POV-Ray

Dear PovRay maintainers and developers, congratulations for your great RayTracer!

We think that we have found a bug while we were rendering a piece of cloth.

In this piece of cloth were defined two textures, one for one side and one for the another side:

  texture { mesh_tex0_0 }
  interior_texture { mesh_tex0_1 }

• Please: Look at line 77414 of the attached file “test.pov” to see

these definitions in their original context.

We have found some artifacts in the final rendering, in concrete near some wrinkles,
please, look at the attached file “render_artifacts.tga”, I have painted a big green arrow
near the artifacts, maybe you’ll need to do a zoom to see them more accurately.

They are as though the texture of the other side was painted in the incorrect side.

Fortunately, we have a patch to fix this bug (thanks to Denis Steinemann, he made the
implementation for PovRay 3.5, so I have adapted these changes to release 3.6.1)

Although we have found this bug in the Windows and Linux 3.6.1 releases,
the patch was generated in Linux (using the source code release of “povray-3.6.1”).

To apply this patch, inside the parent folder of the directory “povray-3.6.1” execute:

            patch -p0 < other_side_artifacts.patch

And the “povray-3.6.1” will be patched and you will get a console output like this:

 patching file povray-3.6.1/source/lighting.cpp
 patching file povray-3.6.1/source/mesh.cpp
 patching file povray-3.6.1/source/render.cpp

We don’t know if this “hack” is enough smart to apply in the next release,
but we think that it fixes the bug (the artifacts dissapear).

Best regards and thank you very much for your great RayTracer!

POV-Ray does not follow common practice on command-line handling; for instance:

povray +i"My File"

entered on a Unix shell would be passed to POV-Ray as

povray
+iMy File

(each line representing a distinct parameter here), which POV-Ray would further dissect, interpreting it as

povray
+iMy
File

To achieve the desired effect, one would actually have to quote the string twice:

povray +i"'My File'"

which the shell would translate to

povray
+i'My File'

which POV-Ray would interpret as

povray
+iMy File

In both cases, this is obviously not what a Unix user would expect.

The further dissecting of individual command-line parameters may have had its valid roots in the peculiarities of DOS’ command-line handling, but to my knowledge all major contemporary operating systems follow a concept akin to Unix, passing a list of parameters instead of a monolithic command line, and burdening the respective command shells with the task of dissecting command lines into parameters.

Therefore I suggest to disable this anachronistic feature in favor of contemporary standards; a compiler flag might be used to allow for easy re-enabling of the feature, for compiling POV-Ray on exotic targets.

- edit -

It has been pointed out that the described behaviour differs from 3.6, so I’m promoting this to a bug and changing the title.

Using prisms in intersecion or difference CSG objects may cause artifacts in POV-Ray 3.6.2 as well as 3.7.0.beta.34, as demonstrated by the following code:

camera {
  right    -x
  up        y*image_height/image_width
  location  <-24,19,12>
  look_at   <0,0,0>
}

light_source { <100,200,100> color rgb 1 }

plane { y, -2 pigment { color rgb 1 } }


#declare KeyValue = 1.366; // pick any you like

difference {
  prism {
    linear_sweep -0.5,0.5, 4
    
    <-3,20-17>,
    <-3,KeyValue>,
    <-6,-3>,
    <-0,-5>
  }
  intersection {
    cylinder { <-7,-0.51,1>, <-7, 0.51,1>, 4.0 }
    plane { z, KeyValue }
  }
  pigment { color rgb 0.5 } 
}

Apparently the surface of the other object becomes visible when it exactly coincides with a vertex of the prism; probably there is a failure of the inside() test for such values.

I’m running POV-Ray for (64 bit) Windows v3.62 on (64 bit) Windows Vista

This pov file:

#include "colors.inc"
#include "metals.inc"

light_source { <6, 9, -21> color White }
camera { location <0, 0, -3> look_at <0, 0, 0> }

sphere_sweep {
                cubic_spline
                6
                <-2.0, 0, 0> 0.05

                <0.000,0,0> 0.2
                <0.025,0,0> 0.2
                <0.050,0,0> 0.2
                <0.075,0,0> 0.2

                <3.0,0,0> 0.2
                pigment { color White }
}

Produces two strange artifacts: A disk at the center of the sweep, and a faint “halo” or veil which shows as 4 faint hyperbolas centered around the origin.

