Hello everyone and welcome back to competitive vision lecture series.

This is lecture 5 and part 4.

In this lecture we are going to talk about cameras and optics, how images are formed

and the first version of our camera called the pinhole camera.

So let us begin.

In this lecture, in this topic we are going to cover basically pinhole camera model, perspective

projection as well as some intrinsic and extrinsic camera parameters.

You already know what these are.

We have talked about vanishing points and vanishing lines before in our lectures and

they form part of, they are part of perspective projections.

We will look into it in the next part of this fifth lecture.

But for this part we talk about camera models.

So the first question that comes to our mind is what is a camera?

These days you go to Google and just search, right?

So what does it mean?

Camera means a room.

A room basically, so this is the oldest available evidence of a camera which is called camera

obscura, it was essentially a dark room inside a building like this on the right and through

a hole the light was allowed to pass and there was an image plane where this light was being

projected and a person could see on this image plane and basically, but it was a live camera

and this is how the image was captured from the real world.

Another application of a camera obscura was for tracing.

So a device like this, a pinhole, this is essentially a pinhole camera with an additional

reflector here, M reflector here.

It was used for actually tracing.

So you could see huge real world images inside this plane and you could easily trace them

using a paper and a trace.

So this is an example given of how you could trace it.

Going a bit ahead, so in order to improve tracing or in order to improve the paintings

or the sketches that you make, people used to come up with more sophisticated instruments

for capturing the real world information.

So here is a very good example, on the left is a painting by Johannes Vermeer called the

Music Lesson.

It is a painting done by this Dutch painter in the 17th century and on the right is a

documentary film by Tim Jenison.

He got curious, so Tim Jenison is a graphic artist.

He creates graphics for movies, he has his own company.

He got interested into the paintings by Johannes Vermeer essentially because he observed that

these paintings could not have been drawn live and he believed that, so there are certain

parts of the painting or the certain aspects of this painting that are not easily, that

are not live like they have to have been captured via an optical device or something like that.

So Tim on the right, he set up on a quest to solve this mystery and what he did was

he created or recreated the painting using the same texture and painting mechanisms in

this painting in a real world room and he used the same painting techniques and the

lightings and so on and so forth to recreate and then he would capture this image, sorry

he essentially recreated the painting of Johannes Vermeer.

The idea was to reverse engineer the process of the painting to recognize or at least do

a predictive analysis of what kind of optical device Johannes Vermeer used for capturing

this, for capturing this, for creating this painting.

It is very interesting if you are interested to know certain things about our certain interesting