POV-Ray : Newsgroups : povray.general : Lighting Artifacts Help ? Server Time
25 May 2022 05:49:02 EDT (-0400)
  Lighting Artifacts Help ? (Message 1 to 8 of 8)  
From: scottb613
Subject: Lighting Artifacts Help ?
Date: 18 Jan 2022 10:25:00
Message: <web.61e6db4972d2af3e718d9114df363ea7@news.povray.org>
Hi Folks,

Been using POVray for years - mainly just to showcase my model work - I'm
certainly not an expert.

I'm using the latest POVray.

Any ideas - why I'm getting the strange lighting artifacts along the centerline
of the boiler?

Any other suggestions to improve the image - I'd greatly appreciate.


Image on Flickr
https://flic.kr/p/2mXWyTd


Regards,
Scott


Post a reply to this message

From: Alain Martel
Subject: Re: Lighting Artifacts Help ?
Date: 18 Jan 2022 11:03:38
Message: <61e6e4da$1@news.povray.org>
Le 2022-01-18 à 10:24, scottb613 a écrit :
> Hi Folks,
> 
> Been using POVray for years - mainly just to showcase my model work - I'm
> certainly not an expert.
> 
> I'm using the latest POVray.
> 
> Any ideas - why I'm getting the strange lighting artifacts along the centerline
> of the boiler?
> 
> Any other suggestions to improve the image - I'd greatly appreciate.
> 
> 
> Image on Flickr
> https://flic.kr/p/2mXWyTd
> 
> 
> Regards,
> Scott
> 
> 
> 
> 
> 
> 
Those may be some radiosity artifacts.
What are your radiosity settings, if any ?

Some times, scaling up everything by 10 can make those disappear, or 
make them smaller. In that case, it indicate rounding errors.


Post a reply to this message

From: scottb613
Subject: Re: Lighting Artifacts Help ?
Date: 18 Jan 2022 11:45:00
Message: <web.61e6ed71884f25c2718d9114df363ea7@news.povray.org>
Alain Martel <kua### [at] videotronca> wrote:
> > Hi Folks,
> >
> > Been using POVray for years - mainly just to showcase my model work - I'm
> > certainly not an expert.
> >
> > I'm using the latest POVray.
> >
> > Any ideas - why I'm getting the strange lighting artifacts along the centerline
> > of the boiler?
> >
> > Any other suggestions to improve the image - I'd greatly appreciate.
> >
> >
> > Image on Flickr
> > https://flic.kr/p/2mXWyTd
> >
> >
> > Regards,
> > Scott
> >
> >
> >
> >
> >
> >
> Those may be some radiosity artifacts.
> What are your radiosity settings, if any ?
>
> Some times, scaling up everything by 10 can make those disappear, or
> make them smaller. In that case, it indicate rounding errors.

Hi Alain,

Thanks so much for the response.

Hmm - I tried to post my POV file as a zipped attachment - I selected it but it
doesn't appear to upload it anywhere. Did same on this message.

Here is the "Lighting" block I used in the images - it's probably not correct -
I just played with values until I got something that seemed to work - LOL - much
like a chimp writing a symphony.

###################################################################################

"// adding a photon{} block to global_settings activates photon mapping.
// photons also need to be adjusted for light sources and objects.
global_settings {
  photons {
    spacing 0.01                 // specify the density of photons
    //count 100000               // alternatively use a total number of photons

    //gather min, max            // amount of photons gathered during render
[20, 100]
    //media max_steps [,factor]  // media photons
    //jitter 1.0                 // jitter phor photon rays
    //max_trace_level 5          // optional separate max_trace_level
    //adc_bailout 1/255          // see global adc_bailout
    //save_file "filename"       // save photons to file
    //load_file "filename"       // load photons from file
    //autostop 0                 // photon autostop option
    //radius 10                  // manually specified search radius
    // (---Adaptive Search Radius---)
    //steps 1
    //expand_thresholds 0.2, 40
  }
}

