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The sphere_sweep autobounding either works pretty poorly or not at
all.
Consider following example (a single, very small object - either a
sphere_sweep or a cone - in the center of the image) and render it
with -UR (so user boundings are not removed), and with preview, if
possible. You'll notice the empty grey background renders pretty
slow. By uncommenting the USE_BOUNDING line to add an explicit
bounding or by uncommenting the USE_CONE line to replace the
sphere_sweep with some object with working autobounding you make the
render about 6x faster -- namely the background. This probably means
the sphere_sweep autobounding is broken (the object itself is so small
so that its own rendering time doesn't matter much).
//#declare USE_CONE = 1;
//#declare USE_BOUNDING = 1;
light_source { <-2, 5, -2> rgb 1 }
camera { location <-50, 0, 0> look_at <0, 0, 0> }
background { color rgb 0.4 }
#declare P1 = <0,-2,0>;
#declare P2 = <0,2,0>;
#declare R1 = 1;
#declare R2 = 0.1;
#ifdef (USE_CONE)
cone {
P1, R1, P2, R2
#else
sphere_sweep {
cubic_spline
5
P1 R1
(0.7*P1 + 0.3*P2) (0.7*R1 + 0.3*R2)
(0.5*P1 + 0.5*P2) (0.5*R1 + 0.5*R2)
(0.3*P1 + 0.7*P2) (0.3*R1 + 0.7*R2)
P2 R2
#end
pigment { colour rgb <0,1,0> }
#ifdef (USE_BOUNDING)
bounded_by { box { <-2,-3,-2>, <2,3,2> } }
#end
}
Yeti
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In article <slr### [at] monoceros physicsmunicz> ,
yet### [at] monocerosphysicsmunicz (David Necas (Yeti)) wrote:
> The sphere_sweep autobounding either works pretty poorly or not at all.
Are you sure you had autobounding on in the first place? If you take a look
at the render statistics you see only a minimal difference in the number of
intersection tests of the spheresweep object, so the bounding box clearly
works. Of course, as with all complex objects, the autobounding cannot always
determine the perfect bounding box due to the complexity of certain objects.
Thorsten
Render Statistics (autobounded)
Image Resolution 800 x 600
----------------------------------------------------------------------------
Pixels: 480000 Samples: 480000 Smpls/Pxl: 1.00
Rays: 480000 Saved: 0 Max Level: 1/5
----------------------------------------------------------------------------
Ray->Shape Intersection Tests Succeeded Percentage
----------------------------------------------------------------------------
Sphere Sweep 4147 412 9.93
Bounding Box 4537 4147 91.40
Light Buffer 297 297 100.00
Vista Buffer 480680 31960 6.65
----------------------------------------------------------------------------
Roots tested: 8294 eliminated: 0
Calls to Noise: 0 Calls to DNoise: 10
----------------------------------------------------------------------------
Shadow Ray Tests: 297 Succeeded: 0
----------------------------------------------------------------------------
Render Statistics (your manual bounding)
Image Resolution 800 x 600
----------------------------------------------------------------------------
Pixels: 480000 Samples: 480000 Smpls/Pxl: 1.00
Rays: 480000 Saved: 0 Max Level: 1/5
----------------------------------------------------------------------------
Ray->Shape Intersection Tests Succeeded Percentage
----------------------------------------------------------------------------
Box 4085 4085 100.00
Sphere Sweep 4085 412 10.09
Bounding Object 4085 4085 100.00
Bounding Box 4378 4085 93.31
Light Buffer 297 297 100.00
Vista Buffer 480677 31954 6.65
----------------------------------------------------------------------------
Roots tested: 8170 eliminated: 0
Calls to Noise: 0 Calls to DNoise: 10
----------------------------------------------------------------------------
Shadow Ray Tests: 297 Succeeded: 0
----------------------------------------------------------------------------
____________________________________________________
Thorsten Froehlich
e-mail: mac### [at] povrayorg
I am a member of the POV-Ray Team.
Visit POV-Ray on the web: http://mac.povray.org
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