The Persistence of Vision Raytracer (POV-Ray).

This is the legacy Bug Tracking System for the POV-Ray project. Bugs listed here are being migrated to our github issue tracker. Please refer to that for new reports or updates to existing ones on this system.

IDCategoryTask TypeReported InPriority  descSeveritySummaryStatusProgressDue In Version
140Platform-specificFeature Request3.70 beta 37aVery LowLow"Reload" option in File menuTracked on GitHub
Task Description

Would be great to have a “Reload” option in the File menu to manually reload the current file from disk, discarding all subsequent changes since the last save.

47PreviewPossible Bug3.70 beta 32Very LowLowRender Preveiw window can become disabledTracked on GitHub
Task Description

If a render is continued with the +c option and the render had completed, the render preview window will disappear and the show/hide render window button will be grayed. Even after the scene is modified and the command line options have been changed, the show/hide button will still be grayed.

Opening or changing to another scene and rendering will not restore the button, nor will rendering with +d. However, if a trace is started using -d, halted, then continued using +d (or allowed to finish completely with -d and a new one is started using +d), then the preview window is restored.

This behavior is different from 3.6.1, which correctly always showed the preview window (since +d is default) unless -d was specified.

44RadiosityFeature RequestAllVery LowLowImprove Normals Handling in RadiosityTracked on GitHub
Future release Task Description

Currently, radiosity does not make use of the fact that pertubed normals would theoretically just require a different weighting of already-sampled rays, leading to the following issues:

  • Honoring normal pertubations in radiosity leads to an increased number of samples, slowing down sample cache lookup.
  • The increased number of samples is generated from a proportionally higher number of sample rays, slowing down pretrace even further.
  • Low-amplitude pertubations tend to be smoothed out; “reviving” these is only possible by increasing the general sample density.
  • Handling of multi-layered textures with different normal pertubations is currently poorly implemented.

As a solution, I propose to store for each radiosity sample not only the resulting illumination for a perfectly unpertubed normal, but from the same set of sample rays also compute the illumination for an additional set of about a dozen standardized pertubed-normal directions, and interpolate among these when computing the radiosity-based illumination for a particular point that has a pertubed normal.

For backwards compatibility, this method of dealing with pertubed normals in radiosity might be activated by a different value for the “normal” statement in the radiosity block, say, “normal 2”.

227Refactoring/CleanupUnimp. Feature/TODO3.70 RC3Very LowHighFixed Vector LimitationsTracked on GitHub
Task Description

See this documentation entry for more details.

50Runtime errorPossible Bug3.70 beta 32Very LowMediumFrequent segfaults with photon scenesTracked on GitHub
Task Description

I observe frequent segfaults with POV-Ray 3.7 betas when rendering scenes using photons:

  • Debian Linux 4.0r5 “etch” for AMD64
  • AMD Phenom X4 9650 2.3GHz, 6 GB RAM
  • POV-Ray compiled with Intel icpc 11.0

Segfaults are sporadic but frequent (occurring in roughly 50% of all photon renders).

151Runtime errorPossible Bug3.70 beta 37aVery LowLowNo way to cancel save while parsing, never ending error...Tracked on GitHub
Task Description

On Windows, when I try and save a file while it is being parsed prior to rendering, I get an error, “Failed to save file: The operation completed successfully”, with a single OK button to click. Despite the weird wording, I’m OK with that.

However after clicking OK I get the error, “Failed to save file ‘...’“, with three buttons: Cancel, Try Again, Continue. Not sure what “Continue” means in this context, given that the possibilities would seem to be covered by the other two buttons. Whatever.

Also, sometimes I get a message with only a single “Retry” button. Not sure what the exact message was.

Anyway, the real problem is that, regardless of which button I press, the program continues to spawning the same error message endlessly. Luckily there is a delay between them, but still it would be nice to have at least one of the three buttons *stop* POV-Ray from asking me again.

Also, once the program finishes parsing the file and it becomes possible once again to save the file, it does nothing. I.e. it doesn’t save the file. So what’s the point of the message and all the options? Why not just say, “Unable to save the file, file is parsing” and be done with it?

I think I recall the same behavior in 3.6.2, so it’s nothing new that’s been introduced.

79Source codeFeature Request3.70 beta 35aVery LowLowFull-Featured Test-Scene to check the correctness of po...Tracked on GitHub
Future release Task Description


it would be nice if there exists a test scene (not a benchmark) which has a high coverage of povray source and can be used as correctness validation of povray. It schould be produce an image which can be compared to a golden reference image.

