Beijing University
of Posts
VAST 2008 Challenge
Mini Challenge 2: Migrant Boats (geo-temporal analysis)
Authors and
Affiliations:
Qi Ye,
Deyong hu,
Student team: YES
faculty advisor:
Bin Wu,
Bai Wang,
Tool(s):
In order to combine the
analysis of geographic information and link relationships, we developed a tool
called GeoTemporalNet based on the framework called
JSNVA. GeoTemporalNet is composed of two major parts, one part is used to show the
geographical information in the grid on the panel and the other part is used to
show the structure of different networks. JSNVA (Java Straight-line
drawing Network Visual Analysis framework) is a software framework JSNVA for
network visual analysis in different applications. JSNVA has a clear
architecture and supports a more systematic way of implementing different
straight-line graph drawing algorithms which show different networks on
different views. JSNVA can be used as a front-end for visualization and a
back-end for analysis in applications, and it can be customized for different
applications. The paper of more details about JSNVA will be published in
ADMA2008. Based on JSNVA, the data in GeoTemporalNet’s applications are stored in a
graph structure as nodes and edges, and if there are relations between two
nodes there will be an edge. The information in nodes and edges can be stored
and achieved by different keys, such as time, position, names et al.
In this mini
challenge, we just use the node data structure to record the positions of
different boats. Both of the time
information and position information of each boat is stored in these nodes. By using this tool users can not only get the temporal information of all boats’ positions dynamically.
Boat-1 Characterize the choice of landing sites and their evolution over
the three years.
Detailed Answer:
In the first year, from January 2005 to December 2005, most landing
sites were clustered in the area from -81 x 25.5 to -80 x 24.2, as shown in figure 1 (A). During the 3 years most of vessels in this data set were also in this area. In the second year, from January 2006 to December 2006,
there were many vessels began to land on the west coast. The coordinate of landing sites
was much wider which is mainly from -83 x 27.7 to -80 x 22.4, as shown in figure 1 (B). In April 2006, there were some vessels started to land in the
area
near -86.7 x 21.2, and all the vessels landed successfully in this area during three years. In the last year, from January
2007 to December 2007, there were many vessels
landed on the east coast. The landing
sites were even wider which was
mainly from -83 x 29.5 to -79.5 x 22.3. There was also a small area for landing whose coordinate was about -86.7 x 21.2. All the boats went there landing successfully. As this area was very small and dense, we thought this area must be an island. We can see the landing
sites over time by this video.
The red nodes indicate the boats which landed successfully and the cyan nodes indicate the boats which were intercepted. In figure 1, the size of nodes indicates different types of boats.
Figure 1 encountering
coordinates of migrant boats each year (A) 2005 (B) 2006 (C) 2007
Boat-2 Characterize the geographical patterns of interdiction over the three years
Short Answer:
The center of Isla Del Sueńo
island’s position is about -79.95 x 23.75. As shown
in figure 1, during these 3 years, the positions
where migrant boats were intercepted got much closer to the island. As the
landing area became much wider, the positions where these migrant were intercepted
also became much wider. However, we can still find that there are two areas that migrant boats seldom been intercepted; one area was from the coordinate of -81 x 29.9 to -80 x 22.6. The other area’s coordinate was about -86.7 x 21.2. The migrants who went there had never been intercepted.
Boat- 3 What is the successful landing rate over the time period?
Short Answer:
Figure 2 successful landing rate over the three years
In 2005 the successful landing rate kept on growing from beginning
and in October it reached the peak value of that year which was 0.667. After it reached the peak value, the successful
landing rate dropped quickly. In
February 2006, the successful landing rate was 0. After that it grew quickly, in September 2006 it reached the peak whose rate was 0.70. In the rest of the time period the successful landing rates kept at high values most of which were above 0.5. In March 2007 it reached the peak in 2007, and the rate was about 0.69.