|
 |
Sorry for my poor english!
The Last message not clearly, so I described my problem again.
In my study, the result images have been divided into four parts, namely, bright
objects, shaded objects, bright background and shaded background. source
light's azimuth and zenith angle be fixed,When the camera to change the azimuth
and zenith angle, the four components will be changed.
The interaction of light and objects, including reflection and transmission.In
my study ,When the light through objects, Divided into two cases :1
through a layer object, objects should be bright ;2 through two or more
layers objects are shaded. But now,pov-ray can not distinguish between the two
cases. I have tried 'filter' and 'tansmit' , but the results unsatisfactory.
How to solve this problem?
Thanks a lot!
Post a reply to this message
|
|
|
|
"andy Wang" <wjg### [at] yahoo comcn> wrote in message
news:web.484363b26a6f8b3135072ccd0@news.povray.org...
>
> Sorry for my poor english!
>
> The Last message not clearly, so I described my problem again.
>
> In my study, the result images have been divided into four parts, namely,
> bright
> objects, shaded objects, bright background and shaded background. source
> light's azimuth and zenith angle be fixed,When the camera to change the
> azimuth
> and zenith angle, the four components will be changed.
>
> The interaction of light and objects, including reflection and
> transmission.In
> my study ,When the light through objects, Divided into two cases :1
> through a layer object, objects should be bright ;2 through two or more
> layers objects are shaded. But now,pov-ray can not distinguish between the
> two
> cases. I have tried 'filter' and 'tansmit' , but the results
> unsatisfactory.
> How to solve this problem?
>
> Thanks a lot!
>
Hi Andy,
The question is still not totally clear, but you show good persistence :-).
A couple of things that you may like to clarify:
o Where you refer to 'planes' in your original post, are these POV-Ray
planes (with a single infinite surface) or are they more like sheets of
glass with two surfaces?
o You show planes b and c being side-by-side, which, if they overlap, may
be giving you problems with concurrent surfaces.
o Your diagram shows the light shining straight into the camera, which will
not work very well.
What I suspect you want is to have a bright object or a bright background
that can be filtered by the 'planes' (see the example code below), then you
will actually 'see' the light coming off that bright object.
I'm not sure if either of these is the question you're asking, but ...
a) If you want to block out all light shining through more than one object
you could set the max_trace_level to be quite small (e.g. 3). Light arriving
at the camera that has passed through too many surfaces will then be
completely blocked and the pixel will appear black.
b) If you want to progressively reduce the amount of light getting through
to the camera, based on how many objects the light has passed through, then
you may need to increase max_trace_level (maybe try 10) and set a relatively
high transmit value on each object. For example using a transmit value of
0.9 would cut out just 10% of the light as it passes through each surface.
Light passing through 4 surfaces would therefore be 60% as bright as light
that hadn't passed through any.
Otherwise you may wish to post a small snippet of code that illustrates your
problem.
Here's a small but complete scene that may help you to express your problem:
camera {location <0,0,-1> look_at 0}
//global_settings { max_trace_level 3 }
// A Bright object
sphere {<0,0,3>,1
pigment {rgb <1,1,0>}
finish {ambient 1}
}
// Top left quadrant
box {<0,0,0>,<-1,1,0.01>
pigment {rgbt <1,1,1,0.9>}
}
// Bottom left quadrant
box {<0,0,0>,<-1,-1,0.01>
pigment {rgbt <1,1,1,0.9>}
finish {ambient 0}
}
// Bottom left quadrant (further away)
box {<0,0,0>,<-1,-1,0.01>
translate z*0.02
pigment {rgbt <1,1,1,0.9>}
finish {ambient 0}
}
// Bottom right quadrant
box {<0,0,0>,<1,-1,0.01>
translate z*0.02
pigment {rgbf <1,0,0,1>}
finish {ambient 0}
}
Note that there is no light source in this scene, just a sphere with ambient
set to '1'. The bottom left quadrant is masked by two boxes, so appears
dimmer than the top left quadrant which is only masked by one. The bottom
right quadrant is masked by a red filter.
If you uncomment the max_trace_level setting you should see the bottom left
quadrant turn black, because light from the sphere would need to trace 5
tracks to pass through the 4 surfaces to get to the camera.
Regards,
Chris B.
Post a reply to this message
|
|
