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## Which is true for back-face detection algorithm Mcq?

Which is true for back-face detection? Which of these is a visible surface detection algorithm? In the depth buffer method which buffer is/are used? Which surface algorithm is based on perspective depth?…

(a) Depth comparison
(b) Z-buffer or depth-buffer algorithm
(c) Subdivision method
(d) Back-face removal

What is the importance of visible surface detection in computer graphics?

Abstract— In computer graphics, there are many surface detection algorithms. When we view a picture containing non-transparent objects and surfaces, then we cannot see those objects from view which is behind from objects closer to eye. We must remove these hidden surfaces to get a realistic screen image.

### What are the two approaches of visible surface detection in computer graphics?

There are two approaches for removing hidden surface problems − Object-Space method and Image-space method. The Object-space method is implemented in physical coordinate system and image-space method is implemented in screen coordinate system.

What is the classification of visible surface detection algorithm?

There are two types of visible surface detection algorithm 1) object space method and 2)image space method.

## Which is the true for back face detection?

The Back-face detection method is very simple. For the left-handed system, if the Z component of the normal vector is positive, then it is a back face. Thus, for the right-handed system, if the Z component of the normal vector is negative, then it is a back face.

How many types of hidden surface algorithms are there?

We have discussed five different hidden surface algorithms: z-buffer, scan line, ray casting, depth sort, and bsp-tree. Two key ideas are applied to help increase the speed of these algorithms: sorting of edges by depth, and pixel coherence for depth and intensity.

### Which algorithm is used to calculate visibility?

An angular sweep, i.e. rotational plane sweep algorithm to compute the visibility polygon was proposed in 1985 and 1986. The idea is to first sort all the segment endpoints by polar angle, and then iterate over them in that order. During the iteration, the event line is maintained as a heap.

What is image space algorithm?

Image-Space method:- Image space method is implemented in the screen coordinate system in which the objects are viewed. In an image-space algorithm, visibility is decided point by point at each pixel Position on the view plane.

## How many types of hidden surface algorithm are there?

five different hidden
We have discussed five different hidden surface algorithms: z-buffer, scan line, ray casting, depth sort, and bsp-tree. Two key ideas are applied to help increase the speed of these algorithms: sorting of edges by depth, and pixel coherence for depth and intensity.

What does back face mean?

backface (plural backfaces) (computer graphics) The back side of a face of a mesh, which typically will never face the camera and can thus be culled (discarded) from the list of items to be rendered.

### Which algorithm is used for hidden-line removal?

Parallel algorithms Hidden-surface algorithms can be used for hidden-line removal, but not the other way around. Reif and Sen proposed an O(log4 n)-time algorithm for the hidden-surface problem, using O((n + v)/log n) CREW PRAM processors for a restricted model of polyhedral terrains, where v is the output size.

What are the types of hidden surface removal algorithm?

Algorithms used for hidden line surface detection

• Back Face Removal Algorithm.
• Z-Buffer Algorithm.
• Painter Algorithm.
• Scan Line Algorithm.
• Subdivision Algorithm.
• Floating horizon Algorithm.

## How is back-face detection used in computer graphics?

Back-Face Detection ● Back-face detection can identify all the hidden surfaces in a scene that contain non- overlapping convex polyhedra. ● But we have to apply more tests that contain overlapping objects along the line of sight to determine which objects obscure which objects. 10.

How to detect the back face of a polygon?

6. Back-Face Detection ● Back-face detection of 3D polygon surface is easy ● Recall the polygon surface equation: ● We need to also consider the viewing direction when determining whether a surface is back-face or front-face. ● The normal of the surface is given by: 0<+++ DCzByAx ),, ( CBA=N 7.

### Which is the best back face detection method?

Back-Face detection, also known as Plane Equation method, is an object space method in which objects and parts of objects are compared to find out the visible surfaces. Let us consider a triangular surface that whose visibility needs to decided. The idea is to check if the triangle will be facing away from…

How to find the back face of an object?

1) Compute N for every face of object. The Back-face detection method is very simple. For the left-handed system, if the Z component of the normal vector is positive, then it is a back face. If the Z component of the vector is negative, then it is a front face.