 |
|
|
|
|
|
| |
| |
|
|
|
|
| |
| |
|
|
I have noticed that heightfields sometimes present strange bugs which I can't
explain.
These bugs usually show up as small black areas in certain parts of the
heightfield. These areas are not shadows (no_shadow as no effect on them)
and they depend on the location of the camera (when the the heightfield is
looked from a bit different location, the size of these black areas change or
they disappear).
Here is an example. Although you can see the bug and the effect of moving
the camera by rendering individual frames with different values of the clock
(between 0 and 1), it's best viewed as an animation (some of the black areas
slowly diminish in size and disappear). Also from the animation it's clearly
seen that they are not shadows.
----------8<----------8<----------8<----------8<----------8<----------
camera
{ location y*.03*clock
look_at z*1
}
light_source { <90,90,0>, 1 }
height_field
{ function 900,900 { pattern { granite } }
smooth
scale <10,1.5,10>
pigment { rgb 1 }
translate -<5,.3,0>
no_shadow
}
----------8<----------8<----------8<----------8<----------8<----------
Any idea what causes these bugs?
(I can create a DivX animation if necessary.)
--
#macro M(A,N,D,L)plane{-z,-9pigment{mandel L*9translate N color_map{[0rgb x]
[1rgb 9]}scale<D,D*3D>*1e3}rotate y*A*8}#end M(-3<1.206434.28623>70,7)M(
-1<.7438.1795>1,20)M(1<.77595.13699>30,20)M(3<.75923.07145>80,99)// - Warp -
Post a reply to this message
|
|
| |
| |
|
|
|
|
| |
| |
|
|
Warp wrote:
> These bugs usually show up as small black areas in certain parts of the
> heightfield. These areas are not shadows (no_shadow as no effect on them)
> and they depend on the location of the camera (when the the heightfield is
> looked from a bit different location, the size of these black areas change
> or they disappear).
Hmmm... seems like "missing triangles" to me, they are very coincident
with triangles when you trace it big enough. Also, it seems it is something
to do with smooth, because I can't reproduce it without that keyword.
--
Jaime Vives Piqueres
La Persistencia de la Ignorancia
http://www.ignorancia.org
Post a reply to this message
|
|
| |
| |
|
|
|
|
| |
| |
|
|
I've not rendered yet, but if it really behaves the way, you describe,
then you can probably trace it down to some accuracy issue ...
--
[Talking about cardriving]
"People are opstacles?
Oh...I always treat them as bonus points..." [Ian Burgmyer in p.o-t]
// Jan Walzer <jan### [at] lzer net>
Post a reply to this message
|
|
| |
| |
|
|
|
|
| |
| |
|
|
Warp <war### [at] tagpovrayorg> schrieb in im Newsbeitrag:
3c4c251a@news.povray.org...
> I have noticed that heightfields sometimes present strange bugs which I
can't
> explain.
> These bugs usually show up as small black areas in certain parts of the
> heightfield. These areas are not shadows (no_shadow as no effect on them)
> and they depend on the location of the camera (when the the heightfield is
> looked from a bit different location, the size of these black areas change
or
> they disappear).
>
> Here is an example. Although you can see the bug and the effect of
moving
> the camera by rendering individual frames with different values of the
clock
> (between 0 and 1), it's best viewed as an animation (some of the black
areas
> slowly diminish in size and disappear). Also from the animation it's
clearly
> seen that they are not shadows.
>
> Any idea what causes these bugs?
>
I think that the normals are switched because it goes away if you add
double_illuminate.
--
#local T=text{ttf"timrom.ttf""Simon Adameit".01,0}#local Y=1;#while(Y>-1)
#local X=0;#while(X<7)#local O=trace(T<X,Y><X,Y>+z);cylinder{<X-3,Y,5>*.01
<X-3,Y,5>*.01+5e-3,5e-5pigment{rgb 25*O}}#debug chr(83-(O.x=0)*51)#local
X=X+.05;#end#debug"\n"#local Y=Y-.05;#end
Post a reply to this message
|
|
| |
| |
|
|
|
|
| |
| |
|
|
Jaime Vives Piqueres <jai### [at] ignoranciaorg> wrote:
: Hmmm... seems like "missing triangles" to me
Nope. If you render the animation (eg. 30 frames or more), you clearly see
that it's not a missing triangle which suddenly appears. The black spot
diminishes smoothly until it disappears.
