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Am 12.01.2016 um 20:52 schrieb Mike Horvath:
> On 1/12/2016 2:17 PM, clipka wrote:
>> By /adding/ a "look_at" statement? ;)
>>
>> For starters you might get away ok without look_at.
>>
>> What you really need to do is translate the camera a bit to the left
>> (for the
>> left eye) or the right (for the right eye) -- which is actually a deal
>> easier if
>> you don't use look_at, because with that statement you'd have to
>> compute your
>> effective left/right axis "manually".
>
> Okay, but I was thinking that rotating by a small amount would be
> better. Otherwise the point of interest gets translated too. Should I
> use real-world measurements for the distance between the "eyes"?
>
>>>
>>> Also, is there a particular angle of view I should be aiming for?
>>
>> That depends on the (apparent) angle at which the image will be
>> visible using
>> that contraption.
>
> I don't understand what you mean. By angle of view I mean the camera
> angle. Is there some natural angle that is most like human vision?
It all depends on the contraption you use, and the size you print the
images at.
Let's forget about the stereoscope for a moment, and take a look at the
situation for a normal computer display. Suppose your display is WIDTH
cm wide horizontally, and you view it from a distance of DIST cm. The
display will occupy a certain portion of your field of vision, namely
ALPHA degrees in horizontally, where
tan (ALPHA/2) = (WIDTH/2) / DIST
Now for any image you display at full width on that computer display,
and view under the given parameters, the "natural angle that is most
like human vision" is exactly ALPHA.
With a stereoscope, the situation is more complex, because there are
lenses involved, so the /actual/ WIDTH and DIST parameters are of no use
-- you need to know the /apparent/ WIDTH and DIST, or the apparent ALPHA
itself. But the principle is always the same: The angle you want to
specify in POV-Ray is the horizontal angle that the image effectively
occupies in your field of view.
The lens also affects what camera type you should choose. With the
computer display, you want the default perspective camera; with the
spectroscope, you may want a more fisheye-like projection.
ultra_wide_angle projection may be ok for your purposes.
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On 1/12/2016 3:21 PM, Stephen wrote:
> A simple explanation at the beginning of this article.
>
> http://www.sky.com/shop/__PDF/3D/Basic_Principles_of_Stereoscopic_3D_v1.pdf
>
>
Thanks for that link. I will look at the StereoPhotoMaker software
documentation for more clues. I would like to rely on that software as
little as possible. Ideally I would do everything in POV-Ray and GIMP.
> Without getting arty ;) use between 40° and 60° that is roughly a 50mm
> lens.
>
Okay thanks.
> How are you going to drive your "Cardboard", what software?
>
>
I don't understand what you mean?
Mike
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On 1/12/2016 8:39 PM, Mike Horvath wrote:
> On 1/12/2016 3:21 PM, Stephen wrote:
>> A simple explanation at the beginning of this article.
>>
>> http://www.sky.com/shop/__PDF/3D/Basic_Principles_of_Stereoscopic_3D_v1.pdf
>>
>>
>>
>
> Thanks for that link. I will look at the StereoPhotoMaker software
> documentation for more clues. I would like to rely on that software as
> little as possible. Ideally I would do everything in POV-Ray and GIMP.
>
You can do it all in PovRay then combine the seperate images in
StereoPhotoMaker or similar.
>> Without getting arty ;) use between 40° and 60° that is roughly a 50mm
>> lens.
>>
>
> Okay thanks.
>
>> How are you going to drive your "Cardboard", what software?
>>
>>
>
> I don't understand what you mean?
>
Once you have made your 3d Stereo image. How are you going to use Google
Cardboard to view it? Or have you not got to that point yet?
I tried cardbord a few months ago and I think that downloaded a few demo
apps one had a gallery IIRC. Unfortunatly I've uninstalled tha apps and
can't remember which ones they were.
--
Regards
Stephen
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Am 12.01.2016 um 22:06 schrieb Stephen:
>>> How are you going to drive your "Cardboard", what software?
>>
>> I don't understand what you mean?
>
> Once you have made your 3d Stereo image. How are you going to use Google
> Cardboard to view it? Or have you not got to that point yet?
> I tried cardbord a few months ago and I think that downloaded a few demo
> apps one had a gallery IIRC. Unfortunatly I've uninstalled tha apps and
> can't remember which ones they were.
Judging from the article description, I /think/ his choice of software
is called "printer driver" ;)
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On 1/12/2016 4:06 PM, Stephen wrote:
> Once you have made your 3d Stereo image. How are you going to use Google
> Cardboard to view it? Or have you not got to that point yet?
> I tried cardbord a few months ago and I think that downloaded a few demo
> apps one had a gallery IIRC. Unfortunatly I've uninstalled tha apps and
> can't remember which ones they were.
>
I am not using Google Cardboard. I am going to print the pictures and
use this:
http://www.amazon.com/gp/product/B004EDB1S4?keywords=stereoscope&qid=1452568122&ref_=sr_1_90&sr=8-90
Mike
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> On 1/12/2016 2:17 PM, clipka wrote:
>> By /adding/ a "look_at" statement? ;)
>>
>> For starters you might get away ok without look_at.
>>
>> What you really need to do is translate the camera a bit to the left
>> (for the
>> left eye) or the right (for the right eye) -- which is actually a deal
>> easier if
>> you don't use look_at, because with that statement you'd have to
>> compute your
>> effective left/right axis "manually".
