view of a pool-table near the window of a pool hall, looking
out across the street to a hardware store.  I used the brick and wood tools I
had developed earlier and discussed here in a previous post for the interior
walls of the pool hall and the exterior wall of the hardware store.

The pool table is a bit too shiny, but I like the reflection of the store across
the street.  I will share another view from a higher vantage point that shows
the asphalt road, complete with a crack that I spent way too much time on.

The ceiling of the pool hall is covered with can lights.  I originally had each
one of them be a fading light source, but since there are so many it took
forever to render with little effect on the scene.  Instead, they are now just
emitting light, and a few of them near the viewpoint are actual light sources,
as is the pool-table light above the table.

I'd like to put an awning over the hardware store, but have to play around with
cloth first.  I also want to put a neon sign on the pool hall that is partially
visible through the window.  I'm sure that will add another few hours of
reflection rendering.

-- Chris R


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From: Thomas de Groot
Subject: Re: Moving indoors
Date: 6 Aug 2021 03:21:32
Message: <610ce2fc@news.povray.org>
Nice one indeed and well done. Maybe the edge of the green felt, at the 
entrance down to the basket, is a bit too sharp? I would imagine it more 
rounded.

-- 
Thomas


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From: clipka
Subject: Re: Moving indoors
Date: 6 Aug 2021 06:50:24
Message: <610d13f0$1@news.povray.org>
Am 05.08.2021 um 22:43 schrieb Chris R:

> The pool table is a bit too shiny, but I like the reflection of the store across
> the street.

It looks to me like you're not using `fresnel`.

You should. It's more realistic, and it should also mute the reflections 
on the wood we're seeing head-on, while at the same time preserving the 
reflections on the wood we're seeing at a shallow angle.

In real life, Fresnelian reflection applies not only to transparent 
materials, but also to opaque ones (except metals - or, more 
technically, non-dielectrics - which behave somewhat different). And 
yes, such opaque materials also have an index of refraction. If you're 
unsure about the applicable value, 1.5 works reasonably well for most 
situations. The IOR of most opaque materials lies somewhere between 1.4 
and 1.6.

The same goes for the pool balls, which also look unnatural to me now 
that I've spent more time looking at them. The reflections on them 
should also appear more muted where we're seeing the surface head-on, as 
opposed to at an angle.


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From: Chris R
Subject: Re: Moving indoors
Date: 6 Aug 2021 09:15:00
Message: <web.610d34e27919aade6fb991d75cc1b6e@news.povray.org>
Thomas de Groot <tho### [at] degrootorg> wrote:
> Nice one indeed and well done. Maybe the edge of the green felt, at the
> entrance down to the basket, is a bit too sharp? I would imagine it more
> rounded.
>
> --
> Thomas

Thanks, I'll take another look at the model and see if I can fix that.

-- Chris R


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From: Chris R
Subject: Re: Moving indoors
Date: 6 Aug 2021 09:20:00
Message: <web.610d36267919aade6fb991d75cc1b6e@news.povray.org>
clipka <ano### [at] anonymousorg> wrote:
> Am 05.08.2021 um 22:43 schrieb Chris R:
>
> > The pool table is a bit too shiny, but I like the reflection of the store across
> > the street.
>
> It looks to me like you're not using `fresnel`.
>
> You should. It's more realistic, and it should also mute the reflections
> on the wood we're seeing head-on, while at the same time preserving the
> reflections on the wood we're seeing at a shallow angle.
>
> In real life, Fresnelian reflection applies not only to transparent
> materials, but also to opaque ones (except metals - or, more
> technically, non-dielectrics - which behave somewhat different). And
> yes, such opaque materials also have an index of refraction. If you're
> unsure about the applicable value, 1.5 works reasonably well for most
> situations. The IOR of most opaque materials lies somewhere between 1.4
> and 1.6.
>
> The same goes for the pool balls, which also look unnatural to me now
> that I've spent more time looking at them. The reflections on them
> should also appear more muted where we're seeing the surface head-on, as
> opposed to at an angle.

Thanks for the suggestion.  I think I have only used fresnel on transparent
surfaces before, and probably only because I copied a standard material or one
from an example.  (The window doesn't have it turned on either, because I am
just using M_Glass from textures.inc).  I'll try that out.

-- Chris R.