#default{ finish{ ambient 0 diffuse 1 }}

// radiosity (global illumination) settings
global_settings {
  radiosity {
    pretrace_start 0.08           // start pretrace at this size
    pretrace_end   0.04           // end pretrace at this size
    count 1600                     // higher -> higher quality (1..1600) [35]
    nearest_count 10              // higher -> higher quality (1..10) [5]
    error_bound 1.0               // higher -> smoother, less accurate [1.8]
    recursion_limit 3             // how much interreflections are calculated
(1..5+) [3]
    low_error_factor .5           // reduce error_bound during last pretrace
step
    gray_threshold 0.0            // increase for weakening colors (0..1) [0]
    minimum_reuse 0.015           // reuse of old radiosity samples [0.015]
    brightness 0.5                 // brightness of radiosity effects (0..1) [1]

    adc_bailout 0.01/2
    //normal on                   // take surface normals into account [off]
    //media on                    // take media into account [off]
    //save_file "file_name"       // save radiosity data
    //load_file "file_name"       // load saved radiosity data
    //always_sample off           // turn sampling in final trace off [on]
    //max_sample 1.0              // maximum brightness of samples
  }
}




// Persistence of Vision Ray Tracer Scene Description File
// File: ?.pov
// Vers: 3.6
// Desc: Basic Scene Example
// Date: mm/dd/yy
// Auth: ?
//

#version 3.6;

#include "colors.inc"

global_settings {
  assumed_gamma 3.0
}



// ----------------------------------------

light_source {
  <200,50,150>       // light's position
  color rgb 1.3       // light's color
  photons {           // photon block for a light source
    refraction on
    reflection on
  }
}



// ----------------------------------------

// ----------------------------------------

light_source {
  <-200,-50,250>       // light's position
  color rgb 1.3       // light's color
  photons {           // photon block for a light source
    refraction on
    reflection on
  }
}

// create a regular point light source
light_source {
  0*x                  // light's position (translated below)
  color rgb <1,1,1>    // light's color
  translate <25, 20, -45>
  // light_source { ...
  // put this inside a light_source to add light fading
  fade_distance 12
  fade_power 2
  shadowless

}

// create a regular point light source
light_source {
  0*x                  // light's position (translated below)
  color rgb <1,1,1>    // light's color
  translate <25, 20, 45>
  // light_source { ...
  // put this inside a light_source to add light fading
  fade_distance 11
  fade_power 2
  shadowless

}"

Regards,
Scott


Post a reply to this message


Attachments:
Download 'pov9.zip' (562 KB)

From: Alain Martel
Subject: Re: Lighting Artifacts Help ?
Date: 18 Jan 2022 23:14:45
Message: <61e79035$1@news.povray.org>
Le 2022-01-18 à 11:41, scottb613 a écrit :
> Alain Martel <kua### [at] videotronca> wrote:

>> Those may be some radiosity artifacts.
>> What are your radiosity settings, if any ?
>>
>> Some times, scaling up everything by 10 can make those disappear, or
>> make them smaller. In that case, it indicate rounding errors.
> 
> Hi Alain,
> 
> Thanks so much for the response.
> 
> Hmm - I tried to post my POV file as a zipped attachment - I selected it but it
> doesn't appear to upload it anywhere. Did same on this message.

Attachments are not allowed in this group. You can only have attachments 
in the groups that have .binaries. in their names.
For scene files as zip files, you want to use povray.binaries.scene-files
For shorter scene files, you can use povray.text.scene-files
For images, you want to use povray.binaries.images

