I did know what you meant, and I wouldn't have said anything, except that you chose your words in contradiction to someone saying, "Once the ball leaves your hand, acceleration on the ball is essentially constant until it hits something." That is correct. You saying there is no acceleration is wrong.

http://xkcd.com/386/ >> ^ForgedReality:
Okay true enough, but now you're arguing semantics when you know full well what I meant.

It is true, but it is not just semantics.

Once the ball leaves the hand it will experience constant acceleration (ignoring drag). With just constant acceleration, the accelerometer can't tell us when the ball will reach apogee. Velocity and displacement are not being measured, so whether the ball is moving up or down won't register.

With only an accelerometer to work with, the only practical to way to predict when the ball will be at its highest point is to use the initial upward acceleration and a little bit of math.

>> ^ForgedReality:

>> ^messenger:
Nope. Once the ball leaves your hand, there is one significant acceleration force, which is gravity, downwards. There is no such force as "deceleration", just acceleration in a different direction. If by "deceleration" you mean gravity's acceleration downwards, it is constant enough for our purposes today: 9.8 m/s/s).>> ^ForgedReality:
>> ^blackoreb:
Your idea won't work. Once the ball leaves your hand, acceleration on the ball is essentially constant until it hits something. The only variable acceleration will be due to drag and "dependent on environmental influences such as air viscosity, temperature," etc.
The designer can account for your "never-let-go" scenario, as well as the more common "bouncing-around-in-the-back-seat" scenario, by requiring a minimum launch acceleration, followed by a minimum period of constant acceleration, before snapping a picture.
>> ^ForgedReality:
...Seems like it would make more sense to detect DEceleration, as that would facilitate either an upward OR a downward motion, and it wouldn't be reliant on possible bad guesses at when it would stop moving (dependent on environmental influences such as air viscosity, temperature, wind, obstacles in the path, etc)....

Once the ball leaves your hand, there IS no acceleration. In fact, it becomes inverted, as there are no longer any forces acting upon it to create acceleration, and it is now decelerating. Deceleration is not constant, as it reaches a point where it is essentially weightless. This is the point at which it currently seeks to snap the image. If It actually detected when the ball stopped moving, acceleration wouldn't be a factor.


Okay true enough, but now you're arguing semantics when you know full well what I meant.

>> ^messenger:

Nope. Once the ball leaves your hand, there is one significant acceleration force, which is gravity, downwards. There is no such force as "deceleration", just acceleration in a different direction. If by "deceleration" you mean gravity's acceleration downwards, it is constant enough for our purposes today: 9.8 m/s/s).>> ^ForgedReality:
>> ^blackoreb:
Your idea won't work. Once the ball leaves your hand, acceleration on the ball is essentially constant until it hits something. The only variable acceleration will be due to drag and "dependent on environmental influences such as air viscosity, temperature," etc.
The designer can account for your "never-let-go" scenario, as well as the more common "bouncing-around-in-the-back-seat" scenario, by requiring a minimum launch acceleration, followed by a minimum period of constant acceleration, before snapping a picture.
>> ^ForgedReality:
...Seems like it would make more sense to detect DEceleration, as that would facilitate either an upward OR a downward motion, and it wouldn't be reliant on possible bad guesses at when it would stop moving (dependent on environmental influences such as air viscosity, temperature, wind, obstacles in the path, etc)....

Once the ball leaves your hand, there IS no acceleration. In fact, it becomes inverted, as there are no longer any forces acting upon it to create acceleration, and it is now decelerating. Deceleration is not constant, as it reaches a point where it is essentially weightless. This is the point at which it currently seeks to snap the image. If It actually detected when the ball stopped moving, acceleration wouldn't be a factor.



Okay true enough, but now you're arguing semantics when you know full well what I meant.

