POV-Ray

The following scene causes a crash:

sphere {
  <0,0,0>, 1
  finish { subsurface { translucency 1.0 } }
}

global_settings {
  subsurface { }
}

Currently POV-Ray does not support rendering lens flare effects, however, they can be simulated using a macro (include file) by Chris Colefax.

I would like to suggest adding a feature to POV-Ray to support lens effects “natively” since

• as far as I know the macro has been designed for POV-Ray 3.1 so with each new POV-Ray version it gets more likely that this macro does not work properly any more
• the macro does not work when rendering with radiosity, probably because the macro creates the lens effect by using a pigment with a high ambient value (which is ignored by POV-Ray 3.7’s radiosity algorithm).

Additionally, the macro is not quite easy to employ because

• it needs to know the exact camera parameters (location etc.) and defines an own camera itself so any important camera information has to be stored if the effect has to work as expected
• it does not (actually cannot) take into account that objects may (partially) hide the lens effect
• reflections and refractions (of light sources) cannot be combined with it properly - the user would have to calculate both the point where the reflected/refracted light source can be observed and the shape it then has due to distortion, and in more complex scenes such computations are nearly impossible in SDL.

I would suggest integrating such a lens flare rendering feature with the “looks like” mechanism you already have for light sources. Several parameters that can currently be set for the macro - including effect brightness and intensity, lens options and whether to create a flare at all - could be set for the light source.

Then POV-Ray could store the location and colour of each ray that finally intersected the “looks like” object of a light source and, having finished the main rendering, from that data compute a partially transparent “lens flare layer” eventually mixed into the rendered image. By this, the above mentioned problems could be avoided:

• an object fully or partially intersecting a light source’s “looks like” object would also reduce the number of pixels used to create a flare - and therefore reduce that flare until fully hiding it
• the same goes for reflected and/or refracted versions of the “looks like” object
• the camera’s location and other properties would be used automatically
• and finally, as a feature supported by POV-Ray itself, there would be neither compatibility issues nor problems like the effect not fitting together with radiosity.

Do not get me wrong, I would not expect POV-Ray to really calculate intersections that naturally happen in a camera lens, causing lens flares. Effects looking appropriate can actually be created just in 2D space (as some graphics programs do support) so the work to be done would, as far as I have any overview, be:

• storing, as mentioned above, the relevant data for pixels showing “looks like” objects
• calculating a lens flare from that data after the render has finished
• overlaying the rendered image with the newly created lens effect.

It appears as a side effect of investigation of #294: the code in isosurf.cpp, inside
bool IsoSurface::Function_Find_Root_R(ISO_ThreadData& itd, const ISO_Pair* EP1, const ISO_Pair* EP2, DBL dt, DBL t21, DBL len, DBL& maxg)

	if(gradient < temp)
		gradient = temp;

is not thread-safe (The code is used at render time, there is a data race between < and = operation, as gradient is stored in the global object and accessed in write mode by the cited code)

It is only important if the gradient is initially undervaluated (otherwise, all is fine, no write-access)

circular area lights exhibit some anisotropy, being brighter along the diagonals than on average, as can be demonstrated with the following scene:

//+w800 +h800
#version 3.7;
global_settings{assumed_gamma 1}
plane{-z,-10 pigment{rgb 1} finish{ambient 0 brilliance 0}}
disc{0,z,10000,0.5}
camera{orthographic location z look_at 10*z up y*12 right x*12}
light_source{-10*z rgb 10 area_light 10*x 10*y 257 257 adaptive 4 circular}

In version 3.7.0.RC7.msvc10.win64, there is a bug in rendering Bézier patches in which four points (along one edge) are all the same point.

The rendering can be seen here:
http://i.imgur.com/eq2UIXR.png [Edit: See attachment for the rendering]

As you can see, there is a visible unwanted artifact in the corner of each patch. The two patches shown are essentially the same, except with the 4×4 matrix of vertices transposed (just to demonstrate that simply transposing it didn’t fix it).

Expected rendering is a smooth surface without the artifact.

Below is the code used to render the above example.

