October to middle November, I prodduced a 5 minutes video mainly py POVRAY.

Here a part of the video.ini file

#

Whenever some object is to be periodically repeated in some kind of grid, you can achieve this with macros, but it
a) wastes a lot of resources

 even if object references are implemented in the future, wrapper with its own transformation matrix still takes space and bookkeeping

b) is not infinite

 annoying when making infinite planar tiling with arbitrary objects
 like an approximate water surface or tiling with real bricks
 or anything that needs to extend to horizon

c) is not optimized for periodicity

I think it can be very efficiently implemented as an object that takes a finite object argument (like CSG functions) and can be periodic in either 1D,2D or (possibly dangeorous?) 3D with specified period. In each dimension, the number of repetitions can be any integer or even infinity (or max_int). Something like
periodicity <2,2,Infinity> 2 copies in 1 direction, 2 in the other, infinite in the third
grid_separation <1,2,2> 1 unit size in first direction, 2 unit sizes in the other two

All the code needs to do is raytrace in the current unit cell and if the ray passes uninterrupted, pass it through the neighbouring unit cell (which means trace a translated ray through the same object). The object itself would just feel an additional clipping box, everything else would work seamlessly.

In case of infinite column of transparent object, max_trace stops the infinite loop anyway.

This is just a suggestion, I realize this is more of a long-term change but it is quite easy to implement and would simplify a large number of projects.

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.

The SDL currently provides no way to compute the exact direction of a spline at a given location, even though mathematically this is a piece of cake: The first-order derivative of any spline section gives you the “speed” as a vector function, and is trivial to compute for polynomial splines (which are behind all spline types that POV-Ray supports); the normalized “speed” vector, in turn, gives the “pure” direction.

For exact direction/speed computations, I propose to extend the SDL invocation syntax as follows to allow for evaluating a spline’s derivative:

    SPLINE_INVOCATION:
        SPLINE_IDENTIFIER ( FLOAT [, SPLINE_TYPE] [, FLOAT] )

or

    SPLINE_INVOCATION:
        SPLINE_IDENTIFIER ( FLOAT [, FLOAT] [, SPLINE_TYPE] )

where the second FLOAT will specify the order of derivative to evaluate (defaulting to 0). In order to compute the position, direction, and acceleration of an object traveling along a certain spline, one could then for instance use:

    #declare S        = spline { ... }
    #declare Pos      = S(Time);
    #declare VSpeed   = S(Time,1);
    #declare VAccel   = S(Time,2);
    #declare Dir      = vnormalize(VSpeed);
    #declare Speed    = vlength(VSpeed);
    #declare AccelDir = vnormalize(VAccel);
    #declare GForce   = vlength(VAccel) / 9.81;

Alternatively, a mechanism may be devised to create a spline representing another spline’s derivative; however, it would be debatable whether the syntax should be parameter-like (being an added information that could be overridden again when creating other splines from such a derived spline), or operation-like (converting the spline), and in the latter case how it should affect spline type (and consequently control points); so the spline invocation parameter approach might be more straightforward, with less potential surprises for the user.

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.

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.

the pigment {} and normals {} sections allow spatial variation of color, transparency and normal map. On the other hand, the specular parameter is a fixed scalar. This removes many possibilities. For instance, specularity could vary in space (speckles of oil or water on a surface, worn-out finish, having specularity reduce where the pigment transparency increases) and have color components. With current settings, the light’s color is simply multiplied by the scalar specified by “specular”, whereas multiplying each component with different color could create diverse effects (the “metallic” keyword already acts similar to duplicating the specular color from the pigment). The syntax could be exactly the same as for the pigment (all the patterns, color maps, image maps and functions would apply, allowing reuse of most of the code).

The effect can now be partially faked by having patterned textures, but it requires a very complex code and the lack of layering of patterned textures makes it difficult to vary the specularity and pigment separately.

In a similar way, roughness and brilliance could also vary in space.

Doing the same for varying reflectivity would be more difficult, as it has angular dependence and possibilty of Fresnel calculation, but it could at least be a full color instead of a simple scalar multiplier. For instance, having a blue surface that reflects only red component of the light should not be impossible.

I think at least part of this functionality actually makes the scene description language more uniform and self-consistent.

When placing a transparent object inside another object which contains media, artefacts may occur (see attached file). They look similar to specular highlights or are just strange white spots in the image.