It may be also possible to create a regression test suite which does automatic comparision of the render results.

4Subsurface ScatteringUnimp. Feature/TODO3.70 beta 32Very LowLowIntegrate Subsurface Scattering with standard lighting ...Tracked on GitHub
Future release Task Description

Subsurface Scattering still uses its own rudimentary code to compute illumination from classic light sources; this must be changed to use the standard light source & shadow handling code, to add support for non-trivial light sources (e.g. spotlights, cylindrical lights, area lights), partially-transparent shadowing objects etc.

196Subsurface ScatteringDefinite Bug3.70 RC3Very LowLowMore SSLT CaveatsTracked on GitHub
Future release Task Description

when a prism is differenced with a primitive (cylinder in this case) if sslt is used it causes a seq fault. Reference distribution file logo.inc and the Povray_Logo_Prism definition.

306Subsurface ScatteringDefinite Bug3.70 RC7Very LowHighfinish subsurface block before global_settings subsurfa...Tracked on GitHub
3.71 release Task Description

The following scene causes a crash:

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

global_settings {
  subsurface { }
96Texture/Material/FinishFeature RequestNot applicableVery LowLowUser-defined warpsTracked on GitHub
Future release Task Description

User-defined warps would be nice to have, something along the lines of:

warp {
  function { MyFnX(x,y,z) } // function to compute pattern-space x-coordinate from object-space <x,y,z> coordinate
  function { MyFnY(x,y,z) } // ditto for pattern-space y coordinate
  function { MyFnZ(x,y,z) } // ditto for pattern-space z coordinate

// a displacement warp:
warp {
  function { x + MyFnX(x,y,z) }
  function { y + MyFnY(x,y,z) }
  function { z + MyFnZ(x,y,z) }
115Texture/Material/FinishFeature Request3.70 beta 37aVery LowLowMore cutaway_texturesTracked on GitHub
Future release Task Description

Think this is still a problem. See the attached scene file. Find the WindowFrameSegment declaration for more info. The scene as-is shows the problem (SOME portions of the difference inherit the color of the room) the window opening is scaled larger to show that they AREN’T touching. The problem goes away when (in WindowFrameSegment) the 1st occurrence of the applied texture is commented out and the 2nd occurrence is uncommented, and cutaway_textures is commented out.

142Texture/Material/FinishFeature Request3.70 beta 37aVery LowLowcamera_view pigment from MegaPOVTracked on GitHub
Future release Task Description

I probably don’t have to explain why the camera_view pigment in MegaPOV was important, but I will list some reasons anyway:

1) post-processing could be performed in-scene
2) new types of focal blur effects could be created
3) feedback fractals were possible

I’m sure there are many others, as this is one of those features that has undetermined potential!

178Texture/Material/FinishFeature Request3.70 beta 39Very LowLowModify metallic reflection code to better work with con...Tracked on GitHub
Task Description

The combination of metallic reflection with conserve_energy causes the reflection to lose colour, as demonstrated by the following scene:

global_settings {
  max_trace_level 10

camera {
  right x*image_width/image_height
  location  <-2,2.6,-10>
  look_at   <0,0.75,0>

light_source {
  color rgb 1.3

sky_sphere {
  pigment {
    gradient y
    color_map {
      [0.0 rgb <0.6,0.7,1.0>]
      [0.7 rgb <0.0,0.1,0.8>]

plane {
  y, 0
  texture { pigment { color rgb 0.7 } }

#declare M=
material {
  texture {
    pigment {rgbt <1.0,0.7,0.2,0.99>}
    finish {
      ambient 0.0
      diffuse 0.5
      specular 0.6
      roughness 0.005
      reflection { 0.8, 1.0 metallic }
  interior { ior 1.5 }

box {
  <-0.2,0,-2.3>, <0.0,4,0.3>
  material { M }
  rotate z*5
  rotate x*2
183Texture/Material/FinishPossible Bug3.70 beta 40Very LowLowcutaway_textures broken with child unionsTracked on GitHub
Future release Task Description

When using cutaway_textures in a CSG object that has union children, results are not as expected; instead, surfaces in the union children that have no explicit texture will be rendered with the default texture instead. This is not the case for e.g. difference children.


#default { texture { pigment { rgb 1 } } }

camera {
  right x*image_width/image_height
  location  <0,1.5,-4>
  look_at   <0,1,0>

light_source { <500,500,-500> color rgb 1 }

#declare U = union {
  sphere { <0,-0.1,-1>, 0.3 }
  sphere { <0, 0.1,-1>, 0.3 pigment { color red 1 } }

intersection {
  sphere { <0,0,0>, 1 pigment { color green 1 } }
  object { U }
  rotate y*90

When declaring U as an intersection instead, the results are as expected, with the surface of the first sphere in U being rendered with the texture defined in the outer intersection.

