How to explain ... and results of poll

[Jaja]

Hello David SL,

Thanks, that's a good explanation.
We all agree it's an illusion - but why an illusion (the white streakes).
Now you explained that also ... ;-)

Kind regards,
Jaja
http://www.belgiumdigital.com

Nice pictures in the latest poll!

The train image can be explained by recognizing a few facts:

The train and your camera plane were moving foward, everything else
relative to your panned camera frame and the train was moving
backward.
Had the train not been there, your relative motion (toward the
left) with respect to the surrounding stationary objects would have
caused them to blur toward the left ( as they do.) This gives the
illusion that those stationary objects are moving from left to
right (which relative to your motion from right to left) they are.
Now add the train, which you are tracking (as best you can from
right to left) by panning so that it maintains its position in your
frame. If your motion relative to the train is near zero (as it
would be if you are panning at its foward rate of motion) then
relative to your camera frame its not moving. (no blur streaks) The
only blur affect visible, is the one contributed by the surrounding
non moving objects previously explained. Thus, your eye is tricked
into grouping the train with those blur streaks and thus gives the
illusion that the train is moving backward. Enhancing the illusion
are the streaks behind the train, which seem to be made by the
train..but upon close inspection reveal themselves to be part of
whatever stationary background was whizzing by from left to right
behind the train.

Knowing this, you should be able to reproduce the affect pretty
easily. Note, the affect is enhanced by a larger relative motion
between the tracked object and the stationary background components.

Dsl

Hello all,

First the results of the poll series 32. Here's the winner:



A nightshot of a church in Oostende (Belgian coast).
The complete results are online also and so is the new poll, series
33.
You're invited to vote again. Thanks for participation.

Now a question. When you look at image 3 of the new poll, there's
something strange going on. It's a panning shot of a train moving
forward, but the blurred background gives the impression it's
moving backwards ...
I took the image by following the train that drove from right to
left (panning also from right to left). Any explanation, or is it
an "optical illusion"?
When I showed the image for the first time, this was also discussed
but no reasonable explanation was found ...

Jaja
http://www.belgiumdigital.com

 

[Matt Grayson]

The important accident is that there was a light colored background object at about the train window's height and size. So the backward swoosh of the stationary object looks like it's a contrail off of the train's window. If it hadn't fit the train so well, we would probably filter it out from our internal motion-sensing image processing software.

Brilliant photos, Jaja,

Matt

Thanks, that's a good explanation.
We all agree it's an illusion - but why an illusion (the white
streakes).
Now you explained that also ... ;-)

Kind regards,
Jaja
http://www.belgiumdigital.com

Nice pictures in the latest poll!

The train image can be explained by recognizing a few facts:

The train and your camera plane were moving foward, everything else
relative to your panned camera frame and the train was moving
backward.
Had the train not been there, your relative motion (toward the
left) with respect to the surrounding stationary objects would have
caused them to blur toward the left ( as they do.) This gives the
illusion that those stationary objects are moving from left to
right (which relative to your motion from right to left) they are.
Now add the train, which you are tracking (as best you can from
right to left) by panning so that it maintains its position in your
frame. If your motion relative to the train is near zero (as it
would be if you are panning at its foward rate of motion) then
relative to your camera frame its not moving. (no blur streaks) The
only blur affect visible, is the one contributed by the surrounding
non moving objects previously explained. Thus, your eye is tricked
into grouping the train with those blur streaks and thus gives the
illusion that the train is moving backward. Enhancing the illusion
are the streaks behind the train, which seem to be made by the
train..but upon close inspection reveal themselves to be part of
whatever stationary background was whizzing by from left to right
behind the train.

Knowing this, you should be able to reproduce the affect pretty
easily. Note, the affect is enhanced by a larger relative motion
between the tracked object and the stationary background components.

Dsl

Hello all,

First the results of the poll series 32. Here's the winner:



A nightshot of a church in Oostende (Belgian coast).
The complete results are online also and so is the new poll, series
33.
You're invited to vote again. Thanks for participation.

Now a question. When you look at image 3 of the new poll, there's
something strange going on. It's a panning shot of a train moving
forward, but the blurred background gives the impression it's
moving backwards ...
I took the image by following the train that drove from right to
left (panning also from right to left). Any explanation, or is it
an "optical illusion"?
When I showed the image for the first time, this was also discussed
but no reasonable explanation was found ...

