Before displaying the 3-D picture one more set of “viewing transformations” is to be done. This is to ensure that the viewer would get the depth perspective that has been displayed on the screen. This is done by transforming the image to another coordinate system with axes xe, ye and ze, the origin being the … Read more
Rotation in 3-dimensions is a more complex affair. (In fact, even in 2 dimensions, rotation was more involved than scaling or translation because the concept of point of rotation). This is because; the rotation takes place about an axis. The same point, given the same amount of rotation, gets transformed to different points depending on … Read more
Just as in the case of 2D, we represent the transformation operations as a series of matrix operations. With this, we obtain the flexibility of sequencing a series of operations one after the other to get the desired results on one hand and also the ability to undo the operations, by resorting to the reverse … Read more
A variable yprev is used to keep track of the previous intersection of the edge. Whenever an intersection is found, not only is a new pair of (x,y) stored as in the yx algorithm, but the y coordinate is stored to indicate the previous intersection by storing it in yprev. Initially its value is set … Read more
For every edge of the polygon, find out it’s intersection with all the scan lines (This is a fairly straight forward process, because beginning with one tip of the edge, every incremental value of y gives the next scan line and hence a DDA type algorithm can be written to compute all such intersections very … Read more
The performance of a scan conversion algorithm can be substantially improved by taking advantage of the property of coherence i.e. Given a pixel that is inside a polygon, it’s immediately adjacent pixels are most likely to be also inside the polygon. Similarity if a pixel is outside a polygon, most of its adjacent ones also … Read more
The simplest algorithm of scan conversion can do something like this Display the boundary of the solid object For each pixel on the screen, try to find out whether it lies inside the boundary or on the boundary or outside it. Suitably arrange the mask of each. Though this method is simple and reliable, it … Read more
The main reason for the rapid increase in popularity of raster scan displays is their ability to display “solid” images. They are useful in representative, thickness, depth, or objects line up one behind another. Needless to say, the ability to display the third dimension is of prime importance in realistic display of objects, especially in … Read more
It is common experience that while in motion; objects that are far away appear to move much slower than those near by. The same can be used in the reverse method to give an indication of depth, especially in motion pictures. The objects that are supposed to be nearer to the viewer can be made … Read more