3D Computer Vision: Reconstructing and Analyzing 3D Scenes

Question 1

Which technique is commonly used to create 3D models from multiple images?

Accepted Answer

Structure from Motion (SfM)

Answer

Homography estimation

Answer

Ray tracing

Answer

Principal component analysis (PCA)

Question 2

Which topic is typically not covered in 3D Computer Vision units?

Accepted Answer

Natural Language Processing

Answer

3D Scene Reconstruction

Answer

Multiple View Geometry

Question 3

Which of the following data structures is commonly used to represent collections of 3D points?

Accepted Answer

Octree

Answer

LinkedList

Answer

Hash table

Answer

Queue

Question 4

What is the primary role of epipolar geometry in the context of 3D Computer Vision?

Accepted Answer

Establishing correspondences between points in multiple images.

Answer

Estimating camera parameters

Answer

Generating 3D models

Answer

Object recognition

Question 5

Which camera model is widely used in the field of 3D Computer Vision?

Accepted Answer

Pinhole camera model

Answer

Fisheye camera model

Answer

Cylindrical camera model

Answer

Spherical camera model

Question 6

Which of these methods is NOT typically employed for 3D reconstruction using multiple images?

Accepted Answer

Convolutional Neural Networks (CNNs)

Answer

Stereo Vision

Answer

Multi-View Stereo (MVS)

Answer

Structure from Motion (SfM)

Question 7

What is the primary function of a depth map in 3D computer vision?

Accepted Answer

To represent the distance of each pixel from the camera.

Answer

To detect edges and corners.

Answer

To enhance image contrast.

Question 8

What presents a significant challenge in 3D object recognition compared to its 2D counterpart?

Accepted Answer

Handling variations in object pose and viewpoint.

Answer

Classifying objects based on color.

Answer

Dealing with image noise.

Answer

Recognizing textures and patterns.

Question 9

Which of the following is NOT a typical application of 3D computer vision?

Accepted Answer

Text recognition in images.

Answer

3D modeling and animation.

Answer

Autonomous driving.

Answer

Virtual reality and augmented reality.

Question 10

What is the main purpose of camera calibration in 3D computer vision?

Accepted Answer

To determine the camera's intrinsic and extrinsic parameters.

Answer

To remove noise from images.

Answer

To enhance image quality.

Question 11

In the context of 3D reconstruction, what does epipolar geometry define?

Accepted Answer

The geometric relationship between two images captured from different viewpoints.

Answer

Features of interest within images.

Answer

3D object recognition.

Question 12

What is a fundamental matrix in 3D computer vision?

Accepted Answer

A 3x3 matrix that relates corresponding points in two images.

Answer

A matrix used for image segmentation.

Answer

A matrix representing the camera's intrinsic parameters.

Question 13

Which technique is commonly employed for 3D object tracking?

Accepted Answer

Kalman filtering.

Answer

Canny edge detection.

Answer

SIFT feature extraction.

Answer

Principal Component Analysis (PCA).

Question 14

What is the main difference between a voxel grid and a point cloud?

Accepted Answer

A voxel grid represents space as a regular grid of 3D cells, while a point cloud is an unorganized set of points.

Answer

A voxel grid is more efficient for storing data.

Question 15

Which of the following is NOT a common approach for 3D reconstruction?

Accepted Answer

Image segmentation

Answer

Structure from motion

Answer

Shape from shading

Answer

Stereo correspondence

Question 16

**Precisely define the primary objective of camera calibration in the context of 3D computer vision.**

Accepted Answer

Precisely estimating both the **intrinsic and extrinsic** parameters of a particular camera.

Answer

Primarily improving the overall quality of the image.

Answer

Correcting for lens distortions encountered.

Question 17

**When employing depth sensors for 3D reconstruction, which of the following stands out as a significant advantage?**

Accepted Answer

Obtaining depth measurements **directly**.

Answer

Capturing a wide field of view.

Answer

Cost-effectiveness in terms of computation.

Answer

Exceptionally high levels of accuracy.

Question 18

**Succinctly describe the primary function of point cloud registration.**

Accepted Answer

Aligning multiple point clouds within a **common coordinate system**.

Answer

Generating a mesh from a given point cloud.

Answer

Removing unwanted noise and outliers from the point cloud.

Question 19

**In the realm of 3D computer vision, what stands out as a primary challenge in recognizing objects?**

Accepted Answer

Dealing with **occlusions and clutter**.

