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All,
There is some debate going on whether the current implementation of
the fishey and omnimax camera types is correct. The following comes
from a bug report that was submitted quite sometime ago. The basic
question is whether the portal of the image should or should not
touch the sides of the image when rendered in a non one to one
aspect ration. This behavior can be fixed (with the fix supplied
in the original bug report) but we would like to hear your opinions
on the subject.
-----------------
Description:
There is code in render.c to scale these cameras according
to the aspect ratio of the camera; for instance
camera {
fisheye
location <0,0,0>
direction z
right x*1.33 // scale for 4:3 image
up y
}
If this is run with a 640x480 output image, it should make
a round image, touching the top and bottom, with black
space on left and right. In fact, it makes an elliptical image
which touches the frame edge on all 4 sides. When I say 'should'
I mean that this is how it is coded in render.c, as below, but
it does not work.
------------------------------------------------------------
--
Ken Tyler - POV-Ray Technical Assistance Group
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"Ken" wrote:
> There is some debate going on whether the current implementation of
> the fishey and omnimax camera types is correct.
I think they should be circular, i.e. not touch all four sides of the image,
except if the up and right vectors are equally long (omnimax should of
course never touch the bottom).
But I'd like to take the fisheye camera further. I'd like to be able to
specify the radius of the black border in degrees, so I can decide myself if
I want it to be small or large, or so large that it isn't visible in the
image at all. I'm fairly sure this is possible and not too hard to
implement. The angle could be specified right after the fisheye keyword.
I've always thought that the fisheye camera would be many times more
interesting if I could get that black border to disappear, and have the
scene fill out the entire view!
Rune
--
3D images and anims, include files, tutorials and more:
Rune's World: http://rsj.mobilixnet.dk (updated June 26)
POV-Ray Users: http://rsj.mobilixnet.dk/povrayusers/
POV-Ray Webring: http://webring.povray.co.uk
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Ken wrote:
>
> All,
>
> There is some debate going on whether the current implementation of
> the fishey and omnimax camera types is correct. The following comes
> from a bug report that was submitted quite sometime ago. The basic
> question is whether the portal of the image should or should not
> touch the sides of the image when rendered in a non one to one
> aspect ration. This behavior can be fixed (with the fix supplied
> in the original bug report) but we would like to hear your opinions
> on the subject.
I can only assume that since no one else has commented on this that
no one but Rune thinks that the current behavior is wrong.
Last chance for public comment...
--
Ken Tyler - POV-Ray Technical Assistance Group
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in news:3BA19B06.D5F42D76@pacbell.net Ken wrote:
> Last chance for public comment...
>
It's not a matter of right/wrong, it's a not (well) documented
feature. Why should raytracing stick to the possibilitys of
photography, where it can go beyond?
Why should a user want a circular image in a rectangle? To have black
areas to the left and right? Then he is in trouble, the same trouble
as the user that currently wants black areas above and beneath.
I can change the documentation to reflect the current behaviour. Maybe
a warning could be added to POV-Ray that informs the user that should
set the aspect ratio to 1 if he wants a circular image.
Ingo
--
Photography: http://members.home.nl/ingoogni/
Pov-Ray : http://members.home.nl/seed7/
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"ingo" wrote:
> It's not a matter of right/wrong
Yes it is. The fisheye camera type should be dependent on the up and right
vectors just like the other camera types.
> Why should a user want a circular image in a rectangle?
> To have black areas to the left and right? Then he is in
> trouble, the same trouble as the user that currently
> wants black areas above and beneath.
Not correct. If he has set 'up' to 'y' and 'right' to '4/3*x' then that is
what he want. If he sets both up and right to have a length of 1 then he
wants the
current behavior. The user should decide, not be forced to have it one way.
> I can change the documentation to reflect the current behaviour.
> Maybe a warning could be added to POV-Ray that informs the user
> that should set the aspect ratio to 1 if he wants a circular image.
But setting the aspect ratio to 1 (using up and right vectors) doesn't give
a circular image - that's the whole problem.
I think it should work this way for maximum flexibility:
If right is set to have a length of 1 then the ellipsoid will touch the left
and right border of the image. If right is set to have a length of 4/3 then
the ellipsoid will go out 3/4 out to the borders of the image. For
consistency, if right is set to have a length of less than one, then the
ellipsoid should go out further than the borders of the image. the up vector
should work the exact same way. This would also mean that you could set both
up and right to be less than one, and then the ellipsoid will go further out
than the borders in all directions. If you set up and right to be small
enough you can get rid of the black borders entirely.
