Since the focal length is in millimeter, so we have to convert every thing in millimeter in order to calculate it. Suppose an image has been taken of a person 5m tall, and standing at a distance of 50m from the camera, and we have to tell that what is the size of the image of the person, with a camera of focal length is 50mm. We can better understand this, with this example.įor example Calculating the size of image formed The second angle that is formed is:įrom this equation, we can see that when the rays of light reflect back after striking from the object, passed from the camera, an invert image is formed. Where minus denotes that image is inverted. Now there are two different angles formed in this transform which are represented by Q. Z = distance between object and the camera Now we will explain this concept mathematically. Thats how a 3d scene is transformed into 2d, with image of pixels. Each pixel has a value of pixel co ordinates. It is used to describe how 3d points are mapped in a 2d image plane. It is not a 3d coordinate system, rather it is a 2d system. Camera coordinate frameĬamera co-ordinate frame is used to relate objects with respect of the camera. World coordinate frame is used for co-relating objects in a 3 dimensional world. For example, checking if a particular object is in a proper place with respect to the other object. Object coordinate frame is used for modeling objects. In order to analyze a 3d world/image/scene, 5 different frame of references are required. We will start this discussion by the concept of frame of reference: Frame of reference:įrame of reference is basically a set of values in relation to which we measure something.

We will see in detail about why this happens, that those objects which are near to you look bigger, while those who are far away, look smaller even though they look bigger when you reach them. The same principle on which human vision works and the same principle on which the camera works.

So overall, the perspective transformation deals with the conversion of 3d world into 2d image.

Whereas transformation is the transfer of an object e.t.c from one state to another. This is called perspective in a general way. When human eyes see near things they look bigger as compare to those who are far away.

2d to 3d conversion image processing