Elizabeth: Hello and welcome. I'm Elizabeth.
Chong: I'm Chong.
E: We're here today to use the PASCO Capstone software,
and talk about the feature of video analysis.
I've already started an experiment in Capstone,
and I have two graph displays and I've imported a movie.
The movie's been pre-recorded, but Chong's going to explain what the movie's about.
C: The movie is going to have a ballistic cart on a PASCO PAStrack,
which is bigger than the one that's shown here, moving,
and a ball shooting up out of it.
We're going to track the ball.
E: Let's see what the movie looks like. I'll go ahead and play it here.
There it is.
C: I notice, Elizabeth, that the movie's very slow.
E: It does appear very slow, almost as if it were slow motion.
Why is that?
C: That's because the video was shot using a high speed camera.
The other thing I notice is the cart caught the ball.
E: The cart did catch the ball. That's why we have this device.
This is meant to show the independence of motion in the X and Y direction.
If we are able to perhaps use our video analysis to show that,
that would be a great use for this tool.
C: Let's look at how do we go about correcting for the camera being a high speed camera.
E: Great idea. We can actually do that.
We can open up the properties in here, and we can go into the Movie Playback.
C: In this case, the video was filmed in 210 frames per second.
E: I'll enter 210 here instead of 29.
Now let's play that back and see if that looks different.
C: That looks more like real life.
E: That looks exactly like real life, exactly.
C: Perfect.
E: Now as Chong said, 210 frames per second.
We're going to end up clicking the mouse on the ball to track it.
If we work at 210 frames per second,
that's going to be a lot of clicks just to follow that little tiny ball.
C: Do we have a tool to address that?
E: We do in fact have a tool. We can address that.
Let's tell it to advance on each click, let's say seven frames.
We'll go into the properties and we'll do the same thing.
Actually, before we do that, we need to enter into video analysis mode. I'll do that.
In video analysis mode now, what I can do is back in the properties in the Overlay menu,
I can tell it instead of advancing every one frame, for it to advance seven.
Each mouse click will now be equal to seven frames.
C: Now that we corrected for time, is there any way that we can correct for distance?
If we wanted our data to be actually usable for real life.
E: That's a great idea. Real world data, yes. We have here a caliper.
It's draggable. You'll notice that when I click on either end of it, I can drag it.
The handy thing is, why don't you tell them about the length of the real track...
C: So the real track is exactly 1.2 meters.
We actually have something on the screen
that we can actually tell how big in video analysis it should be,
without actually even using a ruler.
E: Exactly. I've stretched the calipers to the length of the track.
Now all I have to go do is tell it what that length actually is in the real world.
I go into the properties and on the Calibration Tool,
when I open that up, I'm going to tell it that it's not 100 cm long.
It is actually 120 cm long. Let me type in 120.
Alright, so now it's calibrated in both space and time. I think we're ready to go.
C: Yes.
E: So now, it's the ball that we're going to be tracking.
I want to back up the video,
until that point where the ball is just about coming out of the cart.
There, I would say.
I'll maybe send it back. Alright.
I just can barely see the ball coming out of the cart.
C: I noticed the ball is quite small.
E: It's awfully small, Chong.
C: Is there a tool to help us see the ball better?
E: There is. They're called my glasses, so I'll put them on.
However, there is also a tool in the tool palette.
It's the magnify the video in the region of the cursor tool, which is one of my favorites.
What it does is just where I'm hovering the cursor, it actually magnifies that region.
I can just barely see the ball beginning to emerge from the cart.
When I click, it makes the movie active.
Now the next click is actually going to lay down a little digital breadcrumb there.
The next time I click...
C: I notice, Elizabeth, that you accidentally double-clicked two points together.
E: I did.
C: Is there a way for us to go back and correct that?
E: You know, after we finish this up,
we can absolutely go back and delete that or correct that point.
C: As Elizabeth is clicking, I just want to remind everybody,
there's actually additional instructions on how to use additional tools and the video analysis,
such as moving the X, Y graph, changing angles, using radius tools.
There are whole hosts of other features available on the PASCO web page.
E: I'm almost done with my clicking here because the ball is almost right back into the cart.
There I think it is. I'm going to give one last click where I know that ball just landed.
Now I'm going to turn off the magnify tool.
These little clicks that I have done now act exactly like sensor data.
What I have is some data that I could use to populate the graphs.
As we mentioned earlier, Chong, we are curious about whether or not
the motion in the X direction and the Y direction really are independent.
C: Yes. We would look for the X velocity versus time.
E: Let's look at the X velocity.
C: And the Y velocity versus time.
E: So the X velocity, I think, is right there.
C: Now it automatically put the time in.
E: It did actually put the time right there on the X axis. Now I'm looking for the Y velocity.
C: I noticed that the X velocity is a little jagged.
E: It is pretty jagged. But you know when I look at the Y axes of both of those plots,
they're not the same.
On the upper graph, it's a range from about 25 to about 55.
It's not anywhere where that range on the lower graph. What to do?
Well, luckily for us, Capstone has a neat little feature
that we can add a similar measurement to this graph.
I'm going to go ahead and add the X velocity down there.
X velocity, OK. There it is.
C: Now it looks a lot nicer.
E: Well, at least they're both in the same scale, and that's much better, I think.
I noticed something. What do you think about the slopes of those two plots of data?
C: They look pretty consistent. They look like it's not the same, but they're consistent...
E: The slopes aren't the same. They seem to be in great scale,
but they're not the same with one another.
It looks like the X velocity has a flat slope, whereas the Y velocity has a decreasing slope.
C: A decreasing slope.
E: So they have, wait a minute. That's amazing.
They have different slopes, so they had different velocities.
Yet the ball still landed back in the cart. What does that tell us?
C: That the ball was moving the same velocity as the cart in the X direction.
E: Exactly right. That's pretty amazing.
I'm sure there are all kinds of other things
that people would like to be able to do with video analysis,
which, as Chong mentioned, there is an instruction on how to do this,
as well as this video, available on the PASCO website.
We hope you'll go to the PASCO website and look for it.
We invite you to join us another time for another video.
Thank you very much.
C: Thank you for joining us.