Why we need removal of hidden surface

Both realistic view and closest visible surface

for determining the closest visible surface

Both realistic view and closest visible surface

CGM QUIZ 3D CSE A

1.

The transformation in which an object can be shifted to any coordinate position in the three-dimensional plane is called
- A.
  
  Rotation
- B.
  
  Translation
- C.
  
  All of the options
- D.
  
  Scaling
Correct Answer
B. Translation

Explanation
Translation is the correct answer because it refers to the transformation in which an object is shifted to any coordinate position in the three-dimensional plane. This means that the object is moved without any rotation, scaling, or other changes in its shape or orientation. Translation involves only changing the position of the object in space, allowing it to be moved to different coordinates while maintaining its original size and shape.

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2.

The transformation in which the size of an object can be modified in x-direction ,y-direction and z-direction
- A.
  
  Translation
- B.
  
  Scaling
- C.
  
  Rotation
- D.
  
  Shear
Correct Answer
B. Scaling

Explanation
Scaling is the correct answer because it refers to the transformation that modifies the size of an object in different directions, including the x-direction, y-direction, and z-direction. Scaling can either increase or decrease the size of an object uniformly or non-uniformly, allowing for adjustments in all dimensions. This transformation is commonly used in computer graphics and image processing to resize objects or change their proportions.

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3.

If the 3-D rotation is applied to an object about x-axis, which plane will refer as plane of rotation
- A.
  
  X-Y Plane
- B.
  
  Z-X Plane
- C.
  
  Y-Z Plane
- D.
  
  None of the options
Correct Answer
C. Y-Z Plane

Explanation
When a 3-D rotation is applied to an object about the x-axis, the plane that refers to the plane of rotation is the Y-Z plane. This is because the x-axis is perpendicular to the Y-Z plane, and the rotation occurs within this plane. The X-Y plane and Z-X plane are not the planes of rotation in this case.

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4.

Apply 3-D rotation over a triangle ABC with vertices A(1,1,1), B (1,1,6), C(3,1,0) about z-axis through 90 degrees and calculate the new coordinates of the triangle ABC after rotation.
- A.
  
  A(-1,1,-1) B(-1,1,6) c(-1,3,0)
- B.
  
  A(-1,-1,1) B(-1,1,6) c(-1,3,0)
- C.
  
  A(-1,1,1) B(-1,1,6) c(-1,3,0)
- D.
  
  A(-1,1,1) B(-1,-1,6) c(-1,3,0)
Correct Answer
C. A(-1,1,1) B(-1,1,6) c(-1,3,0)

Explanation
The given question asks to apply a 3-D rotation over a triangle ABC with specific vertices. The rotation is about the z-axis through 90 degrees. After performing the rotation, the new coordinates of the triangle ABC are calculated. The correct answer is A(-1,1,1) B(-1,1,6) c(-1,3,0).

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5.

The method which is based on the principle of checking the visibility point at each pixel position on the projection plane is called
- A.
  
  Object-space method
- B.
  
  Image-space method
- C.
  
  Both Image & Space
- D.
  
  None of these
Correct Answer
B. Image-space method

Explanation
The method based on checking the visibility point at each pixel position on the projection plane is called the image-space method. This method involves determining the visibility of objects in the image by analyzing the pixel values and their positions on the projection plane. It focuses on the image itself rather than the objects in the scene or their spatial relationships.

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6.

The point, from which the observer is assumed to view the object, is called
- A.
  
  Center of projection
- B.
  
  Point of projection
- C.
  
  Point of observer
- D.
  
  View point
Correct Answer
A. Center of projection

Explanation
The correct answer is Center of projection. This is the point from which the observer is assumed to view the object. It is the point where all the lines of sight converge and determine the perspective of the object.

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7.

Orthographic projection is also known as
- A.
  
  Single view projection
- B.
  
  Two view projection
- C.
  
  Multi view projection
- D.
  
  All of the options are correct
Correct Answer
C. Multi view projection

Explanation
Orthographic projection is a type of projection used in engineering and technical drawing to represent objects in a two-dimensional form. It involves projecting the object onto a plane from multiple views, typically from the front, top, and side. This allows for a more comprehensive and accurate representation of the object, showing all its dimensions and details from different angles. Therefore, the correct answer is "Multi view projection" because it accurately reflects the nature of orthographic projection.

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8.

The orthographic projection, projection lines are ____ to each other.
- A.
  
  Parallel
- B.
  
  Perpendicular
- C.
  
  Inclined
- D.
  
  Any of the options
Correct Answer
A. Parallel

Explanation
In orthographic projection, the projection lines are parallel to each other. This means that the lines are always equidistant and never intersect or converge. This type of projection is commonly used in engineering and architecture to represent three-dimensional objects on a two-dimensional surface. By using parallel projection lines, accurate and proportional representations of objects can be achieved.

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9.

If background intensity of a scene is constant with a value 255(white) having two objects, where the first object has a point A(2,2,2) with intensity 128 and the second object has another point B(2,2,4) with intensity 100 overlap each other on 2D plane, the intensity of the location will be
- A.
  
  255
- B.
  
  128
- C.
  
  100
- D.
  
  None
Correct Answer
B. 128

Explanation
The intensity of a location in an image is determined by the intensity values of the objects that overlap at that location. In this case, the first object has a point A with intensity 128 and the second object has a point B with intensity 100. Since the two objects overlap at the location (2,2), the intensity of that location will be the intensity of the object with the higher value, which is 128. Therefore, the correct answer is 128.

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10.

Why we need removal of hidden surface
- A.
  
  for displaying realistic view
- B.
  
  For determining the closest visible surface
- C.
  
  Both realistic view and closest visible surface
- D.
  
  None of these
Correct Answer
C. Both realistic view and closest visible surface

Explanation
The removal of hidden surfaces is necessary for both displaying a realistic view and determining the closest visible surface. When rendering a scene, objects that are obstructed by other objects should not be visible in order to create a realistic view. Additionally, determining the closest visible surface is important for various applications such as collision detection or determining which object should be interacted with in a virtual environment. Therefore, both reasons contribute to the need for removing hidden surfaces.

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Cgm Quiz 3D Cse A

The transformation in which an object can be shifted to any coordinate position in the three-dimensional plane is called

The transformation in which the size of an object can be modified in x-direction ,y-direction and z-direction

If the 3-D rotation is applied to an object about x-axis, which plane will refer as plane of rotation

Apply 3-D rotation over a triangle ABC with vertices A(1,1,1), B (1,1,6), C(3,1,0) about z-axis through 90 degrees and calculate the new coordinates of the triangle ABC after rotation.

The method which is based on the principle of checking the visibility point at each pixel position on the projection plane is called

The point, from which the observer is assumed to view the object, is called

Orthographic projection is also known as

The orthographic projection, projection lines are ____ to each other.

If background intensity of a scene is constant with a value 255(white) having two objects, where the first object has a point A(2,2,2) with intensity 128 and the second object has another point B(2,2,4) with intensity 100 overlap each other on 2D plane, the intensity of the location will be

Why we need removal of hidden surface