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.
Attached to Project: POV-Ray
Opened by Andrey Zholos - 2011-11-05
Last edited by William F Pokorny - 2016-10-19
Opened by Andrey Zholos - 2011-11-05
Last edited by William F Pokorny - 2016-10-19
FS#226 - Near-coincident surface accuracy
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.)
near.png
Historical search (ignore case needed)
* Max_distance
* Small_tolerance
From comment in objects.cpp, a change occurred for >= MIN_ISECT_DEPTH
(no such limit in 3.6.1), or some postcondition in FindIntersection
For instance: in trace.cpp, the postcondition is := dist > SMALL_TOLERANCE
The post condition somehow contradict the comment about MIN_ISECT_DEPTH
I will try to experiment with the post condition later.
Post condition is not relevant for the original test scene.
But MIN_ISECT_DEPTH is !
at 1.0e-4 and 1.0.e-5, it's the picture of 3.7RC...
at 1.0e-6, back to the picture of 3.6
The comment (of objects.cpp) seems to ask for a less rough value than SMALL_TOLERANCE as MIN_ISECT_DEPTH, yet 1.0e-4 seems not small enough (compared to 1.0e-3 of SMALL_TOLERANCE).
Now tracked as github issue #125.