I discovered artefacts of that kind first in the image of which MediaArtefactDetail.png is a cropped part. The code I managed to reproduce such artefacts with contained a “starfield” sphere

sphere {
  <0,0,0>, 1
  
  pigment { rgbt 1 }
  
  interior {
    media {
      emission rgb 1/10
      density {
        crackle form <1,0,0>
        density_map {
          [0.0 rgb 1]
          [0.05 rgb 0]
        }
        scale 0.002
      }
    }
  }
  
  scale 1000
  
  hollow on
}

and a transparent sphere

sphere {
  <0,0,0>, 1
  
  pigment { rgbt 1 }
  
  scale 2
  
  hollow on
}

which is, obviously, completely inside the other sphere. So is the camera.

Since the sphere has a pigment { rgbt 1 }, it should be completely invisible, which is correctly rendered as long as the scaling factor is 1 and hollow off (MediaArtefact1.png). Changing hollow to on does not yet produce the artefact, but the right half of the output image seems to be shifted by one pixel (MediaArtefact2.png). Changing the scaling factor to 2 (as it is in the above code) produces the artefact (MediaArtefact3.png). Changing the camera location (MediaArtefact4.png) does not change anything, the artefact just “moves with the sphere”. Changing the sphere size again, however, seems to stir up the “stars” in the “starfield” sphere while not removing the artefacts (MediaArtefact5.png). Changing hollow to off again does neither (MediaArtefact6.png).

The artefacts are definitely no specular highlights. There is not even a light source in the scene that could produce any. I used POV-Ray 3.7 RC6 to render the images, but the artefact shown in MediaArtefactDetail.png already occured in POV-Ray 3.6 which I used to render that image.

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.

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.

[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

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 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.

The following scene causes a crash:

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

global_settings {
  subsurface { }
}

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.

On a very long render, around day 24, the elapsed time display becomes incorrect, showing 4294967272d 4294967272h 4294967272m 4294967272s.

Found on Windows 7 64 bits and reproduced on Windows 7 32 bits.
NOT reported on other platforms.

When working with predefined materials, it would be useful to have something like:

#if (!Use_photons)
  #default { interior { caustics 1 } }
#end

#include "my_predefined_materials.inc"

Default medias or IORs could also be useful.

Tooltip popup for render speed always displays as “Pixels per Second” rather than matching status bar. I’ve noticed it in 3 renders so far. Most of my renders are fast enough not to see any other unit besides PPS, but I should be able to reproduce again if necessary.

Povray 3.7 has rendering artifact in meshes with polygons that meet at shallow angles. Please see the attached file.

The part of concern is the mesh2, which produces the partly-transparent faces of a shallow pyramid. The file result-3_6.png shows the output of povray-3.6, and the file result-3_7.png shows the output of povray-3.7. In 3.7, you can see a thin light-colored margin all around the base of the pyramid, especially thick under the top cylinder. In 3.6, this artifact is absent. For comparison purposes, I have inserted a “#version 3.6;” directive at the top of the file so that the output images are as close to each other as possible. However, the artifact is still present in 3.7 without this directive.

The attached scene file is only a small part of a much larger scene, where this artifact shows up in numerous very obvious places, where it doesn’t in 3.6. I have hunted in the documentation and online for ways to solve this problem, but haven’t found anything. Because of this, I am forced to stay with 3.6 for production use, which is quite unfortunate since I’d like to take advantage of the new features of 3.7.

Due to a typo in the conf file parser (introduced, I think, in refactoring after 3.6), the restricted setting is ignored, and access checks aren’t performed.

Fixing this reveals some other issues:

• %INSTALLDIR%/../../etc is incompletely canonicalized to /usr/local/share/../etc, not /usr/local/etc
• read+write paths are added to the read list only, so writing is impossible

See attached patch.

Relatedly, I think it would be nice to add a new replacement token %CONFDIR% instead of %INSTALLDIR%/../../etc.

Also, there’s a realpath function that could simplify path handling, though I’m not sure if it’s available on all platforms.

pov 3.7 Can not identify the Chinese.I give the texture map filename in chinese,it turns out parse error.