Jaja
http://www.belgiumdigital.com

 

[Jaja]

Hello Matt,

Thanks.
And yes, our brains often are mislead by what we see (or think we see ;-)
And the fact that a camera can capture that is also great ...

I guess it this was just a lucky shot that demonstrates perfectly what an illusion can be.

Jaja
http://www.belgiumdigital.com

Brilliant photos, Jaja,

Matt

Thanks, that's a good explanation.
We all agree it's an illusion - but why an illusion (the white
streakes).
Now you explained that also ... ;-)

Kind regards,
Jaja
http://www.belgiumdigital.com

Nice pictures in the latest poll!

The train image can be explained by recognizing a few facts:

The train and your camera plane were moving foward, everything else
relative to your panned camera frame and the train was moving
backward.
Had the train not been there, your relative motion (toward the
left) with respect to the surrounding stationary objects would have
caused them to blur toward the left ( as they do.) This gives the
illusion that those stationary objects are moving from left to
right (which relative to your motion from right to left) they are.
Now add the train, which you are tracking (as best you can from
right to left) by panning so that it maintains its position in your
frame. If your motion relative to the train is near zero (as it
would be if you are panning at its foward rate of motion) then
relative to your camera frame its not moving. (no blur streaks) The
only blur affect visible, is the one contributed by the surrounding
non moving objects previously explained. Thus, your eye is tricked
into grouping the train with those blur streaks and thus gives the
illusion that the train is moving backward. Enhancing the illusion
are the streaks behind the train, which seem to be made by the
train..but upon close inspection reveal themselves to be part of
whatever stationary background was whizzing by from left to right
behind the train.

Knowing this, you should be able to reproduce the affect pretty
easily. Note, the affect is enhanced by a larger relative motion
between the tracked object and the stationary background components.

Dsl

Hello all,

First the results of the poll series 32. Here's the winner:



A nightshot of a church in Oostende (Belgian coast).
The complete results are online also and so is the new poll, series
33.
You're invited to vote again. Thanks for participation.

Now a question. When you look at image 3 of the new poll, there's
something strange going on. It's a panning shot of a train moving
forward, but the blurred background gives the impression it's
moving backwards ...
I took the image by following the train that drove from right to
left (panning also from right to left). Any explanation, or is it
an "optical illusion"?
When I showed the image for the first time, this was also discussed
but no reasonable explanation was found ...

Jaja
http://www.belgiumdigital.com

 

[David SL]

Jaja,

No problem, it turns out those years I spent in undergraduate physics courses actually do have some use! Yay !

Dsl

Thanks, that's a good explanation.
We all agree it's an illusion - but why an illusion (the white
streakes).
Now you explained that also ... ;-)

Kind regards,
Jaja
http://www.belgiumdigital.com

Nice pictures in the latest poll!

The train image can be explained by recognizing a few facts:

The train and your camera plane were moving foward, everything else
relative to your panned camera frame and the train was moving
backward.
Had the train not been there, your relative motion (toward the
left) with respect to the surrounding stationary objects would have
caused them to blur toward the left ( as they do.) This gives the
illusion that those stationary objects are moving from left to
right (which relative to your motion from right to left) they are.
Now add the train, which you are tracking (as best you can from
right to left) by panning so that it maintains its position in your
frame. If your motion relative to the train is near zero (as it
would be if you are panning at its foward rate of motion) then
relative to your camera frame its not moving. (no blur streaks) The
only blur affect visible, is the one contributed by the surrounding
non moving objects previously explained. Thus, your eye is tricked
into grouping the train with those blur streaks and thus gives the
illusion that the train is moving backward. Enhancing the illusion
are the streaks behind the train, which seem to be made by the
train..but upon close inspection reveal themselves to be part of
whatever stationary background was whizzing by from left to right
behind the train.

Knowing this, you should be able to reproduce the affect pretty
easily. Note, the affect is enhanced by a larger relative motion
between the tracked object and the stationary background components.

Dsl

Hello all,

First the results of the poll series 32. Here's the winner:



A nightshot of a church in Oostende (Belgian coast).
The complete results are online also and so is the new poll, series
33.
You're invited to vote again. Thanks for participation.

Now a question. When you look at image 3 of the new poll, there's
something strange going on. It's a panning shot of a train moving
forward, but the blurred background gives the impression it's
moving backwards ...
I took the image by following the train that drove from right to
left (panning also from right to left). Any explanation, or is it
an "optical illusion"?
When I showed the image for the first time, this was also discussed
but no reasonable explanation was found ...

Jaja
http://www.belgiumdigital.com