#version 3.7;

global_settings { assumed_gamma 1.0 }

camera {

  location <45, 31, -10>
  look_at <40, 21, 200>
  right x*image_width/image_height

}

light_source {

  <660, 300, -525>
  color rgb 1

}

Example 1: First point in each row is the same point
bicubic_patch {
type 1 flatness 0.001
u_steps 4 v_steps 4
<32.2168, -23.78125, 0>, <34.4968, -23.78125, 0>, <35.2168, -23.78125, -0.72>, <35.2168, -23.78125, -3>,
<32.2168, -23.78125, 0>, <34.4968, -22.10256, 0>, <35.2168, -21.57244, -0.72>, <35.2168, -21.57244, -3>,
<32.2168, -23.78125, 0>, <33.9709, -21.55577, 0>, <34.52483, -20.85299, -0.72>, <34.52483, -20.85299, -3>,
<32.2168, -23.78125, 0>, <32.30556, -21.50298, 0>, <32.33359, -20.78352, -0.72>, <32.33359, -20.78352, -3>
rotate 180*x scale 1.4
translate ←5, 0, 0>
pigment { color <1, 0, 0> }
} Example 2: First row is all the same point
bicubic_patch {

  type 1 flatness 0.001
  u_steps 4 v_steps 4
  <32.2168, -23.78125, 0>, <32.2168, -23.78125, 0>, <32.2168, -23.78125, 0>, <32.2168, -23.78125, 0>,
  <34.4968, -23.78125, 0>, <34.4968, -22.10256, 0>, <33.9709, -21.55577, 0>, <32.30556, -21.50298, 0>,
  <35.2168, -23.78125, -0.72>, <35.2168, -21.57244, -0.72>, <34.52483, -20.85299, -0.72>, <32.33359, -20.78352, -0.72>,
  <35.2168, -23.78125, -3>, <35.2168, -21.57244, -3>, <34.52483, -20.85299, -3>, <32.33359, -20.78352, -3>
  rotate 180*x

  scale 1.4
  pigment { color <1, 1, 0> }

}

[EDIT: Original title was “radiosity causing black patches when using emission less than 0”]

see attached image for reference.

mountain on left has emission set to -.13 and black patches show up, when emmission set to 0 or greater no patches

changing max_trace or any radiosity settings has no effect

setting no_radiosity on mountain fixed problem as a temp fix

code sample ...

#version 3.7;

#default { finish { ambient 0 } }
#declare rad_lvl = 4;

global_settings {
  assumed_gamma 1
  max_trace_level max(5,rad_lvl*3)
  adc_bailout .007
  ambient_light 0
  radiosity {
   pretrace_start 64/max(image_width,image_height)
   #if(rad_lvl)
    pretrace_end max(2,int(8/rad_lvl))/max(image_width,image_height)
   #else
    pretrace_end 32/max(image_width,image_height)
   #end
   count pow(rad_lvl+1,2)*10
   nearest_count 1
   #if(rad_lvl) error_bound 1/rad_lvl #end
   low_error_factor max(.4,(8-rad_lvl)/10)
   recursion_limit 1
   gray_threshold .25
   brightness 1
   max_sample 1
   normal on
   media off
   always_sample off
   minimum_reuse min(.008,8/max(image_width,image_height))
   maximum_reuse .1
   adc_bailout .02
  }
}

#declare sunC = rgb <1, 1, .9925>; // actual D65 standard illuminant
#declare SkyC = rgb <.3195, .5745, .8805>;
#macro GammaAdj(C,G) rgb <pow(C.red,G),pow(C.green,G),pow(C.blue,G)> #end

light_source {
  50000*y
  sunC*1.06
  area_light <-300, 0, -300>, <300, 100, 300>, 3, 3
  rotate <-28, 0, 14>
  adaptive 0
  circular
}

 sphere { 0, 1
  texture {
   pigment{
    gradient y
    pigment_map{
     [.07 GammaAdj(SkyC,.5)]
     [.2 average pigment_map { [.5 GammaAdj(SkyC,.75)][1 wrinkles turbulence .65 octaves 5 lambda 3 omega .9 color_map { [.2 rgb 1][.5 SkyC] } scale <10, .1, 1>] }]
     [.4 GammaAdj(SkyC,1.15)]
     [.5 GammaAdj(SkyC,1.35)]
    }
    rotate -75*y scale <1, 1, 100>
   }
   finish { diffuse .72 }
  }
  scale 100000
  inverse
 }