> 
> Here is the "Lighting" block I used in the images - it's probably not correct -
> I just played with values until I got something that seemed to work - LOL - much
> like a chimp writing a symphony.
> 
> ###################################################################################
> 
> "// adding a photon{} block to global_settings activates photon mapping.
> // photons also need to be adjusted for light sources and objects.
> global_settings {
>    photons {
>      spacing 0.01                 // specify the density of photons
>      //count 100000               // alternatively use a total number of photons
> 
>      //gather min, max            // amount of photons gathered during render
> [20, 100]
>      //media max_steps [,factor]  // media photons
>      //jitter 1.0                 // jitter phor photon rays
>      //max_trace_level 5          // optional separate max_trace_level
>      //adc_bailout 1/255          // see global adc_bailout
>      //save_file "filename"       // save photons to file
>      //load_file "filename"       // load photons from file
>      //autostop 0                 // photon autostop option
>      //radius 10                  // manually specified search radius
>      // (---Adaptive Search Radius---)
>      //steps 1
>      //expand_thresholds 0.2, 40
>    }
> }
> 
> #default{ finish{ ambient 0 diffuse 1 }}
> 
> // radiosity (global illumination) settings
> global_settings {
>    radiosity {
>      pretrace_start 0.08           // start pretrace at this size
>      pretrace_end   0.04           // end pretrace at this size
>      count 1600                     // higher -> higher quality (1..1600) [35]
>      nearest_count 10              // higher -> higher quality (1..10) [5]
>      error_bound 1.0               // higher -> smoother, less accurate [1.8]
>      recursion_limit 3             // how much interreflections are calculated
> (1..5+) [3]
>      low_error_factor .5           // reduce error_bound during last pretrace
> step
>      gray_threshold 0.0            // increase for weakening colors (0..1) [0]
>      minimum_reuse 0.015           // reuse of old radiosity samples [0.015]
>      brightness 0.5                 // brightness of radiosity effects (0..1) [1]
> 
>      adc_bailout 0.01/2
>      //normal on                   // take surface normals into account [off]
>      //media on                    // take media into account [off]
>      //save_file "file_name"       // save radiosity data
>      //load_file "file_name"       // load saved radiosity data
>      //always_sample off           // turn sampling in final trace off [on]
>      //max_sample 1.0              // maximum brightness of samples
>    }
> }
> 
> 
> 
> 
> // Persistence of Vision Ray Tracer Scene Description File
> // File: ?.pov
> // Vers: 3.6
> // Desc: Basic Scene Example
> // Date: mm/dd/yy
> // Auth: ?
> //
> 
> #version 3.6;
> 
> #include "colors.inc"
> 
> global_settings {
>    assumed_gamma 3.0
> }
> 
> 
> 
> // ----------------------------------------
> 
> light_source {
>    <200,50,150>       // light's position
>    color rgb 1.3       // light's color
>    photons {           // photon block for a light source
>      refraction on
>      reflection on
>    }
> }
> 
> 
> 
> // ----------------------------------------
> 
> // ----------------------------------------
> 
> light_source {
>    <-200,-50,250>       // light's position
>    color rgb 1.3       // light's color
>    photons {           // photon block for a light source
>      refraction on
>      reflection on
>    }
> }
> 
> // create a regular point light source
> light_source {
>    0*x                  // light's position (translated below)
>    color rgb <1,1,1>    // light's color
>    translate <25, 20, -45>
>    // light_source { ...
>    // put this inside a light_source to add light fading
>    fade_distance 12
>    fade_power 2
>    shadowless
> 
> }
> 
> // create a regular point light source
> light_source {
>    0*x                  // light's position (translated below)
>    color rgb <1,1,1>    // light's color
>    translate <25, 20, 45>
>    // light_source { ...
>    // put this inside a light_source to add light fading
>    fade_distance 11
>    fade_power 2
>    shadowless
> 
> }"
> 
> Regards,
> Scott
> 
> 

Unless your scene contains reflective surfaces or transparent objects 
with an ior, you don't need the photons block.
Not an issue. If there are no object with a photons block that set it as 
a target, then, there will be no photons shooting.

You want to reduce pretrace_end. The default value that you use is to 
large when the resolution is larger than 800 by 600.
Good value can be 0.01 down to 0.0025. In larger renders, it may be 
preferable to go even lower.

You probably don't need a count of 1600. You could probably reduce that 
to 400 to 500.

As this is an exterior scene, a recursion_limit of 1 is probably enough. 
In some cases, a value of 2 may be needed. 3 is overkill.