256Texture/Material/FinishFeature Request3.70 RC6Very LowLowCSG texturing modesTracked on GitHub
Task Description

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.




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.

269Texture/Material/FinishPossible Bug3.70 RC6Very LowLowTransparent Objects inside Media Cause ArtefactsTracked on GitHub
Task Description

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.

286Texture/Material/FinishPossible Bug3.70 RC7Very LowLowreflection exponent other than 1 causes black artifacts...Tracked on GitHub
Task Description

[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)
    pretrace_end max(2,int(8/rad_lvl))/max(image_width,image_height)
    pretrace_end 32/max(image_width,image_height)
   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 {
  area_light <-300, 0, -300>, <300, 100, 300>, 3, 3
  rotate <-28, 0, 14>
  adaptive 0

 sphere { 0, 1
  texture {
    gradient y
     [.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

#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>

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
319Texture/Material/FinishFeature Request3.70 releaseVery LowLowAdd interior to #default directiveTracked on GitHub
Task Description

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

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

#include "my_predefined_materials.inc"

Default medias or IORs could also be useful.

334Texture/Material/FinishFeature Request3.70 releaseVery LowLowHLS colorsTracked on GitHub
Task Description

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.

20User interfaceFeature Request3.70 beta 32Very LowVery Lowrender window behaviorTracked on GitHub
Task Description

When changing the behavior of the render window, “Keep above main”, requires restarting the POV editor to take effect. It would be nice either to get a warning to restart, or to get it to work without restarting.

71User interfaceUnimp. Feature/TODO3.70 beta 34Very LowLowraise warning when command line option has no effectTracked on GitHub
Task Description

Warnings should be raised when a command line option has no effect,
for example...

pvengine +am

is legal, but without the number after it, it has no effect.

pvengine +am7

should be an error, and also raises no warnings.

138User interfaceFeature Request3.70 beta 37aVery LowLow"Rename" option in File menuTracked on GitHub
Task Description

Would be great if there were a “Rename” option in the editor File menu to rename the current file name. Otherwise, you have to close the file, rename it in file manager, then open the file again, thus loosing the current tab position and undo history for the file.

230User interfaceFeature Request3.70 RC3Very LowLowImproved handling of animationsTracked on GitHub
Task Description

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

Here a part of the video.ini file


# szenes based on games.pov

#Initial_Frame=450 - time scale 1000 - 30 seconds

#game-lost - time scale 1000 - 22 seconds

#game-lost - time scale 3000 - 12 seconds - fast through the night


#game-sunrise - time scale 1000 - 35 seconds

Now imagine all the problems:

One computer crashes often because of thermal problems.
Last picture rendere 487.

Now calculate the setings, that this computer continues the task at 487

Or 2 computers should render a scene.

Sounds very easy. Something like computer 1 makes 0..499 computer 2 makes 500..999.

But the computers are different in speed and the pictures are
very different in computation time.

So it would be best

computer 1: 0 to 999
computer 2: 999 to 0

They would meet in the middle, where ever this middle is.

So it would be much easier with

#game-sunrise - time scale 1000 - 35 seconds

So I have not to calculate the exact clock seting,
when a computer sould continue a task after crashing at picture 487

#game-sunrise - time scale 1000 - 35 seconds

This would be the reverse calcualtion order.
Starting with picture 1049 and going down 1048..1047

293User interfacePossible Bug3.70 RC7Very LowLowPOV-Ray Shown Twice in Windows TaskbarTracked on GitHub
Task Description

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?

295User interfaceDefinite Bug3.70 RC7Very LowLowMinor GUI BugsTracked on GitHub
Task Description

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.

311User interfacePossible Bug3.70 releaseVery LowLowElepsed time error on very long rendersTracked on GitHub
3.71 release Task Description

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.

323User interfacePossible Bug3.70 releaseVery LowVery LowTooltip for render speed status bar has wrong unitTracked on GitHub
Task Description

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.

328User interfaceDefinite Bug3.70 releaseVery LowMediumAscii char '=' in filenames causes command line parsing...Tracked on GitHub
Task Description

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.

333User interfaceFeature Request3.70 releaseVery LowLowMake text in "about" alt+b dialog selectable with the m...Tracked on GitHub
Task Description

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.