The following command fails with parsing error:
povray +OqXfFbD0Vg5XjZgi5sOefkvdF_oCGrZ1ChVhrQw==.png +IqXfFbD0Vg5XjZgi5sOefkvdF_oCGrZ1ChVhrQw==.pov +W1000 +H1000

The following command succeeds:
povray +OqXfFbD0Vg5XjZgi5sOefkvdF_oCGrZ1ChVhrQw.png +IqXfFbD0Vg5XjZgi5sOefkvdF_oCGrZ1ChVhrQw.pov +W1000 +H1000

Any option that gets a filename as parameter will fail if it contains ‘=’.

It is a regression, as it worked fine with 3.6.

When you press alt+b or access the “about” dialog in the Help menu it displays some text including software version number and list of contributors.

It would be nice to be able to select and copy this text using this mouse. Sometimes in the newsgroup I have to tell people what version of POVray I am using, and typing the version number can be a pain.

It would be nice to be able to specify colors in HLS as well as RGB.

Currently, you can use a macor to convert individual colors. But this does not work in color_maps where you want smooth gradations/interpolations between two or several colors.

This doesn’t work:

#declare pavement_object = array[2]
{

object {trash_can_macro()	scale 3/4			translate -x * 1/2},
object {potted_plant_macro(_CT_rand2)	scale 3/4	scale 3/2	translate -x * 1/2}

}

This does work:

#declare trash_can_object = object {trash_can_macro()};
#declare potted_plant_object = object {potted_plant_macro(_CT_rand2)};
#declare pavement_object = array[2]
{

object {trash_can_object	scale 3/4			translate -x * 1/2},
object {potted_plant_object	scale 3/4	scale 3/2	translate -x * 1/2}

}

Logically, I cannot see a reason for this to be so.

Subsurface scattering must be made photon-aware.

Near concave edges, radiosity samples may be re-used at a longer distance away from the edge than towards the edge; there is code in place to ensure this, but it only works properly where two surfaces meet roughly rectangularly, while failing near the junction of three surfaces or non-rectangular edges, potentially causing “cross-talk”.

It should be investigated how the algorithm can be improved or replaced to better cope with non-trivial geometry.

Some features are optional in custom builds of POV-Ray (I’m thinking about OpenEXR in particular); it would be nice to have a syntax for an SDL script to check for support of such features, so it may take some fallback action if the feature is not supported.

Background

Possible solution

The current 32-bit linear congruential generator used as RNG in POV-Ray is sometimes quite limited for some purposes and in a few cases its poor quality shows up (as has been demonstrated more than once in the newsgroup). Thus it would be nice if POV-Ray offered additional, higher-quality random number generators, besides the current one (which should probably remain for backwards compatibility). These RNGs could include algorithms like the Mersenne Twister and the ISAAC RNG, both of which have very decent quality and have an enormous periods (while at the same time being very fast).

After a long discussion, the following syntax for specifying the RNG type and seed (which may be larger than 32 bits) has been suggested:

seed(<value>) | seed(<type>, <value> [, <values>])

For example:

#declare Seed1 = seed(123); // Use the current RNG, with seed 123
#declare Seed2 = seed(1, 123); // Identical to the previous one
#declare Seed3 = seed(2, 456, 789, 123); // Use RNG algorithm #2,
                                         // with a large seed (96 bits specified here)

A C++ implementation of the ISAAC RNG can be found at http://warp.povusers.org/IsaacRand.zip

When you instantiate an object several times, eg:

object { MyObj translate -x*10 }
object { MyObj translate x*10 }

POV-Ray will copy that object in memory, at least for most types of objects. Not for all of them, though. Most famously if MyObj is a mesh, it won’t be copied, but only a reference to the original will be used, thus saving memory. (There are a few other primitives which also don’t cause a copy, such as bicubic_patch and blob, but those are naturally not so popular as mesh, so it’s a less known fact.)

AFAIK the reason why referencing (rather than copying) is not used for all types of objects is rather complicated, and mostly related to how transformations are applied to these objects. For example if the object being instantiated is a union, the translates above will be (AFAIK) applied to the individual members of the union rather than to the union object itself.

Copying, however, can be quite detrimental in some situations. For example if you have a huge union, and you want to instantiate it many times, the memory usage will be that many times larger (compared to just one instance). This is sometimes something which the user would not want, even if it made the rendering slightly slower as a consequence. (In other words, better to be able to render the scene in the first place, rather than running out of memory.)

Redesigning POV-Ray so that all objects would be referenced rather than copied would probably be a huge job, and in some cases a questionable one. There probably are situations where the current method really produces faster rendering times, so redesigning POV-Ray so that it would always reference instead of copy, could make some scenes render slower.