#declare Cam_pos = Cam_pos + <0, 20, -40>;
#declare Cam_lkt = Cam_lkt + <0, 10, 50>;
camera {
  location Cam_pos
  direction <0,0,1>
  right 1.33*x
  up y
  sky <0,1,0>
  #if(Cam_agl) angle Cam_agl #end
  look_at Cam_lkt
}

#macro sinai(HillQ)
 #local F = function { pattern { granite poly_wave 4 turbulence .01 lambda 2.1 omega .9 scale 5 translate <.2, 0, 18.08> scale <2, 1, 3> } }
 #local N = function { pigment { crackle ramp_wave turbulence .3 lambda 2.2 omega .76 color_map {[0 rgb 0][1 rgb 1] } scale .07 translate <-.15, -.12, .13> } }
 height_field {
  function HillQ, HillQ { F(x,y,z) + N(x,y,z).grey/47 }
  water_level .05
  clipped_by { box { <0, .05, .3>, <1, 1, 1> } }
  translate <-.5, -.05, -.5>
  rotate 20*y
  texture {
   pigment{ crackle color_map { [0 rgb <161, 107, 71>/255][.25 rgb <193, 132, 93>/255][.35 rgb <218, 163, 123>/255][.45 rgb <212, 153, 112>/255][.55 rgb <222, 166, 125>/255][.65 rgb <236, 178, 124>/255][.75 rgb <220, 154, 102>/255][.85 rgb <160, 121, 103>/255] } turbulence .75 lambda 3 omega .7 scale .1 }
   finish{ diffuse albedo .56 emission -.13 specular .25 roughness .02 brilliance 1.5 metallic 1.3 }
   normal { crackle poly_wave .7 turbulence .4 omega .8 scale <.007, .03, .007> }
  }
  rotate 12*y
  scale <2400, 2000, 3000>*1.5
  translate <1900, 0, 1900>
  scale <-1,1,1>
  no_radiosity
 }
#end


sinai(1600)
plane { y,0 pigment { rgb <1, 1, 1> } }

//courtyard gating not included due to size of code and many external files needed. add anything around <0,0,0> to try to reproduce effect of error

not sure if this is something needing further work or an intended effect.

Shadows from and area light with area_illumination on seem to follow the same shadow calculation as a standard area light by giving more weight to lights near the center of the array. I would assume the shadows would be calculated similarly to individual lights in the same pattern as the array by evenly distributing the amount of shadow equally for each light. But this is not what I see.

The code sample below when rendered with scene 1 will show shadows grouped near the center from the area light with area_illumination. If scene 1 is commented out and scene 2 is uncommented then rendered, you will see evenly distributed shadows from individual lights. Area lighting with area_illumination I would assume should give a result identical to scene 2. If scene 1 is rendered with area_illumination off, the shadow calculation is exactly the same as with area_illumination on.

example images rendered on win32 XP

#version 3.7;

global_settings {
 ambient_light 0
 assumed_gamma 1
}

camera {
  location <0, 3, -5>
  look_at <0, 2, 0>
}

background { rgb <.3, .5, .8> }
plane { y,0 pigment { rgb .7 } }
torus { 1.5,.1 rotate 90*x translate 4*z pigment { rgb .2 } }
plane { -z,-7 pigment { rgb .7 } }

/*
// scene 1
light_source{
  y
  1
  area_light 3*x, z, 7, 1
  area_illumination on
}
union {
 sphere { 0,.05 }
 sphere { .5*x,.05 }
 sphere { x,.05 }
 sphere { 1.5*x,.05 }
 sphere { -.5*x,.05 }
 sphere { -x,.05 }
 sphere { -1.5*x,.05 }
 translate y
  hollow pigment { rgbt 1 } interior { media { emission 10 } }
}
// end scene 1
*/


// scene 2
#declare Light = light_source {
  0
  1/7
  looks_like { sphere { 0,.05 hollow pigment { rgbt 1 } interior { media { emission 10 } } } }
}

union {
 object { Light }
 object { Light translate .5*x }
 object { Light translate x }
 object { Light translate 1.5*x }
 object { Light translate -.5*x }
 object { Light translate -x }
 object { Light translate -1.5*x }
 translate y
}
// end scene 2

If a blob is intersected by something else, the composite object has incorrect refractions if it is too small (in absolute units). Having the same object constructed without a blob, the errors happen at much smaller scales. The errors don’t affect solid objects, just refractions.

