POV-Ray

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.

Just like radiosity load/save, the photon mapping load/save mechanism should be moved to the frontend and controlled via command-line switch, instead of being SDL-driven in the backend.

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

See this documentation entry for more details.

The following scene causes a crash:

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

global_settings {
  subsurface { }
}

This is a list of unimplemented features and things to fix with respect to 3.7 vs 3.6 compatibility. They either need to be fixed in code, or failing that, to be documented prior to release.

Create_INI works differently from 3.6. Prior versions of POV-Ray would write all options to the file, even if they were not supplied by the user (non-supplied options would take the default value). Currently in 3.7, only supplied options are written, because the front-end does not send unused options to the back-end. The proper fix for this would be to have a set of defines that establish the defaults all in one place (currently we rely on hard-coded values scattered around the code), and for the Output_INI_Option() function to look up and use the default when not supplied. As this is not likely to be done before 3.7 release, we need to document it as a temporary situation.

The following messages are marked as ‘currently not supported by code’ in povmsgid.h. We need to check where this comment is correct and if so the docs need to be updated to indicate this (for items that are already documented). Some items may be re-implemented later, and some may never be:

• kPOVAttrib_TestAbort
• kPOVAttrib_TestAbortCount
• kPOVAttrib_VideoMode
• kPOVAttrib_Palette
• kPOVAttrib_DisplayGammaType
• kPOVAttrib_FieldRender
• kPOVAttrib_OddField
• kPOVAttrib_AntialiasGammaType
• kPOVAttrib_LightBuffer
• kPOVAttrib_VistaBuffer
• kPOVAttrib_DrawVistas

This bug should be edited to add/remove items as time goes by.

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.

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.

In the files bezier.cpp, fpmetric.cpp, fractal.cpp, hfield.cpp, isosurf.cpp, lathe.cpp, poly.cpp, polygon.cpp, prism.cpp, sor.cpp, and sphsweep.cpp the use of POV_MALLOC can be replaced by std::vector quite easily because the containing class already is a C++ class. As this is a low hanging fruit for continued code cleanup, it should be done sooner rather than later.

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

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)

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.

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.

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.

For proper render abort/continue support, radiosity cache data must be written to (or read from) disk even if the user does not explicitly opt to have a sample data file written/read. This feature has temporarily been dropped from 3.7 beta and is still pending re-implementation.

To meet high-reproducibility requirements in conjunction with SMP operation, it may be necessary to extend the 3.6 radiosity cache file format.

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.

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).

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.

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.

Most sample scenes and include files were designed at times when POV-Ray did not to any proper gamma handling, or still used the inferior 3.6 “assumed_gamma” mechanism.

All the scenes and include files should be reviewed, and updated to fit the new 3.7 gamma model.

The primary task will probably be gamma-adjusting literal color values and ambient parameters; I suggest using macros (which ideally should be defined in an include file) to be set according to the #version statement, so the scene/include file could be kept compatible with older versions.

The syntax notation used in the main documentation is different than that used in the quick-reference section. This should be changed for consistency, using the superior quick-reference notation throughout.

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.

The #debug message stream is only being flushed when it hits a newline character,
instead of after each #debug statement. This means that some final strings don’t show up.

#debug "This line prints,\n but this line doesn't."

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!

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.

This is a transparent box very close to a plane.

box {
    -1, 1
    pigment { rgbf <0, 0, 1, 1> }
}

plane {
    #if (version < 3.7)
        y, -1.0000007
    #else
        y, -1.00007
    #end
    pigment { rgb 1 }
    finish { ambient 1 }
}

camera {
    location <1, 2, 3>
    look_at 0
}

The box is placed 100 times closer to the plane for 3.6, but both 3.6 and 3.7 produce exactly the same black artifact (attached).

So apparently 3.7 is less accurate. (And the exact factor 100 feels suspicious.)

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.

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.

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> }

}

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.

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.

With previous versions of POV-Ray, it was possible to turn off display output, but still assess the output during render by viewing the output file as it was progressively generated. This allowed e.g. to run a long render on a remote machine as a background process, and check the output from time to time via FTP or similar.

The best time for a picture....

I set the day time and so the position of the sun by “clock=”

Normal I document my source very good, but this time,
I forgot the clock seting for the picture of my book cover.

So I would find it very practicall to put the clock value
and other setings for rendering
into EXIF data of the picture.

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.

Currently, fading light sources are used for lighting and shadow
calculations even when so far away as to no longer have any effect
on the outcome. The proposed solution is to add a new keyword
fade_cutoff_distance which tells povray to ignore the light
source when alluminating a point at larger distance.