I have tried tweaking tolerance (for no other reason than I saw that someone else was tweaking it to solve a problem) but this does not seem to change things.

For a look at MY result when I run this, view this image:

Alain reports the same behavior in the latest version: “It’s still there with the latest version: 3.7 beta 35a.” This MAY move the status to “confirmed”, but I can’t do that

Someone else says that changing the scale (!) “solves” the problem by moving the disk and the halo offscreen, but that sounds like a bad idea to me.

-Jeff Evarts, first-time POVRay bug reporter

I understand that some things have changed in the way certain computations in POV-Ray decide when something is “good enough” and I think this is biting me in Julia_Fractal (where, of course, the highest-resolution computations are needed).

The bug has been posted here:

http://news.povray.org/povray.bugreports/thread/%3Cweb.4dbf2e26b56a53c15b4449250%40news.povray.org%3E/

Including a short .pov file and instructions that reproduce it.

(It pops up in other configurations and view angles as well, but this one captures in in a way that makes it clear it’s a bug: the distance of the camera from the origin appears to change the shape of the rendered object).

This appeared first on a Windows Server 2003 machine, it is apparently confirmable on at least one other system as per that thread.

The problem arises when I am trying to trace a radiosity scene without conventional lighting that has a GSG merge object. There are a coincident surfaces, but these surfaces are first merged, then the texture applied. The texture is a simple solig color non-transfluent pigment, default normal, default finish etc..

Problem consists when adding antialiasing, changing resolution, changing camera view-point etc.; when I replace merge with union, the problem disappeared.

The scene was checked on two different machines with different versions of POV-Ray:

1. Gentoo Linux, kernel 2.6.39-r3, i686 Intel(R) Xeon(TM) CPU 2.80GHz GenuineIntel, 2G RAM (this is Dell PowerEdge 2650 server with 2 dual-core Intel Xeon MP processors); Persistence of Vision™ Ray Tracer Version 3.7.0.RC3 (i686-pc-linux-gnu-g++ 4.5.3 @ i686-pc-linux-gnu)
2. Gentoo Linux, kernel 2.6.37-r4, x86_64 AMD Athlon™ X2 Dual Core Processor BE-2350, 2G RAM (non-branded machine); Persistence of Vision™ Ray Tracer Version 3.6.1 (x86_64-pc-linux-gnu-g++ 4.4.4 @ x86_64-pc-linux-gnu)

(scene has been adapted slightly to be rendered with 3.6, the adaptation was to change “emission” with “ambient” and replace gamma “srgb” with “2.2”)

Both machines generate similar images.

The attachment is an archive containing sources of minimal scenes with these problems, and sample pictures I generated from them on my machines.

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.

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

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.

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.

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)

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.

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.

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.

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.

With 3.7.0 final, rendering attached files (for Computer Engineering college course),
which renders without issues in povray 3.6.1, fails with following error:

...
==== [Rendering...] ========================================================
povray: backend/lighting/radiosity.cpp:324: virtual void pov::RadiosityFunction::BeforeTile(int, unsigned int): Assertion `(pts >= PRETRACE_FIRST) && (pts <= PRETRACE_MAX)' failed.

Command line:

povray +K0.6500 \
+FN +Q9 +MB1 \
+W600 +H400 \
+AM1 +A0.0 +R2 \
+D +SP32 +EP4 \
+L/usr/share/povray-3.7/include \
+Imain.pov \
+Omain-0.6500.png

Using Arch Linux testing current:
Linux archmidi 3.12.0-1-ARCH #1 SMP PREEMPT Wed Nov 6 09:06:27 CET 2013 x86_64 GNU/Linux

Downstream bug report:
https://bugs.archlinux.org/task/37689

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

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

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

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

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

example images rendered on win32 XP

#version 3.7;

global_settings {
 ambient_light 0
 assumed_gamma 1
}

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

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

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


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

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

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

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.

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.

User reported documentation inconsistency. Investigation led to the discovery of a bug in the setting of the current default value.

~source/frontend/renderfrontend.cpp reports the value “3” while ~source/backend/scene/scene.cpp sets a default value of “1”

Before for addressing this issue, are there any thoughts as to what the default value should be?