An example shows a half-sphere, constructed as CSG sphere + plane, and identical half-pshere, constructed as CSG blob + plane. When the scale of the entire construction is changed, the refractions disappear first for the blob, and at 100x times smaller scale, also for the sphere. The right side shows the solid version, showing that the surface intersection test is ok, it’s just the refraction that fails.

The problem is not present when looking from the curved side (the blob side). So the ray that hits the blob, gets refracted correctly, but the ray that hits the intersecting plane first, and should then refract in the blob from the inside, doesn’t work. If in attached sphere, you exchange -y with y in clipping planes, everything is ok.

The scale when this happens is not very small - blobs of radius 0.02 already fail (noticed because in 1=1metre scale, blob raindrops on a glass plate didn’t have intersections when looking from the back).

Examples are named by factor=9,0.9,0.09,0.009 and you can see first the blob (top) refraction gets smaller and disappears, then later the bottom (sphere) also gets the same problem.

with reference to http://bugs.povray.org/task/46

still some issue with area illumination and light fading when interacting with media

seems light fade is not taken into account with scattering media.
emission and absorption media seem to work fine.
occurs with all scattering types.

#version 3.7;

global_settings {
 ambient_light 0
 assumed_gamma 1
}

camera {
  location <0, 3, -5>
  look_at <0, 2, 0>
}


#declare Light = 3; // light 1 = individual lights
                   // light 2 = standard area light
                   // light 3 = area light with area illumination

#declare Fade = 1; // light fading: 1 on, 0 off

#declare Media = 1; // media 1 = scattering
                    // media 2 = emission
                    // media 3 = absorption

#declare Type = 1; // scattering media type


#switch(Light)
 #case(1)

  #declare Ls = light_source {
    0
    1/7
    #if(Fade) fade_distance 2 fade_power 2 #end
  }

  union {
   object { Ls }
   object { Ls translate .5*x }
   object { Ls translate x }
   object { Ls translate 1.5*x }
   object { Ls translate -.5*x }
   object { Ls translate -x }
   object { Ls translate -1.5*x }
   translate y
  }

 #break
 #case(2)

  light_source{
    y
    1
    area_light 3*x, z, 7, 1
    #if(Fade) fade_distance 2 fade_power 2 #end
  }

 #break
 #case(3)

  light_source{
    y
    1
    area_light 3*x, z, 7, 1
    #if(Fade) fade_distance 2 fade_power 2 #end
    area_illumination on
  }

 #break

#end


cylinder { <0, .01, 0>, <0, 5, 0>, 2 pigment { rgbt 1 } hollow no_shadow
 interior {
  media {
   #if(Media = 1) scattering {Type, 30 } #end
   #if(Media = 2) emission 2 #end
   #if(Media = 3) absorption 2 #end
    density { cylindrical turbulence 1.5 scale <1, .14, 1> }
  }
 }
 scale <.15, 1, .4> translate 4*z
}

plane { y,0 pigment { rgb .7 } }
plane { -z,-7 pigment { gradient y color_map { [.5 rgb 1][.5 rgb 0] } } }
union {
 sphere { 0,.05 }
 sphere { .5*x,.05 }
 sphere { x,.05 }
 sphere { 1.5*x,.05 }
 sphere { -.5*x,.05 }
 sphere { -x,.05 }
 sphere { -1.5*x,.05 }
 translate y
  hollow pigment { rgbt 1 } interior { media { emission 10 } }
}

A low priority thought for the future: isosurface now only allows contained_by to be a sphere or a box. It would be more intuitive to allow the same objects that are allowed in clipped_by and bounded_by (although it probably needs to be finite). It would enable allow much faster rendering in many cases:

1) There are a lot of cases when the sphere or a box are very bad in bounding - if an object has a hole, a torus may be better, and in many cases, cylindrical bounding would help a lot.
2) Sometimes, having a too large contained_by object includes far-away parts of the iso-function, and expose large gradients that you want to avoid. If a bounding object is better, you can decrease the max_gradient and speed up the render.
3) The isosurface is usually much more expensive to calculate than any normal bounding object, so it’s an improvement even if the intesection test is not as fast as bounding box.
4) A typical case: if you use texture-like functions to make the surface realistically rough, you know almost exactly what the bounding object is - it can be the original unmodified object.
5) For isosurface terrains, a preprocessing macro could create a rough mesh-like bounding object to contain the “mountains”, thus making everything faster.
6) In case you want clipping, having the contained_by set to the same object probably avoits calculating too many intersections.

