Computer forensics

The real time computer animation resembles the moving pictures as the pictures developed with the help of these move directly on the screen. The computer games and the flight simulation are the most popular of the applications of the real time computer animation.

First take the case of computer games which can be created by the computer animation with a pictorial environment and background. Where ever the pictorial content is simple the real time animation is also easy. In this type of computer animation at least two frame buffers are used to achieve speed. They are called Page flipping or ping-ponging. Suppose there is a stationery the background and the moving object in the front. So if these have to be converted to the second frame then the moving figures are drawn again which are further redrawn into the frame buffer by copying template at the new positions.

The process of drawing the template is time consuming, if it has to be adjusted by shifting the few pixels, as parts of template could cross the boundaries. For this purpose many offset template are provided. So as soon the copying of one frame to another is completed, the display changes. These types of programs are written in assembly language due to the involvement of lot of low-level bit manipulation.

The There are certain computer games in hardware versions which work with one or more numerous sprites support. A little object whose pattern positioning is relative to a set of Cartesian coordinates is known as a sprite. The position can be controlled to a resolution of one pixel which makes it possible to keep the graphics information in RAM. This type of animated graphics reduces the software need.

The sprite can appear on the screen without being stored in the frame buffer. So when the sprite moves the background reappears automatically, it covers the screen temporarily without destroying the frame buffer. The static background picture need not to be changed as it may be the only thing stored in the frame buffer.

When a frame buffer is scanned in order to place the picture stored in this onto the CRT display the addresses of all the frame buffers for every display cycle is produced by the hardware. The hardware also produces the signals needed for the alignment of the monitor?s circuitry. These signals are used for horizontal and vertical synchronization. A CRT controller or an intelligent graphics coprocessor or sprite supporting chips are the different types of chips which send these signals and these maybe be referred to as VDP or video display processor.

This VDP has two internal registers which store the location of the screen as an(x,y) coordinate pairs of the x and y addresses of the location known as sprite x address and sprite y address respectively. Once these two addresses become equal to that of the scan line the first raster line of the sprite is included in the scan line. For doing this a sprite pointer which gives the starting address is checked by VDP for a certain location in RAM which is in generally at the end of the video memory. The working of internal counters and comparisons start when the scan line y value becomes equal to the sprite y address. And same thing happens with the x address and x value. Then the sprite starting address found when checking the RAM at the end of video memory is produced by the VDP at this point. The content of the sprite description is checked before sending it to the display circuitry. This specified sprite is uncolored as the sprite color is stored in the different register. More of the register pairs, color registers and associated checks have to be provided by the chip in order to produce many sprites.

For moving the sprites screen positions are written into the register pairs which are changed between two frames. Collision may occur when the two nontransparent bits of two or more different sprites try to be displayed at the same position and then an interrupt for the programmers use is produced by the chip. In the programmer can define priorities for the sprites due to these chips. Which, of the several sprite colors will be displayed in case the overlapping takes place are specified by these priorities. The shape of the sprite can be changed by changing its RAM area description or by using different bright descriptions by the programmer. In different display modes the sprites can have three different colors including transparent.

Then there is lookup table animation where animation can be produced by changing the values of the lookup table. When the CRT produces a frame buffer address which is to be displayed then this address is stored in the lookup table. Lookup table animation is with a popular as all desktop computers having color screens contain a demonstration portfolio of impressive pictures and many of these are animated using the same technique.

Today the aircrafts response to the movements the pilot makes using the acceleration or the direction etc, can be simulated by the help of fast computers which is referred to as flight simulation. Not only is this, but the landscape changing according to the aircraft?s movement is also possible.

The custom made graphics display processors are used for this as they can perform three dimensional transformations of data points, the filling of polygons is done rapidly in hardware due to improvement in silicon technology. Therefore, as a result the pictures composed of a number of filled polygons can be displayed with speed. Although the simulation can only be solved numerically so the fastest array processors are required. So it may be that many processors have to work simultaneously in order to create a computer animation.

This is not the last type of animation. The frame by frame animation is another which will be discussed in the third part.