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From: Cousin Ricky
Subject: Re: Moving indoors
Date: 6 Aug 2021 20:48:18
Message: <610dd852@news.povray.org>
On 2021-08-06 9:16 AM (-4), Chris R wrote:
> clipka <ano### [at] anonymousorg> wrote:
>> Am 05.08.2021 um 22:43 schrieb Chris R:
>>
>>> The pool table is a bit too shiny, but I like the reflection of the store across
>>> the street.
>>
>> It looks to me like you're not using `fresnel`.
>>
>> [snip]
> 
> Thanks for the suggestion.  I think I have only used fresnel on transparent
> surfaces before, and probably only because I copied a standard material or one
> from an example.  (The window doesn't have it turned on either, because I am
> just using M_Glass from textures.inc).  I'll try that out.

Fresnel is the way to go whenever you have a non-metallic 'reflection'.
POV-Ray 3.8's finish-level Fresnel is best, but your image appears to
have been rendered with POV-Ray 3.7.

In 3.7, I use a layered texture for opaque objects.  The first layer is
opaque with no specular reflection, and the second layer is a clear rgbf
1 pigment with Fresnel reflection in the finish.  The result is
comparable to finish-level Fresnel reflection.

The attached images were rendered with POV-Ray 3.7.  I didn't have a
ready-made store front, but the sky and railings show well in the
reflections.  Notice the differences on the top surfaces of the boxes.
Here are the materials used:

// Left: constant reflection
  material
  { texture
    { pigment { red 1 }
      finish
      { reflection { 0.05 }
        specular albedo 0.05
        roughness 0.001
      }
    }
  }

// Center: reflection-level Fresnel
  material
  { texture
    { pigment { red 1 }
      finish
      { reflection { 1 fresnel } conserve_energy
        specular albedo 0.05
        roughness 0.001
      }
    }
    interior { ior 1.5 }
  }

// Right: layered texture
  material
  { texture
    { pigment { red 1 }
    }
    texture
    { pigment { rgbf 1 }
      finish
      { reflection { 1 fresnel } conserve_energy
        specular albedo 0.05
        roughness 0.001
      }
    }
    interior { ior 1.5 }
  }


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Preview of image 'fresnel37-level.jpg'
fresnel37-level.jpg


 

From: Alain Martel
Subject: Re: Moving indoors
Date: 7 Aug 2021 11:50:47
Message: <610eabd7$1@news.povray.org>

> For a change of pace, I started playing with an indoor scene.  I couldn't help
> myself, however, and included a window that looks out to a sunset sky.
> 
> The scene is a low view of a pool-table near the window of a pool hall, looking
> out across the street to a hardware store.  I used the brick and wood tools I
> had developed earlier and discussed here in a previous post for the interior
> walls of the pool hall and the exterior wall of the hardware store.
> 
> The pool table is a bit too shiny, but I like the reflection of the store across
> the street.  I will share another view from a higher vantage point that shows
> the asphalt road, complete with a crack that I spent way too much time on.
> 
> The ceiling of the pool hall is covered with can lights.  I originally had each
> one of them be a fading light source, but since there are so many it took
> forever to render with little effect on the scene.  Instead, they are now just
> emitting light, and a few of them near the viewpoint are actual light sources,
> as is the pool-table light above the table.
> 
> I'd like to put an awning over the hardware store, but have to play around with
> cloth first.  I also want to put a neon sign on the pool hall that is partially
> visible through the window.  I'm sure that will add another few hours of
> reflection rendering.
> 
> -- Chris R
> 

That pool table have been freshly repainted with high gloss paint.

As other have mentioned, you should use fresnel reflection, and, if 
using version 3.8, also use fresnel at the finish level for the highlights.
Don't forget to add an interior block to define the IOR.


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From: Chris R
Subject: Re: Moving indoors
Date: 16 Aug 2021 13:00:00
Message: <web.611a98ba7919aade6fb991d75cc1b6e@news.povray.org>
"Chris R" <car### [at] comcastnet> wrote:
> For a change of pace, I started playing with an indoor scene.  I couldn't help
> myself, however, and included a window that looks out to a sunset sky.
>
> The scene is a low view of a pool-table near the window of a pool hall, looking
> out across the street to a hardware store.  I used the brick and wood tools I
> had developed earlier and discussed here in a previous post for the interior
> walls of the pool hall and the exterior wall of the hardware store.
>
> The pool table is a bit too shiny, but I like the reflection of the store across
> the street.  I will share another view from a higher vantage point that shows
> the asphalt road, complete with a crack that I spent way too much time on.
>
> The ceiling of the pool hall is covered with can lights.  I originally had each
> one of them be a fading light source, but since there are so many it took
> forever to render with little effect on the scene.  Instead, they are now just
> emitting light, and a few of them near the viewpoint are actual light sources,
> as is the pool-table light above the table.
>
> I'd like to put an awning over the hardware store, but have to play around with
> cloth first.  I also want to put a neon sign on the pool hall that is partially
> visible through the window.  I'm sure that will add another few hours of
> reflection rendering.
>
> -- Chris R
Here is the outdoor view that includes the street.  I haven't done much to make
the sidewalks more realistic yet, and this was rendered before updating all of
the reflections to use fresnel, so it suffers from the same issues noted by
others on the first image.