So this got me thinking about an alternative approach: How hard would it be to create a special object which sole purpose is to act as a reference to another object, without copying it? This special reference object would act as any regular object, would have its own transformation matrix and all that data related to objects, but its sole purpose is to simply be a “wrapper” which references an existing object. It could be, for example, like this:

object_ref { MyObj translate -x*10 }
object_ref { MyObj translate x*10 }

The end result would be exactly identical as earlier, but the difference is that now MyObj behaves in the same way as a mesh (in the sense that it’s not instantiated twice, but only once, even though it appears twice in the scene), regardless of what MyObj is.

In some cases this might render slightly slower than the first version (because POV-Ray has to apply the transformations of the object_ref first, after which it applies whatever transformations are inside MyObj), but that’s not the point here. The point is to save memory if MyObj is large.

An object_ref would behave like any other object, so you could do things like:

#declare MyObjRef = object_ref { MyObj };

object { MyObjRef translate -x*10 }
object { MyObjRef translate x*10 }

(The only thing being instantiated (and copied) here is the “MyObjRef” object, not the object it’s referring to, so that actual object is still stored in memory only once.)

In some situations it might even be so that referenced objects actually render faster than if the objects were copied because references increase data locality, lessening cache misses.

I believe this could be a rather useful feature and should be seriously considered, unless there are some major obstacles in implementing it.

There is an big issue with the slope pattern: when the object it is applied to is instanced (again) with a transformation (in particular a rotation, as a translation would not impact.. but a shear might), the colours of the surfaces are changed.

  
object { p translate -5*x }
object { p rotate 220*y+20*x    translate 3*x }       

Nobody would expect the object to be different in appearance.
If slope {} is replaced with wood, all is fine. (as for others textures, i guess)

IMHO, the slope vector need to be adjusted for the later transformation(s) (so as to compensate the issue of using the Perturbed Normal vector).

This should not impact the AOI/FACING (experimental) patterns, as AOI definition is pretty clear about duplicating & transform if you think about it a bit, as well as FACING: for these two, it is expected to either use the ray(current point of view) or a fixed 3D point as reference. At the limit, discussion about moving the 3D point of FACING might also be opened to interpretation.

AOI/FACING are in task #19

Front- & Back-end code should be refactored for full Unicode support in scene files and strings.

Currently, array items may only be referenced by their index number (an integer). It would be nice to also be able to assign string values as array indexes, as in other scripting languages.

Someone built a version of Povray with internal support for automatic subdivision of meshes. See:

http://www.cise.ufl.edu/~xwu/Pov-Sub/

Would like to see this feature added natively to Povray.

When rendering in multiple passes (radiosity in my case), the elapsed pixels and percentage, written to terminal
are first displayed like this:
Rendered 126202 of 360000 pixels (35%)
Then on the second stage the output text becomes shorter and you see
Rendered 25344 of 360000 pixels (7%)%)
The contents of the previous status are not erased, so the longer text persists (note the duplicate percentage sign and closing parenthesis). Such a glitch could have more drastic effect in rare cases.

I’m running
Version 3.7.0.RC3 (g++ 4.6.2 x86_64-unknown-linux-gnu)
compiled for the Arch Linux package.

The so-called shadow line artifact (http://wiki.povray.org/content/Knowledgebase:The_Shadow_Line_Artifact) which affects objects with a ‘normal’ statement as well as smooth meshes and heightfields can be really annoying sometimes. Currently the only way to remove it is to make the object shadowless, which isn’t a good solution except in very special cases.

This algorithm could remove the artifact: If the actual normal vector of the object points away from the light source (its dot-product with the light vector is negative) but the perturbed normal points towards it (dot-product positive), then ignore the first shadow-test intersection with the object itself.

There are alternative ways of implementing an equivalent functionality:

- Don’t check the condition (if it’s too difficult to check due to how the code is designed) but always ignore the first intersection with the objects itself. This will work properly with closed surfaces but not with open ones, so it might need to be a feature for the user to turn on with a keyword (similar to eg. ‘double_illuminate’).

- Alternatively, don’t ignore the first intersection, but instead ignore the “opposite side” of the object’s surface (again, possibly only if a keyword has been specified). In other words, if we are rendering the outer side of the object, ignore its inner side when shadow-testing, and vice-versa.

