 Hello, and welcome to the video lecture on functions of graphic software. At the end of this session, students will be able to apply CAD fundamentals as well as advanced manufacturing technology to industry problems. The following topics will be discussed in this particular video lecture. Step of first session which was about input and output devices and the second topic about the functions of graphic software. Input devices, so what are input devices? So whenever we work with a computer, we need to enter data and instructions to the computer using some devices. These devices are called input devices. These devices convert data and instructions to a form that can be recognized by the computer. So we'll be discussing some of the input devices. First one, keyboard. Keyboard, it's the most commonly used input device. It allows data entry into a computer system by pressing a set of keys neatly mounted on a keyboard. It contains some extra command keys and function keys that affect the operation of computer or keyboard itself. There are different types of keyboard, standard keyboard, multimedia keyboard, wireless keyboard. So it's basically used in graphics to provide screen coordinates, menu selection, gaming controls and for entering many graphic functions. The second input device is mouse. The basic principle on which a mouse works is that you have a ball and under the ball we have XY transducers which are fixed. So these are basically let's say X and Y variable resistors. As a result of this, if you move the mouse in the X direction, the resistance of the X variable resistor will change. If you move it in the Y direction, the resistance of the Y variable resistor will change and the resistance is then taken as a measure of the position of the mouse. Now let us discuss the third input device that is the tracker ball. The tracker ball is there almost next to the keyboard and you can change the orientation of the ball and that changes the position of the cursor on the screen. Joystick. I move the stick in either direction, the resistors fixed at the bottom, the resistance changes and their position can be seen on the screen. Light pen. In a light pen, you have a light sensitive diode which is used to point onto the screen. From this pen, we can pick items from the menu. We can directly point your item on the menu and click that. Normally if you have a mouse, you are moving the mouse on the pad or on a board. In this, you don't have to do that. In this, you just take the pen and point it onto the screen and click it there. This basically works on a principle of sensing the light signal over there and current position of the screen is then sent back to the computer or to the CPU. The way it works is let's say we will be talking about raster graphic devices. In raster graphic devices, there is an electron gun that starts from one corner and spans the full screen like this at a rate of about 40 times a second or 50 times a second. It will be spanning the full screen. That means the gun starts from one corner and goes to the right. Come back to the left corner again and goes to the right and so on. So the moment the light pen senses the light over here, it knows how much time lag is there between starting point and this point. And that time lag is used to compute the total distance traveled and hence the position of the light pen at that point. This is how the position of the light pen is sensed and fed back to the machine. So this is the basic principle of a light pen. Output Devices. These are the devices which show output to the user. Example printer. Today we will be discussing about the plotter as the output devices. A plotter is a printer designed for printing vector graphics. Instead of printing individual dots on the paper, plotter draws continuous lines. This makes plotter ideal for printing architecture blueprints, engineering designs and other cad drawings. So we will be discussing about the flatbread plotter and drum plotter. In a flatbread plotter we have a table on which sheet of paper is fixed. Now on this sheet of paper we will have a set of pens. You can see the pens are mounted on the corner. The pens can move in the x and y direction. So the pens will be mounted on a carriage and they can move in the x and y direction and the paper is fixed. So if you want to make a drawing of a A4 size we will take a paper of A4 size, fix it on this plotter and the pens will move in the x and y directions. For moving the pens in the x direction we have a x drive motor and for moving the pens in the y direction we will have a y drive motor and as the pen is moving we need a mechanism to either lower the pen for drawing it or to raise it so that no line is drawn during the motion. So we have a pen raise and lower mechanism. So in this case essentially a paper is fixed on to the table and the pen can move in the x and y direction. Drum plotter. In the case of a drum plotter we have a drum. On this drum the paper is fixed. The paper can hang on both the sides and the paper is fixed on this. The drum can rotate by the rotation of drum we get motion in the y direction and the pens can move in the x direction. So the x direction motion is given by let's say an x drive motor and the y direction motion is given by drum motor and of course we have mechanism to raise and lower the pen. The basic advantage of this is it takes less space and the total moment of the pen is much less and typically these plotters are faster. The disadvantage is costing is high. Cost of maintenance is also high. Now let's discuss about functions of graphic software. Graphic software permits the interaction between the user and the systems while doing this graphic software is expected to perform various kinds of functions. So this functions it may include the generation of graphical elements with desired shape and size orientation and finally displaying on the screen. So this different kind of function can be combined in the following five functional groups. Generation of graphic elements which may be 2D and 3D. Graphical entity is sketching elements like dots, line, circle, arc, triangle, etc. Graphical entities are called 2D drawings. It also consists of different tools like trim, mirror, rotation, scale which will edit different graphical elements. 3D the primitive word mainly used for three dimensional elements like spear, cube, prism, pyramid, cylinder, etc. Second point that is transformation. Transformation mainly consists of editing or changing the given geometrical element or drawing or image which is displayed on the screen. Transformation are mainly used for geometrical element so that to construct or develop application model. This transformation mainly consists of the scaling which is nothing but enlargement or reduction of element, translation, reposition of image, rotation, providing angle to image. The third point that is display control and windowing functions. This function provides the user with the ability to view the image from the desired angle and at the desired magnification. This may include rotation of screen or view moving, zoom in and zoom out. Use of hidden lines will provide user and system to achieve extra better understanding of image. But if with the help of hidden lines drawing is getting complex then we should remove the hidden lines. With the help of transformation tools we can edit or change the geometrical entity. This function will provide options for replace, delete, modify portions of image. At last it will give provision to store image in computer memory. Raster scan technique is used. User input functions, user friendly software so as to function as geometrical entity. Now pause this video for a few seconds and try to write answer to the following question. Straight, true or false, primitives are three dimensional elements. Probably you have wrote answer to the following question. These are the following references. Thank you.