You may want to reduce low_error_factor to something in the 0.2 to 0.3 
range.

You very probably need to reduce minimum_reuse. You may need to reduce 
it down to 0.005. Just make it slightly smaller that your pretrace_end.

brightness should remain at it's default value of 1. Better not use it 
at all.

You probably don't need to set adc_bailout and use the default value.

error_bound could benefit from a smaller value. Values of 1 ti 1.8 are 
OK when using regular lights as your main illumination. You usually need 
it to be less than 0.5 when you use emissive object(s) as light sources.


Note about the photons block for the light_source. That block is never 
needed UNLESS you want to prevent that light from shooting photons.
All non-shadowless lights always shoot photons at all target objects in 
any photons scene.
That block was required way back in version 3.3. It's no longer needed 
since version 3.5.
Now, the block :
   photons { refraction on reflection on }
is the default for all lights *unless* they are shadowless.

When using fading lights, it's better to set fade_distance to 1 and 
increase the light's intensity as needed.

light_source{ <25, 20, 45> // create directly at the desired location
	rgb 121 // color keyword is never needed when rgb is used
		// float value get promoted to a full rgb vector
		// the intensity is not limited to the 0..1 range
		// it can get larger than 10 000 000
	fade_distance 1
	fade_power 2
	}

Fading lights often don't play well with the shadowless attribute.
shadowless lights never cause any highlight and never shoot any photon.
Most of the time, you don't need them.
They may cause some issue when used in a radiosity scene.


Post a reply to this message

From: scottb613
Subject: Re: Lighting Artifacts Help ?
Date: 19 Jan 2022 10:50:00
Message: <web.61e832e5884f25c2718d9114df363ea7@news.povray.org>
Alain Martel <kua### [at] videotronca> wrote:

