125 research outputs found
An Efficient Approach to Clustering in Large Multimedia Databases with Noise".
Abstract Several clustering algorithms can be applied to clustering in large multimedia databases. The effectiveness and efficiency of the existing algorithms, however, is somewhat limited, since clustering in multimedia databases requires clustering high-dimensional feature vectors and since multimedia databases often contain large amounts of noise. In this paper, we therefore introduce a new algorithm to clustering in large multimedia databases called DENCLUE (DENsitybased CLUstEring). The basic idea of our new approach is to model the overall point density analytically as the sum of influence functions of the data points. Clusters can then be identified by determining density-attractors and clusters of arbitrary shape can be easily described by a simple equation based on the overall density function. The advantages of our new approach are (1) it has a firm mathematical basis, (2) it has good clustering properties in data sets with large amounts of noise, (3) it allows a compact mathematical description of arbitrarily shaped clusters in high-dimensional data sets and (4) it is significantly faster than existing algorithms. To demonstrate the effectiveness and efficiency of DENCLUE, we perform a series of experiments on a number of different data sets from CAD and molecular biology. A comparison with DBSCAN shows the superiority of our new approach
Detecting Stops from GPS Trajectories: A Comparison of Different GPS Indicators for Raster Sampling Methods
With the increasing prevalence of GPS tracking capabilities on smartphones, GPS
trajectories have proven to be useful for an extensive range of research topics. Stop
detection, which estimates activity locations, is fundamental for organizing GPS
trajectories into semantically meaningful journeys. With previous methods
overwhelmingly dependent on thresholds, contextual information or a pre-understanding
of the GPS records, this paper addresses the challenge by contributing a ‘top-down’ raster
sampling method which samples pre-calculated GPS indicators and clusters the raster cells
with significantly different values as stops. We report a comparison of a set of precalculated
GPS indicators with two baseline methods. By referencing a ground truth travel
dairy, the raster sampling method demonstrates good and reliable capabilities on producing
high accuracy, low redundancy and close proximity to the ground truth in three distinct
travel use cases. This further indicates a good generic stop detection method
ADBSCAN: Adaptive Density-Based Spatial Clustering of Applications with Noise for Identifying Clusters with Varying Densities
Density-based spatial clustering of applications with noise (DBSCAN) is a
data clustering algorithm which has the high-performance rate for dataset where
clusters have the constant density of data points. One of the significant
attributes of this algorithm is noise cancellation. However, DBSCAN
demonstrates reduced performances for clusters with different densities.
Therefore, in this paper, an adaptive DBSCAN is proposed which can work
significantly well for identifying clusters with varying densities.Comment: To be published in the 4th IEEE International Conference on
Electrical Engineering and Information & Communication Technology (iCEEiCT
2018
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