--
#macro M(A,N,D,L)plane{-z,-9pigment{mandel L*9translate N color_map{[0rgb x]
[1rgb 9]}scale<D,D*3D>*1e3}rotate y*A*8}#end M(-3<1.206434.28623>70,7)M(
-1<.7438.1795>1,20)M(1<.77595.13699>30,20)M(3<.75923.07145>80,99)// - Warp -
Post a reply to this message
|
|
| |
| |
|
|
|
|
| |
| |
|
|
Jan Walzer <jan### [at] lzernet> wrote:
: I've not rendered yet, but if it really behaves the way, you describe,
: then you can probably trace it down to some accuracy issue ...
It's just that I can't figure out any reason why it happens.
If the spots were equal independently of camera location it would be
simpler.
--
#macro N(D)#if(D>99)cylinder{M()#local D=div(D,104);M().5,2pigment{rgb M()}}
N(D)#end#end#macro M()<mod(D,13)-6mod(div(D,13)8)-3,10>#end blob{
N(11117333955)N(4254934330)N(3900569407)N(7382340)N(3358)N(970)}// - Warp -
Post a reply to this message
|
|
| |
| |
|
|
|
|
| |
| |
|
|
Simon Adameit <gom### [at] gmxde> wrote:
: I think that the normals are switched because it goes away if you add
: double_illuminate.
That sounds like it would look the same independently of the camera location,
but it doesn't...
--
#macro N(D)#if(D>99)cylinder{M()#local D=div(D,104);M().5,2pigment{rgb M()}}
N(D)#end#end#macro M()<mod(D,13)-6mod(div(D,13)8)-3,10>#end blob{
N(11117333955)N(4254934330)N(3900569407)N(7382340)N(3358)N(970)}// - Warp -
Post a reply to this message
|
|
| |
| |
|
|
|
|
| |
| |
|
|
> That sounds like it would look the same independently of the camera
location,
> but it doesn't...
Then why does it disappear if you add double_illuminate ?
--
#local T=text{ttf"timrom.ttf""Simon Adameit".01,0}#local Y=1;#while(Y>-1)
#local X=0;#while(X<7)#local O=trace(T<X,Y><X,Y>+z);cylinder{<X-3,Y,5>*.01
<X-3,Y,5>*.01+5e-3,5e-5pigment{rgb 25*O}}#debug chr(83-(O.x=0)*51)#local
X=X+.05;#end#debug"\n"#local Y=Y-.05;#end
Post a reply to this message
|
|
| |
| |
|
|
|
|
| |
| |
|
|
>
> Any idea what causes these bugs?
Try this and you will see that the normals indeed seem to be switched.
camera
{ location #if(0) <0,-0.3,0> #else 0 #end
look_at z*1
}
height_field
{ function 200,200 { pattern { granite } }
smooth
scale <10,1.5,10>
pigment {slope y}
finish{ambient 1}
translate -<5,.3,0>
}
--
#local T=text{ttf"timrom.ttf""Simon Adameit".01,0}#local Y=1;#while(Y>-1)
#local X=0;#while(X<7)#local O=trace(T<X,Y><X,Y>+z);cylinder{<X-3,Y,5>*.01
<X-3,Y,5>*.01+5e-3,5e-5pigment{rgb 25*O}}#debug chr(83-(O.x=0)*51)#local
X=X+.05;#end#debug"\n"#local Y=Y-.05;#end
Post a reply to this message
|
|
| |
| |
|
|
|
|
| |
| |
|
|
Simon Adameit <gom### [at] gmxde> wrote:
: Then why does it disappear if you add double_illuminate ?
'double_illuminate' "fixing" it is a clear symptom that it has something
to do with normals, but what confuses me is that the normals should not
depend on camera location. If the object stays static and the light source
stays static and there's no phong/specular finish, the lighting should remain
the same regardless of the point of view.
--
#macro M(A,N,D,L)plane{-z,-9pigment{mandel L*9translate N color_map{[0rgb x]
[1rgb 9]}scale<D,D*3D>*1e3}rotate y*A*8}#end M(-3<1.206434.28623>70,7)M(
-1<.7438.1795>1,20)M(1<.77595.13699>30,20)M(3<.75923.07145>80,99)// - Warp -
Post a reply to this message
|
|
| |
| |
|
|
|
|
| |
|
|