> > Alain Martel <kua### [at] videotronca> wrote:
>
> >> Those may be some radiosity artifacts.
> >> What are your radiosity settings, if any ?
> >>
> >> Some times, scaling up everything by 10 can make those disappear, or
> >> make them smaller. In that case, it indicate rounding errors.
> >
> > Hi Alain,
> >
> > Thanks so much for the response.
> >
> > Hmm - I tried to post my POV file as a zipped attachment - I selected it but it
> > doesn't appear to upload it anywhere. Did same on this message.
>
> Attachments are not allowed in this group. You can only have attachments
> in the groups that have .binaries. in their names.
> For scene files as zip files, you want to use povray.binaries.scene-files
> For shorter scene files, you can use povray.text.scene-files
> For images, you want to use povray.binaries.images
>
> >
> > Here is the "Lighting" block I used in the images - it's probably not correct -
> > I just played with values until I got something that seemed to work - LOL - much
> > like a chimp writing a symphony.
> >
> >
###################################################################################
> >
> > "// adding a photon{} block to global_settings activates photon mapping.
> > // photons also need to be adjusted for light sources and objects.
> > global_settings {
> >    photons {
> >      spacing 0.01                 // specify the density of photons
> >      //count 100000               // alternatively use a total number of photons
> >
> >      //gather min, max            // amount of photons gathered during render
> > [20, 100]
> >      //media max_steps [,factor]  // media photons
> >      //jitter 1.0                 // jitter phor photon rays
> >      //max_trace_level 5          // optional separate max_trace_level
> >      //adc_bailout 1/255          // see global adc_bailout
> >      //save_file "filename"       // save photons to file
> >      //load_file "filename"       // load photons from file
> >      //autostop 0                 // photon autostop option
> >      //radius 10                  // manually specified search radius
> >      // (---Adaptive Search Radius---)
> >      //steps 1
> >      //expand_thresholds 0.2, 40
> >    }
> > }
> >
> > #default{ finish{ ambient 0 diffuse 1 }}
> >
> > // radiosity (global illumination) settings
> > global_settings {
> >    radiosity {
> >      pretrace_start 0.08           // start pretrace at this size
> >      pretrace_end   0.04           // end pretrace at this size
> >      count 1600                     // higher -> higher quality (1..1600) [35]
> >      nearest_count 10              // higher -> higher quality (1..10) [5]
> >      error_bound 1.0               // higher -> smoother, less accurate [1.8]
> >      recursion_limit 3             // how much interreflections are calculated
> > (1..5+) [3]
> >      low_error_factor .5           // reduce error_bound during last pretrace
> > step
> >      gray_threshold 0.0            // increase for weakening colors (0..1) [0]
> >      minimum_reuse 0.015           // reuse of old radiosity samples [0.015]
> >      brightness 0.5                 // brightness of radiosity effects (0..1) [1]
> >
> >      adc_bailout 0.01/2
> >      //normal on                   // take surface normals into account [off]
> >      //media on                    // take media into account [off]
> >      //save_file "file_name"       // save radiosity data
> >      //load_file "file_name"       // load saved radiosity data
> >      //always_sample off           // turn sampling in final trace off [on]
> >      //max_sample 1.0              // maximum brightness of samples
> >    }
> > }
> >
> >
> >
> >
> > // Persistence of Vision Ray Tracer Scene Description File
> > // File: ?.pov
> > // Vers: 3.6
> > // Desc: Basic Scene Example
> > // Date: mm/dd/yy
> > // Auth: ?
> > //
> >
> > #version 3.6;
> >
> > #include "colors.inc"
> >
> > global_settings {
> >    assumed_gamma 3.0
> > }
> >
> >
> >
> > // ----------------------------------------
> >
> > light_source {
> >    <200,50,150>       // light's position
> >    color rgb 1.3       // light's color
> >    photons {           // photon block for a light source
> >      refraction on
> >      reflection on
> >    }
> > }
> >
> >
> >
> > // ----------------------------------------
> >
> > // ----------------------------------------
> >
> > light_source {
> >    <-200,-50,250>       // light's position
> >    color rgb 1.3       // light's color
> >    photons {           // photon block for a light source
> >      refraction on
> >      reflection on
> >    }
> > }
> >
> > // create a regular point light source
> > light_source {
> >    0*x                  // light's position (translated below)
> >    color rgb <1,1,1>    // light's color
> >    translate <25, 20, -45>
> >    // light_source { ...
> >    // put this inside a light_source to add light fading
> >    fade_distance 12
> >    fade_power 2
> >    shadowless
> >
> > }
> >
> > // create a regular point light source
> > light_source {
> >    0*x                  // light's position (translated below)
> >    color rgb <1,1,1>    // light's color
> >    translate <25, 20, 45>
> >    // light_source { ...
> >    // put this inside a light_source to add light fading
> >    fade_distance 11
> >    fade_power 2
> >    shadowless
> >
> > }"
> >
> > Regards,
> > Scott
> >
> >
>
> Unless your scene contains reflective surfaces or transparent objects
> with an ior, you don't need the photons block.
> Not an issue. If there are no object with a photons block that set it as
> a target, then, there will be no photons shooting.
>
> You want to reduce pretrace_end. The default value that you use is to
> large when the resolution is larger than 800 by 600.
> Good value can be 0.01 down to 0.0025. In larger renders, it may be
> preferable to go even lower.
>
> You probably don't need a count of 1600. You could probably reduce that
> to 400 to 500.
>
> As this is an exterior scene, a recursion_limit of 1 is probably enough.
> In some cases, a value of 2 may be needed. 3 is overkill.
>
> You may want to reduce low_error_factor to something in the 0.2 to 0.3
> range.
>
> You very probably need to reduce minimum_reuse. You may need to reduce
> it down to 0.005. Just make it slightly smaller that your pretrace_end.
>
> brightness should remain at it's default value of 1. Better not use it
> at all.
>
> You probably don't need to set adc_bailout and use the default value.
>
> error_bound could benefit from a smaller value. Values of 1 ti 1.8 are
> OK when using regular lights as your main illumination. You usually need
> it to be less than 0.5 when you use emissive object(s) as light sources.
>
>
> Note about the photons block for the light_source. That block is never
> needed UNLESS you want to prevent that light from shooting photons.
> All non-shadowless lights always shoot photons at all target objects in
> any photons scene.
> That block was required way back in version 3.3. It's no longer needed
> since version 3.5.
> Now, the block :
>    photons { refraction on reflection on }
> is the default for all lights *unless* they are shadowless.
>
> When using fading lights, it's better to set fade_distance to 1 and
> increase the light's intensity as needed.
>
> light_source{ <25, 20, 45> // create directly at the desired location
>  rgb 121 // color keyword is never needed when rgb is used
>   // float value get promoted to a full rgb vector
>   // the intensity is not limited to the 0..1 range
>   // it can get larger than 10 000 000
>  fade_distance 1
>  fade_power 2
>  }
>
> Fading lights often don't play well with the shadowless attribute.
> shadowless lights never cause any highlight and never shoot any photon.
> Most of the time, you don't need them.
> They may cause some issue when used in a radiosity scene.