- Perhaps simply add a feature to make surfaces one-sided (similarly to how they can be made so in OpenGL and similar scanline rendering systems). In other words, the inner side of a surface is completely ignored everywhere, making the object virtually invisible from the inside. The advantage of this feature would be that it can have uses other than simply removing the shadow line artifact.

The sphere_sweep renders well when specified directly, but when it is scaled, its bounding box is calculated incorrectly, which clips the object so it almost disappears.

The effect is present for all three types of splines.

I’m attaching a test scene and the rendering result. The saving of the object with #declare has no effect, I just wanted to show both transformed and untransformed version.

I don’t think this issue is related to other artifacts occuring with sphere_sweep, as it is obviously an issue of the internal bounding box.

With very fast renders and very large output files, the message queue can fill up because the producers are not limited by IO, while the consumer performance is limited by disk IO. Consequently, the message queue can fill up to exhaust all available memory. The solution is to build in some better control of pending output data in the message queue on the producer side. This will also pave the way for message communication over slow links (i.e. a network).

In the photons map, the direction of each photon is stored as separate latitude & longitude angles (encoded in one byte each), causing the longitudinal direction component’s precision to be unnecessarily high for directions close to the “poles” (Y axis); in addition, encoded value -128 is never used. For better overall precision as well as precision homogenity, the following scheme could be used instead:

• Encode the latitude (-pi/2 to +pi/2) into LatCount=226 distinct values (= 256*sqrt(pi)/2) rounded to the next even number) from 0 to LatCount-1 using

latCode = (int)((LatCount-1) * (lat/M_PI + 0.5) + 0.5)

• For each latitude code, define a specific number of encodable longitude values, LngCount[latCode] = approx. cos(lat)*pi*65536/(2*LatCount); this can be a pre-computed table, and may need slight tweaking for optimum use of the code space. Encode the longitude (-pi to +pi) into a value from 0 to (LngCount[lat]-1) using

LC = LngCount[latCode];
lngCode = (int)(LC * (lng/(2*M_PI) + 0.5) + 0.5) % LC;

• Besides LngCount[latCode], also store the sum of LngCount[i] with i < latCode as LatBase[latCode]; encode the direction as

dirCode = LatBase[latCode] + lngCode;

• For decoding, a simple lookup from a precomputed list of directions could be used (2^15 entries, i.e. one hemisphere, will suffice). To conserve space, direction vectors could be scaled by (2^N-1) and stored as (N+1)-bit signed integer triples rather than floating point values; due to the limited precision of the lat/long information, 8 bits per coordinate might be enough, giving a table size of 96k. A full double-precision table would require 786k instead.

While familiarizing myself with the code, I found some small changes in the solve_cubic function that lead to a significant speedup.

In my experience, “pow” is by far the slowest function in math.h and replacing it with simpler functions usually makes a tremendous impact on the speed (it’s an order of magnitude slower than sqrt/exp/cbrt/log).

solve_cubic has a “pow” function that can be replaced by cbrt (cubic root), which is standard in ISO-C99 and should be available on all systems. Separate benchmarks of solve_cubic function show this change almost doubles the speed and does not lower the accuracy. As solve_cubic is part of the solution of quartic equation, this improves the speed for many primitives. Testing with a scene containing many torus intersection tests (attached below) I still observed almost 10% speedup (Intel, 4 threads, 2 hyperthreaded cores, antialiasing on, 600×600: from 91 to 84 seconds). And this is for a torus, where a lot of time is spent in the solve_quartic and cubic solver is only called once! Similar speedup should be expected for prism, ovus, sor and blob.

I do believe the cubic solver can be done without trigonometry, but that would mean changing the algorithm, introducing new bugs and requiring a lot of testing. However, the trigonometric evaluation can still be simplified (3% speedup in full torus benchmark).

These changes don’t affect the algorithm at all, they are mathematically identical to the existing code, so the changes can be applied immediately. I also included other changes just as suggestions. Every change is commented and marked with [SC 2.2013].

This sadly does not speedup the sturm solver, which uses bisection and regula-falsi and looks very optimized already.

The test scene I used has a lot of torus intersections from various directions (shadow rays, main rays, transmitted rays).

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> }

}

When rendering only a region of a file, using the command-line options +sc/+sr/+ec/+er, the area of the image that is excluded comes out as black in the final PNG.

Expected behaviour is for it to be transparent.