The main modification is probably that the intersections of bounding objects can be split into more than one interval - but it’s probably worth it, the isosurfaces are usually a speed bottleneck.

When rendering for some time, it occasionally happens that POV-Ray appears twice in the Windows taskbar. One button is the normal one, the other one does not open any window when clicked on and reads something like “99% complete” (see attached image), like the render window’s title, but obviously unrelated to it (probably the title the render window had shortly before?). After stopping the render, the odd taskbar button remains there until POV-Ray is closed.

• Observed under Windows XP
• POV-Ray 3.7.0.RC7.msvc10-sse2.win32
• When applications are summarized into groups in the taskbar by Windows, the odd POV-Ray button is attached to the Windows Explorer group
• Run with render priority set to “high”

Is this a Bug in Windows or in POV-Ray?

Here are two low-priority bugs in POV-Ray’s GUI, observed by me under Windows XP, which should be easy to fix I think:

• In the “Insert” menu, there are sub-menus (e.g. “Radiosity and Photons”) in which there are menu seperators at the end of the popped-up menu bar.
• The progress bar in the top-right corner of the editor window seems to be too large for the window (203px) and therefore clipped. As a result, progress seems to be 100% when it is not yet, e.g. at 90% progress. (Have not measured exactly.)

Both bugs are not severe at all, but it would be nice if they could be fixed.
By the way, a second progress bar could be added to visualize the number of frames already rendered in an animation.

Up to POV-Ray 3.7 RC7 it has not been possible so far to declare custom properties for POV-Ray’s objects, which would be especially useful for complex objects defined in include files.

Currently, if you want to have an object (e.g. a car) with certain variable parameters (e.g. colour, wheel rotation, ...) defined in an include file and the parameters set by a scene file which uses the include file, you have to choose one of the following approaches:

1. use a macro

#macro car(colour, wheelrot, ...)
  ...
#end

or, 2. check parameters declared before, e.g.

#declare car =
union {
  
  #ifdef (colour)
    #local colour_internal = colour;
  #else
    #local colour_internal = default_colour;
  #end
  
}

The resulting object would be used in the following way:

  #include "car.inc" // include file once
  object {
    car(rgb <1,0,0>, 0, ...) // macro approach
  }

  // other approach
  #declare colour = rgb <1,0,0>;
  #declare wheelrot = 0;
  ...
  #include "car.inc" // include file every time you want to have a car object instance
  object {
    car
  }

Needless to say, both approaches are not quite optimal.

• The macro approach needs only one #include directive and name conflicts will (hopefully) not be a problem. However, one would have to look up the parameter order of the macro in the include file, in the worst case every time the macro is used.
• The other approach needs as many #include directives as car objects shall be instantiated, there can arise name conflicts with other inculde files used in the scene, and a (potentially long) list of parameters has to be declared before each #include. On the other hand, with this approach for any value it is clear which information it gives, e.g. #declare colour = rgb <1,0,0> can easily be read as ‘set car colour to “red”‘.

My suggestion would be creating an SDL feature to

• declare which properties a certain object can have
• set these properties inside the object statement in which the object is used.

One step up could be to even declare object classes along with them.

This could look like this:

// include file code
class car { // alternatively (without classes) use #declare car = object { ...
  property colour = rgb <1,0,0>; // with default colour
  
  union {
    ...
  }
}

// scene file code
car { // alternatively (without classes) use object { car ... }
  colour rgb <0,0,1>
}

Note that this solution makes the declarations much more concise and easy-to-read. Especially in scenes with many includes and animation scenes where objects’ properties have to be manipulated according to sometimes complex functions, this would be very useful. Please also consider that such user-defined objects can have dozens of properties.