Hi Alain,

Thanks so very much for detailed response - greatly appreciated.

I did try scaling the shapes to x10 as you suggested and it was a big
improvement.

You've given me plenty to think about and try - I'll be referring back to this
as I try your other suggested changes. Perhaps it's time to delve a bit deeper
and get out of my comfort zone.

Have a good day.

Regards,
Scott


Post a reply to this message

From: Cousin Ricky
Subject: Re: Lighting Artifacts Help ?
Date: 19 Jan 2022 15:41:23
Message: <61e87773$1@news.povray.org>
On 2022-01-19 00:14 (-4), Alain Martel wrote:
> 
> That block was required way back in version 3.3. It's no longer needed
> since version 3.5.

This is the second time I've seen you mention POV-Ray 3.3, but this
version is not in the FTP archive?  Where does one find this?


Post a reply to this message

From: scottb613
Subject: Re: Lighting Artifacts Help ?
Date: 20 Jan 2022 01:55:00
Message: <web.61e9070a884f25c2718d9114df363ea7@news.povray.org>
"scottb613" <nomail@nomail> wrote:
> Alain Martel <kua### [at] videotronca> wrote:
>
> > > Alain Martel <kua### [at] videotronca> wrote:
> >
> > >> Those may be some radiosity artifacts.
> > >> What are your radiosity settings, if any ?
> > >>
> > >> Some times, scaling up everything by 10 can make those disappear, or
> > >> make them smaller. In that case, it indicate rounding errors.
> > >
> > > Hi Alain,
> > >
> > > Thanks so much for the response.
> > >
> > > Hmm - I tried to post my POV file as a zipped attachment - I selected it but it
> > > doesn't appear to upload it anywhere. Did same on this message.
> >
> > Attachments are not allowed in this group. You can only have attachments
> > in the groups that have .binaries. in their names.
> > For scene files as zip files, you want to use povray.binaries.scene-files
> > For shorter scene files, you can use povray.text.scene-files
> > For images, you want to use povray.binaries.images
> >
> > >
> > > Here is the "Lighting" block I used in the images - it's probably not correct -
> > > I just played with values until I got something that seemed to work - LOL - much
> > > like a chimp writing a symphony.
> > >
> > >
###################################################################################
> > >
> > > "// adding a photon{} block to global_settings activates photon mapping.
> > > // photons also need to be adjusted for light sources and objects.
> > > global_settings {
> > >    photons {
> > >      spacing 0.01                 // specify the density of photons
> > >      //count 100000               // alternatively use a total number of photons
> > >
> > >      //gather min, max            // amount of photons gathered during render
> > > [20, 100]
> > >      //media max_steps [,factor]  // media photons
> > >      //jitter 1.0                 // jitter phor photon rays
> > >      //max_trace_level 5          // optional separate max_trace_level
> > >      //adc_bailout 1/255          // see global adc_bailout
> > >      //save_file "filename"       // save photons to file
> > >      //load_file "filename"       // load photons from file
> > >      //autostop 0                 // photon autostop option
> > >      //radius 10                  // manually specified search radius
> > >      // (---Adaptive Search Radius---)
> > >      //steps 1
> > >      //expand_thresholds 0.2, 40
> > >    }
> > > }
> > >
> > > #default{ finish{ ambient 0 diffuse 1 }}
> > >
> > > // radiosity (global illumination) settings
> > > global_settings {
> > >    radiosity {
> > >      pretrace_start 0.08           // start pretrace at this size
> > >      pretrace_end   0.04           // end pretrace at this size
> > >      count 1600                     // higher -> higher quality (1..1600) [35]
> > >      nearest_count 10              // higher -> higher quality (1..10) [5]
> > >      error_bound 1.0               // higher -> smoother, less accurate [1.8]
> > >      recursion_limit 3             // how much interreflections are calculated
> > > (1..5+) [3]
> > >      low_error_factor .5           // reduce error_bound during last pretrace
> > > step
> > >      gray_threshold 0.0            // increase for weakening colors (0..1) [0]
> > >      minimum_reuse 0.015           // reuse of old radiosity samples [0.015]
> > >      brightness 0.5                 // brightness of radiosity effects (0..1)
[1]
> > >
> > >      adc_bailout 0.01/2
> > >      //normal on                   // take surface normals into account [off]
> > >      //media on                    // take media into account [off]
> > >      //save_file "file_name"       // save radiosity data
> > >      //load_file "file_name"       // load saved radiosity data
> > >      //always_sample off           // turn sampling in final trace off [on]
> > >      //max_sample 1.0              // maximum brightness of samples
> > >    }
