And after you've seen the next slide, why does it make sense to transform the representation of scene points into a coordinate system where the camera is aligned with the z axis?

lucida

We have the camera aligned with the z axis because we use the z coordinate to do the homogenous divide. This makes sense because an object's depth or distance from the viewer should determine how we want to scale its x an y values. As objects move farther away, z gets larger and we divide x and y by a larger values, making the projected object smaller.

And after you've seen the next slide, why does it make sense to transform the representation of scene points into a coordinate system where the camera is aligned with the z axis?

We have the camera aligned with the z axis because we use the z coordinate to do the homogenous divide. This makes sense because an object's depth or distance from the viewer should determine how we want to scale its x an y values. As objects move farther away, z gets larger and we divide x and y by a larger values, making the projected object smaller.