>
> Okay, but I was thinking that rotating by a small amount would be
> better. Otherwise the point of interest gets translated too. Should I
> use real-world measurements for the distance between the "eyes"?
Depending on your scene, and the location of the camera, rotating the
camera can result in uterly unreasonable offsets, like accidently
diverging camera axis or excessive convergence.
It's usualy beter to translate the camera /after/ you set the look_at
point for images like paysages or points of interest a fair distance
from the camera.
If the point of interest is close to the camera, then, it may beter to
translate the camera, then, set the look_at point at the same location
for both views. This correspond to the natural converging of the eyes
when looking to something close.
>
>>>
>>> Also, is there a particular angle of view I should be aiming for?
>>
>> That depends on the (apparent) angle at which the image will be
>> visible using
>> that contraption.
>>
>>
>
> I don't understand what you mean. By angle of view I mean the camera
> angle. Is there some natural angle that is most like human vision?
Yes, the camera's horizontal field ov fiew in degrees.
dependent on how the image is to be viewed.
>
>
> Mike
Alain
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On 1/12/2016 10:07 PM, Mike Horvath wrote:
> On 1/12/2016 4:06 PM, Stephen wrote:
>> Once you have made your 3d Stereo image. How are you going to use Google
>> Cardboard to view it? Or have you not got to that point yet?
>> I tried cardbord a few months ago and I think that downloaded a few demo
>> apps one had a gallery IIRC. Unfortunatly I've uninstalled tha apps and
>> can't remember which ones they were.
>>
>
> I am not using Google Cardboard. I am going to print the pictures and
> use this:
>
>
http://www.amazon.com/gp/product/B004EDB1S4?keywords=stereoscope&qid=1452568122&ref_=sr_1_90&sr=8-90
>
>
Oh! I saw "cardboard" in the title and jumped to conclusions. That makes
more sense now..
--
Regards
Stephen
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Mike Horvath <mik### [at] gmail com> wrote:
> On 1/12/2016 4:06 PM, Stephen wrote:
>
> I am not using Google Cardboard. I am going to print the pictures and
> use this:
>
>
http://www.amazon.com/gp/product/B004EDB1S4?keywords=stereoscope&qid=1452568122&ref_=sr_1_90&sr=8-90
>
A bit of trivia: There's another stereoscope on that Amazon page called the
'Owl' viewer-- designed by Brian May, the lead guitarist of the supergroup QUEEN
(!) Apparently, he is an avid 3D-stereoscope fan.
About 'convergence' of the two camera views: When I was younger, I did lots of
3D photo experiments, and found that the best 3D effect (for me at least) was to
have both camera views looking off into *infinity* (that is, no 'convergence' of
the cameras onto a nearer object) and to just move one of the cameras laterally
a couple of inches. This produced less eyestrain when viewing the 3D, and didn't
produce any 'odd' convergence-related perspective shifts of other objects in the
scene. In other words, I never converged the two cameras to look at a 'closer'
object, even if that object was the focus of attention.
Just my two-cents worth.
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"Kenneth" <kdw### [at] gmailcom> wrote:
>
> About 'convergence' of the two camera views: [clip]... I and found that the
> best 3D effect (for me at least) was to
> have both camera views looking off into *infinity* (that is, no 'convergence' of
> the cameras onto a nearer object) and to just move one of the cameras laterally
> a couple of inches. This produced less eyestrain when viewing the 3D, and didn't
> produce any 'odd' convergence-related perspective shifts of other objects in the
> scene...
Let me try and explain that a little better: Converging the two camera views
onto a nearer object can produce unwanted parallax shift of more distant objects
(at least in a real camera lens), the result being that those further-away
objects don't 'line up' correctly (and have unequal 'lens distortion') when
viewed in 3D-- especially when using a wide-angle lens setting. It's an odd
effect to describe, but it results in eye strain.
POV-Ray's typical perspective camera is essentially a 'pinhole' camera-- not
quite the same behavior as a real lens (the lens distortions are... different)
so it might be worth experimenting with 'convergent' views vs. non-convergence
views, to see if there is any real difference. I don't know; strange as it
sounds, I've never made a 3D scene in POV-Ray (!) It's now on my to-do list....
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> Let me try and explain that a little better: Converging the two camera views
> onto a nearer object can produce unwanted parallax shift of more distant objects
> (at least in a real camera lens), the result being that those further-away
> objects don't 'line up' correctly (and have unequal 'lens distortion') when
> viewed in 3D-- especially when using a wide-angle lens setting. It's an odd
> effect to describe, but it results in eye strain.
>
> POV-Ray's typical perspective camera is essentially a 'pinhole' camera-- not
> quite the same behavior as a real lens (the lens distortions are... different)
> so it might be worth experimenting with 'convergent' views vs. non-convergence
> views, to see if there is any real difference. I don't know; strange as it
> sounds, I've never made a 3D scene in POV-Ray (!) It's now on my to-do list....
>
>
>
>
Having a convergence can be beter, for cases when the center of interest
is close, less than 10 times the spacing of the cameras, and the
background don't contain far objects or is highly out of focus.
Think about 3D macro-photography. Very close, small, objects, tight area
of focal sharpness.
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