25AnimationDefinite Bug3.70 beta 32DeferLowPause sometimes fails when rendering animationTracked on GitHub
Task Description

There is an issue where the pause button in POVWIN will sometimes not work during an animation (primarily where the frame rate is high), and furthermore, POVWIN can then get into a state where it’s not possible to use the pause until it is re-started.

Newsgroup report.

87Geometric PrimitivesFeature RequestNot applicableDeferVery LowAdd new feature: Reference objectTracked on GitHub
Future release Task Description

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.

133Geometric PrimitivesFeature Request3.70 beta 37aDeferVery LowSubdivision supportTracked on GitHub
Future release Task Description

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


Would like to see this feature added natively to Povray.

243Geometric PrimitivesUnimp. Feature/TODOAllDeferLowSphere sweep behaves wrong when scaledTracked on GitHub
Future release Task Description

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.

281Geometric PrimitivesFeature Request3.70 RC7DeferLowBug in rendering of Bézier patchesTracked on GitHub
Future release Task Description

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:
[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> }


296Geometric PrimitivesDefinite Bug3.70 RC7DeferMediummax gradient computation is not thread safe (isosurface...Tracked on GitHub
3.71 release Task Description

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)

282Image formatFeature RequestNot applicableDeferLowUnrendered region should be transparent, not blackTracked on GitHub
Future release Task Description

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.

85OtherFeature RequestNot applicableDeferLowAspect ratio issuesTracked on GitHub
Future release Task Description


When rendering an image, there are actually three aspect ratios involved:

1) The aspect ratio of the camera, set with the up and right vectors.

2) The aspect ratio of the rendered image, set with the +W and +H parameters.

3) The aspect ratio of the pixels in the intended target medium. While this is very often 1:1, it’s definitely not always so (anamorphic images are common in some media, such as DVDs).

The aspect ratio of the camera does not (and arguably should not, although some people might disagree) define the aspect ratio of the image resolution, but the aspect ratio of the image as shown on the final medium. In other words, it defines how the image should be displayed, not what the resolution of the image should be.

This of course means that the aspect ratio of the target medium pixels has to be taken into account when specifying the image resolution. If the target medium pixels are not 1:1 (eg. when rendering for a medium with non-square pixels, or when rendering an anamorphic image eg. for a DVD), the proper resolution has to be specified so that the aspect ratio of the displayed image remains the same as the one specified in the camera block.

This isn’t generally a problem. It usually goes like “my screen is physically 4:3, so I design my scene for that aspect ratio, but the resolution of my screen is mxn which is not 4:3, but that doesn’t matter; I just render with +Wm +Hn and I get a correct image for my screen”.

However, problems start when someone renders an image using an image aspect ratio / pixel aspect ratio combination which does not match the camera aspect ratio. By far the most common situation is rendering a scene with a 4:3 camera for a screen with square pixels but with a non-4:3 resolution (most typically 16:9 or 16:10 nowadays). The image will be horizontally

In a few cases the effect is the reverse: The scene (and thus the camera) has been designed for some less-typical aspect ratio, eg. a cinematic 2.4:1 aspect ratio, but then someone renders the image with a 4:3 resolution. The resulting image will be horizontally squeezed.

In a few cases this is actually the correct and desired behavior, ie. when you are really rendering the image in an anamorphic format (eg. for a DVD). However, often it’s an inadverted mistake.

Some people argue that this default behavior should be changed. However, there are also good arguments why it should not be changed. Some argue that POV-Ray should have more features (at the SDL level, at the command-line level or both) to control this behavior.

There are several possible situations, which is why this issue is so complicated. These situations may include:

- The scene author doesn’t really care what aspect ratio is used to render the image, even if it means that additional parts of the scenery become visible or parts are cropped away when using a different aspect ratio than what he used.

In this case the choice of camera aspect ratio should be up to the person who renders the image, and thus selectable on the command-line. However, he should have an easy choice of how changing the aspect ratio affects the image: Should it extend the viewing range, or should it crop part of it, compared to the original?

And this, of course, while still making it possible to render for an anamorphic format.

- The author wants to support different aspect ratios, but he wants to control precisely how it affects the composition of the image. Maybe he never wants anything cropped away within certain limits, but instead the image should always be extended in whichever direction is necessary due to the aspect ratio. Or maybe he wants to allow cropping the image, but only up to a certain point. Or whatever.

In this case the choice of camera aspect ratio should be up to the author, and thus selectable in the scene file, while still allowing some changes from the command-line.