Nope. Once the ball leaves your hand, there is one significant acceleration force, which is gravity, downwards. There is no such force as "deceleration", just acceleration in a different direction. If by "deceleration" you mean gravity's acceleration downwards, it is constant enough for our purposes today: 9.8 m/s/s).>> ^ForgedReality:

>> ^blackoreb:
Your idea won't work. Once the ball leaves your hand, acceleration on the ball is essentially constant until it hits something. The only variable acceleration will be due to drag and "dependent on environmental influences such as air viscosity, temperature," etc.
The designer can account for your "never-let-go" scenario, as well as the more common "bouncing-around-in-the-back-seat" scenario, by requiring a minimum launch acceleration, followed by a minimum period of constant acceleration, before snapping a picture.
>> ^ForgedReality:
...Seems like it would make more sense to detect DEceleration, as that would facilitate either an upward OR a downward motion, and it wouldn't be reliant on possible bad guesses at when it would stop moving (dependent on environmental influences such as air viscosity, temperature, wind, obstacles in the path, etc)....

Once the ball leaves your hand, there IS no acceleration. In fact, it becomes inverted, as there are no longer any forces acting upon it to create acceleration, and it is now decelerating. Deceleration is not constant, as it reaches a point where it is essentially weightless. This is the point at which it currently seeks to snap the image. If It actually detected when the ball stopped moving, acceleration wouldn't be a factor.

>> ^blackoreb:

Your idea won't work. Once the ball leaves your hand, acceleration on the ball is essentially constant until it hits something. The only variable acceleration will be due to drag and "dependent on environmental influences such as air viscosity, temperature," etc.
The designer can account for your "never-let-go" scenario, as well as the more common "bouncing-around-in-the-back-seat" scenario, by requiring a minimum launch acceleration, followed by a minimum period of constant acceleration, before snapping a picture.
>> ^ForgedReality:
...Seems like it would make more sense to detect DEceleration, as that would facilitate either an upward OR a downward motion, and it wouldn't be reliant on possible bad guesses at when it would stop moving (dependent on environmental influences such as air viscosity, temperature, wind, obstacles in the path, etc)....

Once the ball leaves your hand, there IS no acceleration. In fact, it becomes inverted, as there are no longer any forces acting upon it to create acceleration, and it is now decelerating. Deceleration is not constant, as it reaches a point where it is essentially weightless. This is the point at which it currently seeks to snap the image. If It actually detected when the ball stopped moving, acceleration wouldn't be a factor.

Your idea won't work. Once the ball leaves your hand, acceleration on the ball is essentially constant until it hits something. The only variable acceleration will be due to drag and "dependent on environmental influences such as air viscosity, temperature," etc.

The designer can account for your "never-let-go" scenario, as well as the more common "bouncing-around-in-the-back-seat" scenario, by requiring a minimum launch acceleration, followed by a minimum period of constant acceleration, before snapping a picture.

>> ^ForgedReality:

...Seems like it would make more sense to detect DEceleration, as that would facilitate either an upward OR a downward motion, and it wouldn't be reliant on possible bad guesses at when it would stop moving (dependent on environmental influences such as air viscosity, temperature, wind, obstacles in the path, etc)....

Congratulations! Your video, Throwable Panoramic Ball Camera, has reached the #1 spot in the current Top 15 New Videos listing. This is a very difficult thing to accomplish but you managed to pull it off. For your contribution you have been awarded 2 Power Points.

This achievement has earned you your "Golden One" Level 30 Badge!

>> ^Mojofreem:

If this was made by a German university group, why is it tagged Asia? Last I checked, Germany was still in Europe. Just sayin'.


First lines of the credits:

Throwable Panoramic Ball Camera
an Emerging Technologies demonstration at the
SIGGRAPH Asia 2011

(SIGGRAPH = Special Interest Group on GRAPHics, this is a convention of theirs)

I'd say you're right and the originating group is probably more important than where it is being demoed, but I think that (possibly plus the music) is the "why" on the Asia tag.

You can always toss it higher than the balcony, thus eliminating 30 posts about accelerometers and other witchcraft.

>> ^Trancecoach:

what if you dropped it?
from, say, a balcony?
does it take a picture from the highest point?

This was my guess at first. But their way relies on math, so that's alright.
>> ^rychan:

There's no freely movable parts inside the camera. The website makes it pretty clear:
"Our camera contains an accelerometer which we use to measure launch acceleration. Integration lets us predict rise time to the highest point, where we trigger the exposure."
So while your original post implies that it somehow detects the top of the trajectory as it happens, in fact the camera measures launch acceleration to predict the length of time until the top of the trajectory.
>> ^luxury_pie:
>> ^rychan:
>> ^luxury_pie:
^ I think it will take a photo everytime it stands still after being accelerated upwards. Using the fact that there will be no vertical forces applied to the "ballcamera" the moment it reaches maximum height after a throw.
engineering

Actually, no. The acceleration on the ball is roughly constant through the entire trajectory. So it's somewhat tricky to estimate when you're at the top of the parabola.

