The Persistence of Vision Raytracer (POV-Ray).

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FS#203 - Radiosity artifacts at low error_bound

Attached to Project: POV-Ray
Opened by Andrey Zholos (aaz) - Thursday, 19 May 2011, 11:02 GMT
Last edited by Christoph Lipka (clipka) - Thursday, 21 June 2012, 22:51 GMT
Task Type Definite Bug
Category Backend → Radiosity
Status Closed
Assigned To Christoph Lipka (clipka)
Operating System All
Severity Low
Priority Normal
Reported Version 3.70 RC3
Due in Version 3.70 RC4
Due Date Undecided
Percent Complete 100%
Votes 0
Private No


A scene of a hollow sphere viewed from the inside:

difference {
    sphere { 0, 100 }
    sphere { 0, 99 }
    pigment { rgb 1 }
    finish { ambient .4 }

global_settings {
    radiosity {
        error_bound .1

Rendering produces dark splotches at the centers of the pretrace blocks, as shown in the attached image. Blocks rendered earlier have darker splotches. They also differ in shape between renders even with +HR (but not with +WT1).

Turning “always_sample” on, changing “pretrace_end” to 0.01, or increasing “count” past 1000 makes them imperceptibly faint (they can still be seen by increasing image contrast).

This is possibly a bug, as 3.6 doesn’t produce these artifacts regardless of additional settings.

povray.beta-test thread

This task depends upon

Closed by  Christoph Lipka (clipka)
Thursday, 21 June 2012, 22:51 GMT
Reason for closing:  Fixed
Additional comments about closing:  no news, so I guess the fix was effective
Comment by Christoph Lipka (clipka) - Thursday, 19 May 2011, 14:29 GMT

Closer analysis of the artifacts indeed revealed an implementation flaw in the radiosity code, which was introduced with change #5112. Working on a fix right now.

Comment by Christoph Lipka (clipka) - Thursday, 19 May 2011, 14:43 GMT
  • Field changed: Status (Assigned → Requires testing)
  • Field changed: Due in Version (Undecided → 3.70 RC4)
  • Field changed: Percent Complete (50% → 100%)

will be fixed with change #5438