> > > }
> > >
> > >
> > >
> > >
> > > // Persistence of Vision Ray Tracer Scene Description File
> > > // File: ?.pov
> > > // Vers: 3.6
> > > // Desc: Basic Scene Example
> > > // Date: mm/dd/yy
> > > // Auth: ?
> > > //
> > >
> > > #version 3.6;
> > >
> > > #include "colors.inc"
> > >
> > > global_settings {
> > >    assumed_gamma 3.0
> > > }
> > >
> > >
> > >
> > > // ----------------------------------------
> > >
> > > light_source {
> > >    <200,50,150>       // light's position
> > >    color rgb 1.3       // light's color
> > >    photons {           // photon block for a light source
> > >      refraction on
> > >      reflection on
> > >    }
> > > }
> > >
> > >
> > >
> > > // ----------------------------------------
> > >
> > > // ----------------------------------------
> > >
> > > light_source {
> > >    <-200,-50,250>       // light's position
> > >    color rgb 1.3       // light's color
> > >    photons {           // photon block for a light source
> > >      refraction on
> > >      reflection on
> > >    }
> > > }
> > >
> > > // create a regular point light source
> > > light_source {
> > >    0*x                  // light's position (translated below)
> > >    color rgb <1,1,1>    // light's color
> > >    translate <25, 20, -45>
> > >    // light_source { ...
> > >    // put this inside a light_source to add light fading
> > >    fade_distance 12
> > >    fade_power 2
> > >    shadowless
> > >
> > > }
> > >
> > > // create a regular point light source
> > > light_source {
> > >    0*x                  // light's position (translated below)
> > >    color rgb <1,1,1>    // light's color
> > >    translate <25, 20, 45>
> > >    // light_source { ...
> > >    // put this inside a light_source to add light fading
> > >    fade_distance 11
> > >    fade_power 2
> > >    shadowless
> > >
> > > }"
> > >
> > > Regards,
> > > Scott
> > >
> > >
> >
> > Unless your scene contains reflective surfaces or transparent objects
> > with an ior, you don't need the photons block.
> > Not an issue. If there are no object with a photons block that set it as
> > a target, then, there will be no photons shooting.
> >
> > You want to reduce pretrace_end. The default value that you use is to
> > large when the resolution is larger than 800 by 600.
> > Good value can be 0.01 down to 0.0025. In larger renders, it may be
> > preferable to go even lower.
> >
> > You probably don't need a count of 1600. You could probably reduce that
> > to 400 to 500.
> >
> > As this is an exterior scene, a recursion_limit of 1 is probably enough.
> > In some cases, a value of 2 may be needed. 3 is overkill.
> >
> > You may want to reduce low_error_factor to something in the 0.2 to 0.3
> > range.
> >
> > You very probably need to reduce minimum_reuse. You may need to reduce
> > it down to 0.005. Just make it slightly smaller that your pretrace_end.
> >
> > brightness should remain at it's default value of 1. Better not use it
> > at all.
> >
> > You probably don't need to set adc_bailout and use the default value.
> >
> > error_bound could benefit from a smaller value. Values of 1 ti 1.8 are
> > OK when using regular lights as your main illumination. You usually need
> > it to be less than 0.5 when you use emissive object(s) as light sources.
> >
> >
> > Note about the photons block for the light_source. That block is never
> > needed UNLESS you want to prevent that light from shooting photons.
> > All non-shadowless lights always shoot photons at all target objects in
> > any photons scene.
> > That block was required way back in version 3.3. It's no longer needed
> > since version 3.5.
> > Now, the block :
> >    photons { refraction on reflection on }
> > is the default for all lights *unless* they are shadowless.
> >
> > When using fading lights, it's better to set fade_distance to 1 and
> > increase the light's intensity as needed.
> >
> > light_source{ <25, 20, 45> // create directly at the desired location
> >  rgb 121 // color keyword is never needed when rgb is used
> >   // float value get promoted to a full rgb vector
> >   // the intensity is not limited to the 0..1 range
> >   // it can get larger than 10 000 000
> >  fade_distance 1
> >  fade_power 2
> >  }
> >
> > Fading lights often don't play well with the shadowless attribute.
> > shadowless lights never cause any highlight and never shoot any photon.
> > Most of the time, you don't need them.
> > They may cause some issue when used in a radiosity scene.
>
> Hi Alain,
>
> Thanks so very much for detailed response - greatly appreciated.
>
> I did try scaling the shapes to x10 as you suggested and it was a big
> improvement.
>
> You've given me plenty to think about and try - I'll be referring back to this
> as I try your other suggested changes. Perhaps it's time to delve a bit deeper
> and get out of my comfort zone.
>
> Have a good day.
>
> Regards,
> Scott

