clipka <ano### [at] anonymousorg> wrote:

> Here are a few interesting observations:
>
> (1) The .020 render has no "Depth 1" samples (none stored at any rate).
> This is probably due to them being so dim that they're deemed irrelevant
> (think adc_bailout). Note how the number of "Depth 1" samples already
> decreases noticeably in the .021 render; the threshold is probably due
> to a combo of adc_bailout and surface brightness.
>

That got me thinking about the brightness levels in my test scene. (I didn't
take into account the relative darkness of shadows or pigment values etc.) SO, I
constructed a MUCH simpler test. From the looks of *this* code, no pixel in the
render falls below a certain 'middle brightness'-- maybe .3 or .4-- but the vast
render slowdown still occurs at the .020 rad-brightness 'threshold'. (BEWARE:
This scene renders *REALLY* slowly at the threshold-- 42 minutes, vs. 5 seconds
at a more normal rad brightness(!) Try reducing the number of boxes in the #for
loop; that *should* help somewhat.)

All very interesting! Uh, in some way.  ;-)

--------
#version 3.71; // beta 9

global_settings{
     assumed_gamma 1.0
     max_trace_level 5
     radiosity{brightness .020}  // or .021 for much faster render
     }
#default{finish{ambient .15 emission .3 diffuse .55}}

camera {
  perspective
  location  <-40, 90, -40>
  look_at   <70, 0,  70>
  right     x*image_width/image_height
  angle 40
}

light_source {
  0*x
  color rgb 1
  translate <500, 800, -500>
}

sky_sphere{pigment{rgb .7}}

plane{y,0  no_shadow
    pigment{rgb .4}
     }

#declare S = seed(119);
#for(i,1,900)
box{0,<1 + 4*rand(S),1 + 150*pow(.4*rand(S),2),1 + 4*rand(S)>
      translate 230*<rand(S),0,rand(S)>
      pigment{rgb 1}
      no_shadow
      }
#end
//----------------

The resulting 'threshold' render statistics (at a 640 X 480 render size, no
AA)...
----------------------------------------------------------------------------
Shadow Ray Tests:            217989   Succeeded:                     0
----------------------------------------------------------------------------
Radiosity samples calculated:           307805 (100.00 %)
Radiosity samples reused:                    0
Radiosity sample rays shot:           10773175
Radiosity octree nodes:                     10
Radiosity octree samples/node:        30780.50
Radiosity blocks examined:         46876375851
Radiosity blocks passed test 0:    46876375851 (100.00 %)
Radiosity blocks passed test 1:    19910334530 (42.47 %)
Radiosity blocks passed test 2:    19910334530 (42.47 %)
Radiosity blocks passed test 3:     7100384879 (15.15 %)
Radiosity blocks passed test 4:     5593912132 (11.93 %)
Radiosity blocks passed test 5:     5365165980 (11.45 %)
Radiosity blocks rejected:         41511209871 (88.55 %)
----------------------------------------------------------------------------
Radiosity Depth 0 calculated:           307805 (100.00 %)
Radiosity Depth 0 reused:                    0
Radiosity Depth 0 rays shot:          10773175
----------------------------------------------------------------------------
Radiosity (final) calculated:           307200 (100.00 %)
Radiosity (final) reused:                    0
Radiosity (final) rays shot:          10752000
----------------------------------------------------------------------------
  Pass     Depth 0           Total
----------------------------------------------------------------------------
  1            130             130
  2            475             475
  Final     307200          307200
----------------------------------------------------------------------------
  Total     307805          307805
  Weight     0.443
----------------------------------------------------------------------------
Peak memory used:          97529856 bytes
----------------------------------------------------------------------------
Render Time:
  Photon Time:      No photons
  Radiosity Time:   0 hours  0 minutes  0 seconds (0.015 seconds)
              using 2 thread(s) with 0.015 CPU-seconds total
  Trace Time:       0 hours 42 minutes 24 seconds (2544.042 seconds)
              using 2 thread(s) with 4608.830 CPU-seconds total

Post a reply to this message