Answer

Blurring caused by motion.

Answer

Variations in lighting conditions.

Answer

Images with insufficient resolution.

Question 20

**In the context of 3D computer vision, what crucial role does deep learning play?**

Accepted Answer

Extracting high-level features and making predictions.

Answer

Enhancing the accuracy of 3D reconstruction.

Answer

Replacing traditional computer vision algorithms entirely.

Question 21

**When exploring the potential applications of 3D computer vision in healthcare, which of the following stands out as a promising area?**

Accepted Answer

Surgical planning & precise navigation during procedures.

Answer

Image enhancement for improved visualization.

Answer

Analysis of medical images for diagnostic purposes.

Answer

Data visualization for effective communication.

Question 22

**When comparing dense and sparse point clouds, what's the key difference to keep in mind?**

Accepted Answer

Dense point clouds feature a **higher density of points** per unit area.

Answer

Sparse point clouds are exclusively generated from depth images.

Answer

Dense point clouds are inherently more accurate.

Question 23

**In the context of 3D computer vision, which file format is commonly used for storing 3D point clouds?**

Accepted Answer

**PLY** (Polygon File Format).

Answer

XML (Extensible Markup Language).

Answer

TXT (Plain Text).

Answer

JPEG (Joint Photographic Experts Group).

Question 24

**In 3D computer vision, what's the significance of utilizing ground truth data?**

Accepted Answer

Evaluating the **accuracy of reconstruction algorithms**.

Answer

Training machine learning models for various tasks.

Answer

Generating synthetic data for training and testing.

Question 25

**When it comes to 3D reconstruction from multiple images, which of the following is NOT a commonly used approach?**

Accepted Answer

**Direct Linear Transformation (DLT)**.

Answer

Stereo Vision.

Answer

Multi-View Stereo (MVS).

Answer

Structure from Motion (SfM).

Question 26

What is the main purpose of feature matching in 3D Computer Vision?

Accepted Answer

Identifying corresponding points in different images to establish geometric relationships.

Answer

Segmenting objects in a scene.

Answer

Classifying objects based on their appearance.

Question 27

Which of these algorithms is commonly used for dense 3D reconstruction?

Accepted Answer

Multi-View Stereo (MVS)

Answer

K-means Clustering

Answer

SIFT (Scale-Invariant Feature Transform)

Answer

RANSAC (RANdom SAmple Consensus)

Question 28

What is the primary challenge associated with using stereo vision for 3D reconstruction?

Accepted Answer

Determining the disparity between corresponding points in the left and right images.

Answer

Segmenting objects from the background.

Answer

Handling varying lighting conditions.

Question 29

In Structure from Motion (SfM), what is the primary goal of bundle adjustment?

Accepted Answer

Optimizing camera poses and 3D point locations simultaneously.

Answer

Detecting and removing outliers in the scene.

Answer

Calibrating the camera's intrinsic parameters.

Question 30

What is the role of a depth map in 3D Computer Vision?

Accepted Answer

Representing the distance of each pixel in a scene from the camera.

Answer

Classifying objects based on their shape.

Answer

Segmenting objects from the background.

Question 31

Which of these is a common application of 3D Computer Vision in robotics?

Accepted Answer

Navigation and obstacle avoidance.

Answer

Medical image analysis.

Answer

Face recognition.

Answer

Image compression.

Question 32

What is the fundamental difference between a point cloud and a mesh?

Accepted Answer

A point cloud represents a set of 3D points, while a mesh is a connected set of points forming a surface.

Answer

A point cloud is used for 2D, while a mesh is used for 3D.

Question 33

Which of the following is NOT a factor affecting the accuracy of 3D reconstruction?

Accepted Answer

The size of the camera sensor.

Answer

The quality of the camera calibration.

Answer

The number of images used.

Answer

The presence of noise and occlusion in the scene.

Question 34

What is the role of a depth sensor in 3D Computer Vision?

Accepted Answer

Directly measuring the distance between the sensor and objects in the scene.

Answer

Detecting edges and corners in images.

Answer

Recognizing objects based on their shape.

Question 35

Which technique is commonly used to estimate depth information from a pair of stereo images?

Accepted Answer

Epipolar geometry

Answer

Histogram of Oriented Gradients

Answer

Convolutional Neural Networks

Question 36

What is the role of a point cloud in 3D computer vision?

