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Nicholl-Lee-Nicholl Line Clipping

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Line clipping is a method of line drawing in computer graphics. It is used to remove parts of the line that are outside of the viewing area. This can be useful for making lines that are too long to fit on the screen or for removing parts of the line that are not needed.

To clip a line, first determine which part of the line is inside the viewing area and which part is outside. This can be done by comparing the x-coordinates of the endpoints of the line with the x-coordinates of the edges of the viewing area. If both endpoints have x-coordinates that are inside the viewing area, then the entire line is inside and no clipping is necessary. If both endpoints have x-coordinates that are outside the viewing area, then the entire line is outside and it will not be drawn at all. If one endpoint has an x-coordinate that is inside and one endpoint has an x-coordinate that is outside, then only part of the line will be drawn.

The next step is to find the point where the line crosses into or out of the viewing area. This can be done by finding where the y-coordinate of the line equals either the top or bottom edge of the viewing area (for a horizontal line) or where the x-coordinate equals either side edge (for a vertical line). Once this point has been found, it can be used to calculate new coordinates for one endpoint.

The Different Types of Line Clipping:

Most people are familiar with the standard line clipping algorithm, but there are actually several different types of line clipping that can be used depending on the application. The most common types are Sutherland-Hodgman, Cyrus-Beck, and Cohen-Sutherland, but there are others as well.

How Line Clipping Works:

At its most basic, line clipping works by taking a line segment and removing any part of it that lies outside of the desired clipping area. This can be done using a variety of methods, but the most common is to use a simple rectangle as the clipping area. More complex shapes can be used as well, but they require more sophisticated algorithms.

Applications for Line Clipping:

Line clipping is commonly used in computer graphics and CAD applications to produce clean lines and shapes within a given space. It can also be used for more practical purposes such as hiding parts of an image that would otherwise be visible outside the intended viewing area.

Applications:

There are many applications for the Nicholl-Lee-Nicholl line clipping algorithm. For example, it can be used to find the intersection of two lines, to compute the shortest distance between two lines, or to find the point on a line closest to a given point. Additionally, the algorithm can be used to clip a line segment against a convex polygon.

Advantages:

There are several advantages to Nicholl-Lee-Nicholl line clipping. First, it is a simple and efficient algorithm that can be easily implemented. Second, it guarantees that the clipped line will be visible in the final image. Third, it does not introduce any artifacts into the final image. Finally, it is a fast and robust algorithm that can handle a wide variety of input line segments.

Disadvantages:

There are several disadvantages of the Nicholl-Lee-Nicholl line clipping algorithm. Firstly, it is not guaranteed to find the optimal solution. Secondly, it can be computationally expensive, particularly in cases where there are a large number of vertices and edges. Finally, the algorithm can produce unpredictable results if the input data is not properly formatted.

Real-Time Uses:

  1. In computer graphics, the Nicholl–Lee–Nicholl (N-L-N) algorithm is a clipping algorithm used to remove parts of lines that lie outside a user-specified window.
  2. The N-L-N algorithm is one of many algorithms that can be used to clip lines. It is a simple algorithm that can be implemented easily and efficiently.
  3. The N-L-N algorithm works by dividing the line into two parts: the part inside the window (the visible part) and the part outside the window (the invisible part).
  4. The visible part of the line is then drawn, and the invisible part is discarded.
  5. The N-L-N algorithm is not perfect, however. It can produce “staircase” artifacts when lines are not perfectly horizontal or vertical. However, these artifacts can be minimized by using a different clipping algorithm, such as the Cohen–Sutherland algorithm.
Cohen–Sutherland Algorithm

 

Cohen-Sutherland line clipping sometimes does multiple calculations to find intersection points for a given line segment.

  1. NLN line clipping procedure avoids any issues with intersection calculation.
  2. The added regions in NLN help to avoid multiple clipping of individual line segments.
  3. NLN line clipping, tends to be more efficient than RNN line clipping because it does fewer comparisons, divisions, etc.
  4. The NLN line clipping algorithm cannot be extended to three-dimensional MRI data.
  5. If the point falls into one of the three regions, we transfer it to one of them by using transformations.
  6. Furthermore, we can apply this method to all nine regions.

Last Updated : 13 Nov, 2022
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