Am 26.10.2014 10:22, schrieb Thomas de Groot:
> On 26-10-2014 9:54, Stephen wrote:
>> On 26/10/2014 08:13, Thomas de Groot wrote:
>>> But, it is the reason why on goggles, the baseline /is/ extended.
>>> Consider also those military stereoscopic viewers. From my own
>>> experience with stereoscopic viewers used for aerial photographs,
>>> extending the baseline makes objects appear like billboards.
>>
>> Would that not be more of the "telescopic" effect of the lens's used?
>>
> Hmm... I am not sure how much the lens influences the effect indeed. My
> guts tell me it is the baseline mostly, but then who would rely on his
> guts? :-)

Actually it is a combination of the telescopic effect of the lens - 
which enlarges the viewed objects in the horizontal and vertical - and 
the /absence/ of (sufficient) baseline extension - which would emphasize 
the depth cues accordingly.

For instance, in 20x binoculars I think you'd ideally need a baseline of 
around 12m; obviously this would make such devices very impractical to 
carry around, so that's not done.

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On 26-10-2014 14:19, clipka wrote:
> Am 26.10.2014 10:22, schrieb Thomas de Groot:
>> On 26-10-2014 9:54, Stephen wrote:
>>> On 26/10/2014 08:13, Thomas de Groot wrote:
>>>> But, it is the reason why on goggles, the baseline /is/ extended.
>>>> Consider also those military stereoscopic viewers. From my own
>>>> experience with stereoscopic viewers used for aerial photographs,
>>>> extending the baseline makes objects appear like billboards.
>>>
>>> Would that not be more of the "telescopic" effect of the lens's used?
>>>
>> Hmm... I am not sure how much the lens influences the effect indeed. My
>> guts tell me it is the baseline mostly, but then who would rely on his
>> guts? :-)
>
> Actually it is a combination of the telescopic effect of the lens -
> which enlarges the viewed objects in the horizontal and vertical - and
> the /absence/ of (sufficient) baseline extension - which would emphasize
> the depth cues accordingly.
>
> For instance, in 20x binoculars I think you'd ideally need a baseline of
> around 12m; obviously this would make such devices very impractical to
> carry around, so that's not done.
>
...but which is achieved for instance with aerial photographs used for 
cartographic photogrammetry, with baselines of hundreds of metres.

Thomas

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Am 26.10.2014 16:12, schrieb Thomas de Groot:
> On 26-10-2014 14:19, clipka wrote:
>> Am 26.10.2014 10:22, schrieb Thomas de Groot:
>>> On 26-10-2014 9:54, Stephen wrote:
>>>> On 26/10/2014 08:13, Thomas de Groot wrote:
>>>>> But, it is the reason why on goggles, the baseline /is/ extended.
>>>>> Consider also those military stereoscopic viewers. From my own
>>>>> experience with stereoscopic viewers used for aerial photographs,
>>>>> extending the baseline makes objects appear like billboards.
>>>>
>>>> Would that not be more of the "telescopic" effect of the lens's used?
>>>>
>>> Hmm... I am not sure how much the lens influences the effect indeed. My
>>> guts tell me it is the baseline mostly, but then who would rely on his
>>> guts? :-)
>>
>> Actually it is a combination of the telescopic effect of the lens -
>> which enlarges the viewed objects in the horizontal and vertical - and
>> the /absence/ of (sufficient) baseline extension - which would emphasize
>> the depth cues accordingly.
>>
>> For instance, in 20x binoculars I think you'd ideally need a baseline of
>> around 12m; obviously this would make such devices very impractical to
>> carry around, so that's not done.
>>
> ....but which is achieved for instance with aerial photographs used for
> cartographic photogrammetry, with baselines of hundreds of metres.

... and probably also far more than 20x zoom, right?

A billboard effect in objects is an indicator that the baseline is still 
a compromise.

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On 27-10-2014 15:34, clipka wrote:
> Am 26.10.2014 16:12, schrieb Thomas de Groot:
>> On 26-10-2014 14:19, clipka wrote:
>>> Am 26.10.2014 10:22, schrieb Thomas de Groot:
>>>> On 26-10-2014 9:54, Stephen wrote:
>>>>> On 26/10/2014 08:13, Thomas de Groot wrote:
>>>>>> But, it is the reason why on goggles, the baseline /is/ extended.
>>>>>> Consider also those military stereoscopic viewers. From my own
>>>>>> experience with stereoscopic viewers used for aerial photographs,
>>>>>> extending the baseline makes objects appear like billboards.
>>>>>
>>>>> Would that not be more of the "telescopic" effect of the lens's used?
>>>>>
>>>> Hmm... I am not sure how much the lens influences the effect indeed. My
>>>> guts tell me it is the baseline mostly, but then who would rely on his
>>>> guts? :-)
>>>
>>> Actually it is a combination of the telescopic effect of the lens -
>>> which enlarges the viewed objects in the horizontal and vertical - and
>>> the /absence/ of (sufficient) baseline extension - which would emphasize
>>> the depth cues accordingly.
>>>
>>> For instance, in 20x binoculars I think you'd ideally need a baseline of
>>> around 12m; obviously this would make such devices very impractical to
>>> carry around, so that's not done.
>>>
>> ....but which is achieved for instance with aerial photographs used for
>> cartographic photogrammetry, with baselines of hundreds of metres.
>
> ... and probably also far more than 20x zoom, right?

Yes, and I found this: 
http://www.nrcan.gc.ca/earth-sciences/geomatics/satellite-imagery-air-photos/air-photos/about-aerial-photography/9687

which explains it pretty well.

Thomas

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