When resolution is not specified (neither via POVRAY.INI nor via QUICKRES.INI nor via command line or custom .ini file), random values are displayed for image resolution in the Image Output Options message output. (The actual render will be performed at the default size of 160×120 pixels though.)

When a command-line parameter in an .ini file cannot be parsed (such as “+a.3”), POV-Ray reports a “Problem with setting”, quoting the command line, rather than indicating that the problem occurred in an .ini file. This leads the user to think that the problem is with the command line itself, unnecessarily confusing him.

Draw_Vistas, Light_Buffer, and Vista_Buffer (plus associated switches) do not issue warning when used, even tho code has been disabled.

Now the editor remembers only the cursor positions of the loaded files when starting a new PR session. It would be more friendly to remember whether the window was split or not, as well as the bookmarks.

As emerged as an idea during the discussion of FS#299, an SDL / POV-Ray editor feature would be useful that allows API documentation via formal comments, e.g. in include files:

/**
 * Creates a car object.
 * @param a
 *        description of param a
 * ...
 */
#macro car(a,b,c)
  ...
#end

In addition to the ability of (auto-)generating a documentation file from such comments, an editor window feature would be convenient that allows popup display of a macro’s (object’s / parameter’s / ...) documentation section.

When using OpenEXR output file format, POV-Ray erroneously reports it as “24 bpp EXR” in the message output, while in fact it generates a 3×16 = 48 bpp file.

Code inspection shows that we’re still using fseek() and ftell() in various places (including text file input), which can’t handle file positions of 2GB and beyond (except on 64-bit linux machines); those calls need to be examined and (where appropriate) replaced with the fseek64() macro we’re already defining (but currently not using), and a to-be-defined ftell64() macro.

One potential (untested) error scenario would be a scene file calling a macro that is defined at the end of a > 2GB long include file.

If enabled, POVray always created backups of pov and inc files once per session.
Now using 3.7 RC6 only pov file backups are created but not from inc files.

From Thomas de Groot

Using the following code for a (sky) sphere in a scene, with light source well outside the sphere;
works correctly until the above scale value. Use a value of >=100*10e4 and the sphere becomes black.

#version 3.7;
global_settings{ assumed_gamma 1.0 }

#declare T_sky =
texture {
  pigment {
    gradient y
    pigment_map {
      [0.0 srgb <1.0,0.7,0.6>*1 transmit 0.5]
      [1.0 srgb <0.8,0.1,0.0>*1 transmit 0.5]
    }
  }
  finish {
    emission 0.9
    diffuse 0.0
  }
}

#declare T_cosmos =
texture {
  pigment {
    color rgbt <0,0,0,1>
  }
  finish {
    ambient 0.0
    diffuse 0.0
  }
}

sphere {
  <0,0,0>,1
  texture {T_sky}
  interior_texture {T_cosmos}
  no_shadow
  no_reflection
  inverse
  scale 99.9*10e4
}

Working with windows version of POV-Ray and Win7 x64

Is this normal for version 3.7 RC5? I seem to remember that with lower
versions of POV-Ray on could go at least to 10e6. Especially with the
Ringworld scenes back in 2010 the scales used where much larger without
any black out.

I can indeed confirm that the Ringworld scene does not render correctly anymore, with identical black out.

photons are not working when used with a light_group. verified in NG posting in p.general a simple scene file is attached.

At times, the current method of specifying texture for
CSG components and compounds is restricting. The issue
pops up now and then, see e.g.

http://news.povray.org/povray.pov4.discussion.general/thread/%3Cweb.4799def8e1857b77c150d4c10%40news.povray.org%3E/

http://news.povray.org/povray.general/thread/%3Cweb.4fc892634f065c00e32b83540@news.povray.org%3E/

http://news.povray.org/povray.general/thread/%3Cweb.5073e9f7dae1fbb2d97ee2b90%40news.povray.org%3E/

There should be a new CSG option “texture_mode” or similar, which could take
one of the following values:

preserve (the current behavior)
cutaway (the current behavior when specifying cutaway_textures)
override (replace all individual textures with compound texture)
layer (layer the compound texture over the existing textures)

and possibly, more involved

modify/merge: if both element and compund textures are simple, i.e.
not layered or mapped, override all default values of the element
textures with the values from the compound texture. The idea would
be to, e.g., have the elements already pigmented but then apply
common normal or finish properties.