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Sneha B N
Clustering
Methods
Clustering
 Clustering = Unsupervised learning
technique
 Groups data points into clusters based
on similarity
Popular Clustering Methods:
 K-Means Clustering
 Hierarchical Clustering
 DBSCAN (Density-Based Spatial
Clustering of Applications with Noise)
K-Means Clustering:
 Divides data into k clusters
 Assumes spherical clusters
 Sensitive to outliers
 Needs to predefine k
Hierarchical Clustering:
 Builds a hierarchy of clusters (tree-like
structure)
 Agglomerative (bottom-up) or Divisive (top-
down)
 Good for small datasets
 Computationally expensive for large data
What is DBSCAN?
 Density-Based Spatial Clustering of Applications with Noise
 Groups together points that are closely packed (high
density)
 Separates low-density regions (noise/outliers)
Key Concepts in DBSCAN
 Epsilon (ε): Radius to search for neighbors
 MinPts: Minimum number of points to form a dense
region
 Points classified as:
 Core Points (dense enough)
 Border Points (less dense, but close)
 Noise Points (outliers)
Why DBSCAN?
 Real-world data isn't always spherical or
even!
 Clusters of arbitrary shape can exist
 No need to predefine number of
clusters (unlike k-means)
 Can detect outliers (noise)
DBSCAN Advantages
 Can find clusters of arbitrary shape
 No need to specify number of
clusters
 Robust to outliers
 Works well with spatial data
 Efficient for Large Datasets
DBSCAN Disadvantages
 Hard to choose good ε and MinPts
 Struggles with clusters of varying
densities
 Performance drops on high-
dimensional data
DBSCAN in Space Robotics
and Terrain Mapping
 🚀 Used in NASA/ESA space missions for 3D mapping using
LiDAR or stereo vision.
 🧠 Clusters 3D point cloud data to identify terrain features:
Rocks, cliffs, craters (non-spherical shapes).
 🤖 Supports autonomous navigation of rovers by segmenting
obstacles and traversable paths.
 🌌 Ideal for unstructured, noisy environments like Mars or the
Moon.
Research on DBSCAN with
Point Cloud Data
 📚 Efficient Clustering of LiDAR Data for 3D Object Detection -
IEEE Paper using DBSCAN for 3D object detection from LiDAR
data.
 📚 DBSCAN in SLAM (Simultaneous Localization and Mapping) -
Improves mapping precision by filtering noise in point clouds.
 🌕 Lunar/Martian Terrain Segmentation - DBSCAN helps classify
terrain types and supports hazard detection and mission
planning.

Clustering_Methods_Updated presentation..

  • 1.
  • 2.
    Clustering  Clustering =Unsupervised learning technique  Groups data points into clusters based on similarity Popular Clustering Methods:  K-Means Clustering  Hierarchical Clustering  DBSCAN (Density-Based Spatial Clustering of Applications with Noise)
  • 3.
    K-Means Clustering:  Dividesdata into k clusters  Assumes spherical clusters  Sensitive to outliers  Needs to predefine k
  • 4.
    Hierarchical Clustering:  Buildsa hierarchy of clusters (tree-like structure)  Agglomerative (bottom-up) or Divisive (top- down)  Good for small datasets  Computationally expensive for large data
  • 5.
    What is DBSCAN? Density-Based Spatial Clustering of Applications with Noise  Groups together points that are closely packed (high density)  Separates low-density regions (noise/outliers) Key Concepts in DBSCAN  Epsilon (ε): Radius to search for neighbors  MinPts: Minimum number of points to form a dense region  Points classified as:  Core Points (dense enough)  Border Points (less dense, but close)  Noise Points (outliers)
  • 8.
    Why DBSCAN?  Real-worlddata isn't always spherical or even!  Clusters of arbitrary shape can exist  No need to predefine number of clusters (unlike k-means)  Can detect outliers (noise)
  • 9.
    DBSCAN Advantages  Canfind clusters of arbitrary shape  No need to specify number of clusters  Robust to outliers  Works well with spatial data  Efficient for Large Datasets
  • 10.
    DBSCAN Disadvantages  Hardto choose good ε and MinPts  Struggles with clusters of varying densities  Performance drops on high- dimensional data
  • 11.
    DBSCAN in SpaceRobotics and Terrain Mapping  🚀 Used in NASA/ESA space missions for 3D mapping using LiDAR or stereo vision.  🧠 Clusters 3D point cloud data to identify terrain features: Rocks, cliffs, craters (non-spherical shapes).  🤖 Supports autonomous navigation of rovers by segmenting obstacles and traversable paths.  🌌 Ideal for unstructured, noisy environments like Mars or the Moon.
  • 12.
    Research on DBSCANwith Point Cloud Data  📚 Efficient Clustering of LiDAR Data for 3D Object Detection - IEEE Paper using DBSCAN for 3D object detection from LiDAR data.  📚 DBSCAN in SLAM (Simultaneous Localization and Mapping) - Improves mapping precision by filtering noise in point clouds.  🌕 Lunar/Martian Terrain Segmentation - DBSCAN helps classify terrain types and supports hazard detection and mission planning.