- The author designed his scene for a precise aspect ratio and nothing else, and doesn’t want the image to be rendered in any other aspect ratio. Maybe he used some very peculiar aspect ratio (eg. something like 1:2, ie. twice as tall as wide) for artistic composition reasons, and wants the image rendered with that aspect ratio, period.

Perhaps the author should be able to completely forbid the change of camera aspect ratio in the command-line.

Of course anamorphic rendering should still be supported for targets with a different pixel aspect ratio.

Possible solution

This solution does not necessarily address all the problems described above perfectly, but could be a good starting point for more ideas:

Add a way to specify in the camera block minimum and maximum limits for the horizontal and vertical viewing angles (and if any of them is unspecified, it’s unlimited). Of course for this to be useful in any way, there should also be a way to change the camera and pixel aspect ratios from the command line.

The idea with this is that the author of the scene can use these angle limits to define a rectangular “protected zone” at the center of the view, using the minimum angle limits. In other words, no matter how the camera aspect ratio is modified, the horizontal and/or vertical viewing angles will never get smaller than these minimum angles. This ensures that the image will never be cropped beyond a certain limit, only extended either horizontally or vertically to ensure that the “protected zone” always remains fully visible regardless of what aspect ratio is used.

The maximum angles can be used for the reverse: They ensure that no scenery beyond a certain point will ever become visible, no matter what aspect ratio is used. This can be used to make sure that unmodelled parts of the scene never come into view. Thus the image will always be cropped to ensure this, depending on the aspect ratio.

I’m not completely sure what should be done if both minimum and maximum angles are specified, and the user specifies an aspect ratio which would break these limits. An error message could be a possibility. At least it would be a way for the author to make sure his scene is never rendered using an aspect ratio he doesn’t want. He can use these angle limits to give some leeway how much the aspect ratio can change, to an extent, or he could even force a specific aspect ratio and nothing else (by specifying that both the minimum and maximum angles are the same).

So in short:

- Add a “minimum/maximum horizontal/vertical angles” feature to the camera block. These can be used to define a “protected zone” in the image which must not be breached by command-line options.

- Add a command-line syntax to change the camera aspect ratio (which automatically obeys the “protected zone” settings). Could perhaps give an error message if the command-line options break the limits in the scene camera.

- Add a command-line syntax to specify a pixel aspect ratio other than 1:1. This can be used to render anamorphic versions of the image on purpose (iow. not by mistake).

This can probably be made backwards-compatible in that if none of these new features are used, the behavior could be the same as currently (or at least similar).

242OtherFeature RequestAllDeferVery LowAlgorithm to fix the so-called shadow line artifactTracked on GitHub
Task Description

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.

245OtherFeature RequestAllDeferLowPOVMS message queue can fill up with GB of data for ver...Tracked on GitHub
Future release Task Description

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).

272OtherFeature Request3.70 RC6DeferVery LowMinor change, significant speedup in cubic polynomial s...Tracked on GitHub
3.71 release Task Description

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).

300OtherFeature Request3.70 RC7DeferVery LowReference Documentation SupportTracked on GitHub
Task Description

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)

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.

303OtherDefinite Bug3.70 RC7DeferVery Lowwrong bit depth reported for OpenEXR file formatTracked on GitHub
Task Description

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.

58Parser/SDLUnimp. Feature/TODO3.70 beta 32DeferLowallow SDL code to detect optional featuresTracked on GitHub
Task Description

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.

86Parser/SDLFeature RequestNot applicableDeferVery LowAdd support for more RNG typesTracked on GitHub
Future release Task Description

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

129Parser/SDLFeature Request3.70 beta 37aDeferVery LowHash arraysTracked on GitHub
Future release Task Description

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.

264PhotonsUnimp. Feature/TODO3.70 RC6DeferLowImprove precision of photon direction informationTracked on GitHub
Task Description

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.
8RadiosityUnimp. Feature/TODO3.70 beta 32DeferLowImprove Radiosity "Cross-Talk" Rejection in CornersTracked on GitHub
Future release Task Description

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.

98Refactoring/CleanupUnimp. Feature/TODO3.70 beta 36DeferMediumRefactor Windows UI code for Unicode supportTracked on GitHub
Future release Task Description

Windows UI code should be refactored to use _TCHAR throughout instead of char, as well as the corresponding string function macros, to head for Unicode support.

99Refactoring/CleanupUnimp. Feature/TODO3.70 beta 36DeferVery LowRefactor engine (front- & back-end) code for Unicode su...Tracked on GitHub
Future release Task Description

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

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