Accepted Answer

Represents the surface of an object or scene as a set of 3D points

Answer

Segments an image into different regions based on color

Answer

Detects edges and corners in an image

Question 37

Which of the following is NOT a common application of Structure from Motion (SfM)?

Accepted Answer

Object detection in real-time video streams

Answer

Reconstructing accident scenes for forensic analysis

Answer

3D modeling of historical sites

Answer

Creating virtual tours of cities

Question 38

What is the purpose of the Iterative Closest Point (ICP) algorithm?

Accepted Answer

To align two point clouds by minimizing the distance between corresponding points

Answer

To extract features from a point cloud for object recognition

Answer

To segment a point cloud into different objects

Question 39

What type of camera is often used in Time-of-Flight (ToF) cameras for depth sensing?

Accepted Answer

Infrared

Answer

Thermal

Answer

Monochrome

Answer

RGB

Question 40

Which method utilizes structured light patterns projected onto a scene for 3D reconstruction?

Accepted Answer

Structured light scanning

Answer

Passive stereo vision

Answer

Shape from shading

Answer

Photometric stereo

Question 41

What is a key advantage of using a voxel representation over a point cloud for 3D data?

Accepted Answer

Allows for efficient representation of volumetric information

Answer

Simplifies the process of feature extraction

Answer

Reduces memory requirements for storing 3D data

Question 42

What information can be extracted from the epipolar geometry between two views of a scene?

Accepted Answer

Relative camera pose and 3D point correspondences

Answer

Object classification and scene understanding

Answer

Optical flow and motion estimation

Answer

Image segmentation and boundary detection

Question 43

What is the goal of SLAM (Simultaneous Localization and Mapping) algorithms in robotics?

Accepted Answer

Build a map of the environment while simultaneously estimating the robot's pose

Answer

Control the movement of a robot arm with high precision

Answer

Recognize and classify objects in a cluttered environment

Question 44

Which of the following is a deep learning architecture specifically designed for 3D point cloud processing?

Accepted Answer

PointNet

Answer

YOLO

Answer

ResNet

Answer

AlexNet

Question 45

Which of the following methods is NOT a common approach to 3D reconstruction from multiple images?

Accepted Answer

Neural Network-based Object Recognition

Answer

Multi-View Stereo (MVS)

Answer

Stereo Vision

Answer

Structure from Motion (SfM)

Question 46

What is the primary advantage of using a depth camera for 3D scene capture compared to traditional cameras?

Accepted Answer

Direct measurement of depth information

Answer

Wider field of view

Answer

Higher resolution images

Answer

Ability to capture moving objects

Question 47

In a stereo vision system, what is the role of the baseline?

Accepted Answer

The distance between the two cameras

Answer

The type of sensor used in the cameras

Answer

The resolution of the cameras

Answer

The focal length of the cameras

Question 48

Which of the following is NOT a common application of 3D Computer Vision?

Accepted Answer

Image compression

Answer

Autonomous navigation

Answer

Virtual reality and augmented reality

Answer

3D modeling and animation

Question 49

What is the main challenge in performing 3D reconstruction from images captured under varying lighting conditions?

Accepted Answer

Maintaining consistency in feature detection and matching across different lighting

Answer

The need for more powerful cameras

Answer

The increased computational complexity

Question 50

How does the process of point cloud registration contribute to 3D reconstruction?

Accepted Answer

Aligning and merging multiple point clouds to create a complete 3D model

Answer

Identifying specific objects within the 3D scene

Answer

Reducing noise in the captured point cloud data

Question 51

What is the main difference between a voxel grid and a point cloud for representing 3D data?

Accepted Answer

Voxel grids represent 3D space as a regular grid of volume elements, while point clouds are sets of discrete 3D points

Answer

Voxel grids are more accurate, while point clouds are more efficient

Question 52

Which of the following techniques is commonly used for 3D object recognition in cluttered scenes?

Accepted Answer

3D Keypoint Descriptors

Answer

Edge detection algorithms

Answer

Texture analysis

Answer

Color histograms

Question 53

What is the role of a depth map in the process of 3D reconstruction?

Accepted Answer

Providing depth information for each pixel in an image, allowing for 3D point cloud generation

Answer

Segmenting the image into different regions

Answer

Identifying the edges and contours of objects in the scene

Question 54

Which of the following is a key advantage of using a structured light approach for 3D scanning compared to other methods?

Accepted Answer

Higher accuracy and resolution in depth measurement

Answer

Ability to capture moving objects

Answer

Lower computational cost