Hi Alain,

Works perfectly now - what a massive improvement - you've made my day.

Thanks again !!!

Here's the New Renders: https://flic.kr/s/aHBqjzwszc

Regards,
Scott


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From: Kenneth
Subject: Re: Lighting Artifacts Help ?
Date: 20 Jan 2022 06:55:00
Message: <web.61e94ce7884f25c24cef624e6e066e29@news.povray.org>
Alain Martel <kua### [at] videotronca> wrote:


> >
> > Hmm - I tried to post my POV file as a zipped attachment - I selected it
> > but it doesn't appear to upload it anywhere. Did same on this message.
>
> Attachments are not allowed in this group. You can only have attachments
> in the groups that have .binaries. in their names.
> For scene files as zip files, you want to use povray.binaries.scene-files
> For shorter scene files, you can use povray.text.scene-files
> For images, you want to use povray.binaries.images
>

Actually, any attachments do show up here in the web-portal version of the
newsgroups, which is what I use. Scott's file attachment showed up as
Attachments:
Download 'pov9.zip' (562 KB)

This is relatively new behavior (maybe within the last two years?) I think the
idea was instituted as a way to keep various 'different' assets of a post 'all
in one place', rather than scattered among the various binaries' groups. This
makes it easy to post an image as a *reply* to, say, a question in the 'general'
category, if the image can help explain something there. (And the image will
still show up in the 'images digest'.)

But I guess that this change only affected the web portal version(?). That
obviously presents a problem for non-web-portal users, who will not see the
attachment. I didn't know this until now.

Of course, if I am just posting an image for comments, I'll definitely use the
binaries.images group. Or a scene text file in *its* appropriate group. Etc.


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