[Bf-cycles] Light leaks

David Black db4tech at yahoo.co.uk
Sun Apr 14 18:51:08 CEST 2013

Hi Brecht,

After carrying out several tests I have a question, is it possible that 
light leaks (see attached image) will slow down convergence performance 
with harder to find light sources due to extra calculations being 
performed?  It seems light leaks happen with all solid objects, this 
gets progressively worse whena Subsurf modifier is added, higher the 
subdivision modifier setting the more light penetration calculations are 
performed showing increasing light leaks. To help rule out recent code 
changes and SSS integration, tested with version 2.66a and 2.66.5.

*Cycles Light Leaks test Method:*
.    With the default scene, select Cycles render, delete the light
.    Add default material to the cube
.    Duplicate the cube and reduce in size (so it is inside the default 
cube), change the material so the smaller cube is a powerful emission source
.    Duplicate the main cube again and greatly enlarge, so it encompass 
all objects within the scene including camera, there should now be three 
cubes in the scene, each inside the other.
.    Select camera view and render several passes
.    Add a Subsurf modifier to the default main cube and re-render

To help reduce mailing list bandwidth, please find attached single 
image, will post a selection of test images showing progressive light 
leaks on blenderartists.org Brecht's Easter egg surprise thread.

Thank you for your time and great SSS coding work,



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