A sample implementation is provided in the attached files. These
changes are still based on beta 34 as sources for the current beta
are not yet available, and starting to merge changes to beta 35
only at this time didn’t seem worth the effort. Also, please
disregard, changes in the CVS header comments (I also use
CVS locally for managing source files).

Further considerations regarding this feature:

- For special effects this feature can also be used if the light
source does not actually use fading. On the other hand, cutting
the light at some distances can be considered an extreme form
of fading which may justify the keyword name anyhow.

- Depending on how  FS#46  is implemented, the test for cutoff may
then be needed at another location as well.

- The default value currently is 0 (or *no* cutoff distance). For
#version 3.7 of higher, the default could be chosen automatically
based on the light source intensity and adc_bailout, although it
may then need to be overriden by the user for extreme pigments.

The following scene gives a comparison of current conserve_energy handling in standard shadow computations vs. photons.

Note how the rather highly reflective slabs fail to cast shadows, except where the photons target sphere enforces computation of shadow brightness to be done by the photons algorithm.

For more realistic shadowing without the need to enable photons, I suggest do add proper conserve_energy handling to the shadow computation code (which shouldn’t be too much effort).

global_settings {
  max_trace_level 10
  photons { spacing 0.003 media 10 }
}

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

light_source {
  <500,300,150>
  color rgb 1.3
  photons {
    refraction on
    reflection on
  }
}

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_Glass=
material {
  texture {
    pigment {rgbt 1}
    finish {
      ambient 0.0
      diffuse 0
      specular 0.2 // just to give a hint where the sphere is
    }
  }
  interior { ior 1.0 }
}

#declare M_PseudoGlass=
material {
  texture {
    pigment {rgbt 1}
    finish {
      ambient 0.0
      diffuse 0.5
      specular 0.6
      roughness 0.005
      reflection { 0.3, 1.0 fresnel on }
      conserve_energy
    }
  }
  interior { ior 1.5 }
}


sphere {
  <1.1,1,-1.3>, 1
  material { M_Glass }
  photons {
    target 1.0
    refraction on
    reflection on
  }
}

// behind target object
box {
  <-0.2,0,-2.3>, <0.0,4,0.3>
  material { M_PseudoGlass }
  rotate z*1 // just to better see the reflection of the horizon
}

// before target object
box {
  <2.4,0,-2.3>, <2.6,4,-0.3>
  material { M_PseudoGlass }
  photons { pass_through }
  rotate z*1 // just to better see the reflection of the horizon
}

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

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 } }
}

Adding full texture statement support to the background statement (with a scale of 1/1) aligned with the image_map direction of an image would allow i.e. specifying an image as background easily.

POV-Ray 3.6, upon encountering problems when parsing command line and/or .ini file options, would quote the offending option in the error message.

POV-Ray 3.7 currently just reports that there is some problem with the command line, without providing any details. I suggest changing this, as the information may be helpful at times.

Background

Possible solution

See Notepad++ or EditPad Lite for examples.

It would be nice to be able to drag tabs in the editor window to change their order, so as to group opened files together by relevance for instance.

I created an INI file which specifies the Input_File_Name, Output_File_Name, and also the Render_File and the remaining four text outputs as double-quoted absolute paths on my disk. When I run the render, I get the following output:

Preset INI file is ‘C:\USERS\TPREAL\DOCUMENTS\POV-RAY\V3.7\INI\QUICKRES.INI’, section is ‘[512×384, No AA]’.
Preset source file is ‘D:\Ruby\POV-Rb\ini\20110521_004037_Noix.ini’.
Rendering with 2 threads.
-
Cannot open file.
Render failed
-
CPU time used: kernel 0.06 seconds, user 0.02 seconds, total 0.08 seconds.
Elapsed time 0.52 seconds.

And the render does not start. The five text output files are not even created, and where the output image should be, there is a file with extension pov-state. The render works as it should only when I remove all five lines defining the five text output files. The paths I specify for the files are correct (paths exist and files do not, no white-spaces or anything), read/write restrictions are disabled in POV-Ray. This used to work in 3.6 and does not work now in 3.7 RC3. The error happens no matter if I run the render using GUI or command line.

(Also please note that the error message is really not useful here, it does not say which file it failed to open, and not even if it was an attempt to open for read or for write.)

I’d be really glad if you could correct this as it’s a critical functionality for me. I’m generating the POV-Ray code automatically and I need to parse the text output automatically to return the status to the generator.

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).

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.

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

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

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?