Now if I only have available one

combination here when we talk about monocular vision.

All I am able to acquire is the projection of this Three-dimensional

motion onto the two-dimensional plane, let's call it x y plane.

If the camera's not calibrated, I'm not able to correspond,

for example, sizes from the image plane to the world.

So if for example this diameter of the ball is 20 pixels here and the image I do

not know what the size of the ball in the rear well is equal to how many centimeters

for example this diameter is Similarly we see that

intentionally you know at time t+1 here the ball

is Smaller than the ball at times T on the image plane and this is because the depth,

the distance of the ball from the image plane has changed.

So although I'm interested in estimating the motion

of objects in the three dimensional world All I'm

able to do with one camera is estimate the

motion of the objects in the two dimension world.

Again, if a calibrated camera were available,

and they also knew the geometry of

the scene, then I would be able to go from the 2D motion to

the 3D motion Similarly, if two or more cameras were available, I would be

able to find the depth in this scene with an escape factor, and so on.

However, for the better part of the course,

we'll only deal with one camera, as shown here.

And therefore, we'll deal with the estimation of the two dimensional motion.