They seem to use an accelerometer to predict the time of max height as seen on
their website.
I wasn't referring to the acceleration rather to the forces, being applied while thrown, to a possible freely movable object inside of the camera, using the same principle as the seatbelt mechanism.
My train of thought leaves in a couple of minutes.

I wasn't aware of the explanation on the website while posting my first comment. The first part of my second comment covers that. The second part was to explain what I meant with "vertical forces applied to the ballcamera".
Sorry for the confusion.
Neat concept though, I'd like a bunch of these to create "panorama maps".

In reply to this comment by rychan:
There's no freely movable parts inside the camera. The website makes it pretty clear:
"Our camera contains an accelerometer which we use to measure launch acceleration. Integration lets us predict rise time to the highest point, where we trigger the exposure."

So while your original post implies that it somehow detects the top of the trajectory as it happens, in fact the camera measures launch acceleration to predict the length of time until the top of the trajectory.

>> ^luxury_pie:

>> ^rychan:
>> ^luxury_pie:
^ I think it will take a photo everytime it stands still after being accelerated upwards. Using the fact that there will be no vertical forces applied to the "ballcamera" the moment it reaches maximum height after a throw.
engineering

Actually, no. The acceleration on the ball is roughly constant through the entire trajectory. So it's somewhat tricky to estimate when you're at the top of the parabola.

They seem to use an accelerometer to predict the time of max height as seen on
their website.
I wasn't referring to the acceleration rather to the forces, being applied while thrown, to a possible freely movable object inside of the camera, using the same principle as the seatbelt mechanism.
My train of thought leaves in a couple of minutes.

There's no freely movable parts inside the camera. The website makes it pretty clear:
"Our camera contains an accelerometer which we use to measure launch acceleration. Integration lets us predict rise time to the highest point, where we trigger the exposure."

So while your original post implies that it somehow detects the top of the trajectory as it happens, in fact the camera measures launch acceleration to predict the length of time until the top of the trajectory.

>> ^luxury_pie:

>> ^rychan:
>> ^luxury_pie:
^ I think it will take a photo everytime it stands still after being accelerated upwards. Using the fact that there will be no vertical forces applied to the "ballcamera" the moment it reaches maximum height after a throw.
engineering

Actually, no. The acceleration on the ball is roughly constant through the entire trajectory. So it's somewhat tricky to estimate when you're at the top of the parabola.

They seem to use an accelerometer to predict the time of max height as seen on
their website.
I wasn't referring to the acceleration rather to the forces, being applied while thrown, to a possible freely movable object inside of the camera, using the same principle as the seatbelt mechanism.
My train of thought leaves in a couple of minutes.

http://hardware.slashdot.org/story/11/10/14/1840224/throwable-36-camera-ball-takes-spherical-panoramas

Combined with :




Non stop data analysis!!! We are watching you

>> ^rychan:

>> ^luxury_pie:
^ I think it will take a photo everytime it stands still after being accelerated upwards. Using the fact that there will be no vertical forces applied to the "ballcamera" the moment it reaches maximum height after a throw.
engineering

Actually, no. The acceleration on the ball is roughly constant through the entire trajectory. So it's somewhat tricky to estimate when you're at the top of the parabola.

They seem to use an accelerometer to predict the time of max height as seen on
their website.
I wasn't referring to the acceleration rather to the forces, being applied while thrown, to a possible freely movable object inside of the camera, using the same principle as the seatbelt mechanism.
My train of thought leaves in a couple of minutes.

>> ^luxury_pie:

^ I think it will take a photo everytime it stands still after being accelerated upwards. Using the fact that there will be no vertical forces applied to the "ballcamera" the moment it reaches maximum height after a throw.
engineering


Actually, no. The acceleration on the ball is roughly constant through the entire trajectory. So it's somewhat tricky to estimate when you're at the top of the parabola.