-- Chris R


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From: Chris R
Subject: Re: Moving indoors
Date: 16 Aug 2021 13:00:00
Message: <web.611a99377919aade6fb991d75cc1b6e@news.povray.org>
Alain Martel <kua### [at] videotronca> wrote:
>
> > For a change of pace, I started playing with an indoor scene.  I couldn't help
> > myself, however, and included a window that looks out to a sunset sky.
> >
> > The scene is a low view of a pool-table near the window of a pool hall, looking
> > out across the street to a hardware store.  I used the brick and wood tools I
> > had developed earlier and discussed here in a previous post for the interior
> > walls of the pool hall and the exterior wall of the hardware store.
> >
> > The pool table is a bit too shiny, but I like the reflection of the store across
> > the street.  I will share another view from a higher vantage point that shows
> > the asphalt road, complete with a crack that I spent way too much time on.
> >
> > The ceiling of the pool hall is covered with can lights.  I originally had each
> > one of them be a fading light source, but since there are so many it took
> > forever to render with little effect on the scene.  Instead, they are now just
> > emitting light, and a few of them near the viewpoint are actual light sources,
> > as is the pool-table light above the table.
> >
> > I'd like to put an awning over the hardware store, but have to play around with
> > cloth first.  I also want to put a neon sign on the pool hall that is partially
> > visible through the window.  I'm sure that will add another few hours of
> > reflection rendering.
> >
> > -- Chris R
> >
>
> That pool table have been freshly repainted with high gloss paint.
>
> As other have mentioned, you should use fresnel reflection, and, if
> using version 3.8, also use fresnel at the finish level for the highlights.
> Don't forget to add an interior block to define the IOR.

This was my first crack at updating the scene to use fresnel reflections.  I'm
not entirely happy with it, so I am rerunning with some different min/max
reflection values for the pool table.  I noticed the highlights on the table
from the ceiling lights seem more pronounced now, but I'm not sure if I like
them that way.


-- Chris R


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Preview of image 'scene_1.2_2021-08-16.png'
scene_1.2_2021-08-16.png


 

From: Cousin Ricky
Subject: Re: Moving indoors
Date: 16 Aug 2021 16:28:54
Message: <611aca86$1@news.povray.org>
On 2021-08-16 12:58 PM (-4), Chris R wrote:
> 
> This was my first crack at updating the scene to use fresnel reflections.  I'm
> not entirely happy with it, so I am rerunning with some different min/max
> reflection values for the pool table.  I noticed the highlights on the table
> from the ceiling lights seem more pronounced now, but I'm not sure if I like
> them that way.

What value are you using for reflection?  It should be reflection { 1
fresnel } conserve_energy for the picture window, and close to 1 for the
balls and table, unless you want reduced gloss.

What value are you using for phong/specular?  At full gloss with an IOR
of 1.5, Fresnel reflection varies from 0.04 to 1.00, depending upon
angle of reflection.  I find that a value of specular albedo 0.05
normally works well; you can use this on the balls.  However, with much
of the table at a shallow reflection angle--85 degrees, I'm
guessing--reflection is around 0.6.  Try specular albedo 0.6 or phong
albedo 0.6 on the table, since the highlights are mostly on the top; but
if you still get strong highlights on the side of the table, you may
have to use an aoi texture with two different phong or specular values.
For the picture window, of course, you would use the minimum 0.04.

Always use the albedo keyword with phong and specular, so you can easily
align your highlight level with the reflection level, and not have to
worry about tweaking the highlights every time you change phong_size or
roughness.

The layered texture trick I posted above simulates the 3.8 improvements
in Fresnel reflection on opaque objects.  If you use this trick, use it
only for the balls and the table; do not use it for the picture window.

If you want only half gloss on the balls or table, reduce the highlight
by half, for example:

  #version 3.7;
  finish
  { reflection { 0.5 fresnel } conserve_energy
    specular albedo 0.025 // texture for balls and side of table
    specular albedo 0.3 // texture for top of table
  }

Things get much easier with POV-Ray 3.8, no layered textures necessary:

  #version 3.8;
  finish
  { fresnel 1
    reflection { 1 } conserve energy
    specular albedo 1 // works for balls, table, and window!
  }

Or, for half gloss:

  #version 3.8;
  finish
  { fresnel 0.5
    reflection { 0.5 } conserve energy
    specular albedo 0.5 // works for balls and table
  }


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