That would be consistent and allow for maximum flexibility and control.
Rune
--
3D images and anims, include files, tutorials and more:
Rune's World: http://rsj.mobilixnet.dk (updated June 26)
POV-Ray Users: http://rsj.mobilixnet.dk/povrayusers/
POV-Ray Webring: http://webring.povray.co.uk
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On Fri, 14 Sep 2001 23:44:05 +0200, Rune wrote:
>But setting the aspect ratio to 1 (using up and right vectors) doesn't give
>a circular image - that's the whole problem.
But it does give a circular image. It just doesn't look circular on your
monitor because you have square pixels. As has been noted before: aspect
ratio and image size ratio are only the same on some media.
--
#macro R(L P)sphere{L F}cylinder{L P F}#end#macro P(V)merge{R(z+a z)R(-z a-z)R(a
-z-z-z a+z)torus{1F clipped_by{plane{a 0}}}translate V}#end#macro Z(a F T)merge{
P(z+a)P(z-a)R(-z-z-x a)pigment{rgbf 1}hollow interior{media{emission 3-T}}}#end
Z(-x-x.2x)camera{location z*-10rotate x*90normal{bumps.02scale.05}}
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"Ron Parker" wrote:
> But it does give a circular image. It just doesn't look
> circular on your monitor because you have square pixels.
> As has been noted before: aspect ratio and image size
> ratio are only the same on some media.
You have missed the point. What I'm talking about has nothing to do with the
actual resolution of the image, but about the aspect ratio set using the up
and right vectors. The point is that you should be able to get a circular
fisheye even if your image isn't square (again, "square" has nothing to do
with the actual resolution, but about the aspect ratio set using the up and
right vectors).
This has always been the philosophy with other camera types such as
perspective and orthographic, so why should fisheye not follow that?
Remember that my proposed solution does not remove any functionality, only
expand.
Rune
--
3D images and anims, include files, tutorials and more:
Rune's World: http://rsj.mobilixnet.dk (updated June 26)
POV-Ray Users: http://rsj.mobilixnet.dk/povrayusers/
POV-Ray Webring: http://webring.povray.co.uk
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In article <3ba28233@news.povray.org> , "Rune" <run### [at] mobilixnet dk>
wrote:
> "Ron Parker" wrote:
>> But it does give a circular image. It just doesn't look
>> circular on your monitor because you have square pixels.
>> As has been noted before: aspect ratio and image size
>> ratio are only the same on some media.
>
> You have missed the point. What I'm talking about has nothing to do with the
> actual resolution of the image, but about the aspect ratio set using the up
> and right vectors. The point is that you should be able to get a circular
> fisheye even if your image isn't square (again, "square" has nothing to do
> with the actual resolution, but about the aspect ratio set using the up and
> right vectors).
>
> This has always been the philosophy with other camera types such as
> perspective and orthographic, so why should fisheye not follow that?
> Remember that my proposed solution does not remove any functionality, only
> expand.
Hmm, at least to me it is not clear how you think it should behave. Could
you post two small images, one that shows how it works now and one edited
(obviously not rendered) version of it that shows how you think it should
look like?
Thorsten
____________________________________________________
Thorsten Froehlich, Duisburg, Germany
e-mail: tho### [at] trfde
Visit POV-Ray on the web: http://mac.povray.org
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"Thorsten Froehlich" wrote:
> Hmm, at least to me it is not clear how you think it should behave.
> Could you post two small images, one that shows how it works now
> and one edited (obviously not rendered) version of it that shows
> how you think it should look like?
See povray.beta-test.binaries
Rune
--
3D images and anims, include files, tutorials and more:
Rune's World: http://rsj.mobilixnet.dk (updated June 26)
POV-Ray Users: http://rsj.mobilixnet.dk/povrayusers/
POV-Ray Webring: http://webring.povray.co.uk
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In article <3ba4b182@news.povray.org> , "Rune" <run### [at] mobilixnetdk>
wrote:
> "Thorsten Froehlich" wrote:
>> Hmm, at least to me it is not clear how you think it should behave.
>> Could you post two small images, one that shows how it works now
>> and one edited (obviously not rendered) version of it that shows
>> how you think it should look like?
>
> See povray.beta-test.binaries
Thanks. I agree with you that the shown output is the way it should work.
However, I am not sure this will/can be changed in 3.5. We will see...
Thorsten
____________________________________________________
Thorsten Froehlich, Duisburg, Germany
e-mail: tho### [at] trfde
Visit POV-Ray on the web: http://mac.povray.org
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