COMPUTER GRAPHICS (XCS 354) UNIT – III

1. What is Transformation? 

Transformation is the process of introducing changes in the shape size and orientation of the object using scaling rotation reflection shearing & translation etc. 

2. Write short notes on active and passive transformations? 

In the active transformation the points x and x represent different coordinates of the same coordinate system. Here all the points are acted upon by the same transformation and hence the shape of the object is not distorted. In a passive transformation the points x and x represent same points in the space but in a different 

coordinate system. Here the change in the coordinates is merely due to the change in the type of the user coordinate system. 

3. What is translation? 

Translation is the process of changing the position of an object in a straight-line path from one coordinate location to another. Every point (x , y) in the object must || under go a displacement to (x,y). the transformation is: || x = x + tx ;y =y+ty 

4. What is rotation? 

A 2-D rotation is done by repositioning the coordinates along a circular path, in | the x-y plane by making an angle with the axes. The transformation is given by: X = r | cos (q + f) and Y = r sin (q + f). 

5. What is scaling? 

The scaling transformations changes the shape of an object and can be carried out by multiplying each vertex (x,y) by scaling factor Sx,Sy where Sx is the scaling factor of x and Sy is the scaling factor of y. 

6. What is shearing? 

The shearing transformation actually slants the object along the X direction or the Y direction as required.ie; this transformation slants the shape of an object along a required plane. 

7. What is reflection? 

The reflection is actually the transformation that produces a mirror image of an object. For this use some angles and lines of reflection. 

8. Distinguish between window port & view port? 

A portion of a picture that is to be displayed by a window is known as window port. The display area of the part selected or the form in which the selected part is viewed is known as view port.