Consistent Visualization and Querying of GIS Databases by a Location-Aware Mobile Client Luke Benedict SE521 March 4, 2009 A Look at the 2003 Paper by Lodha, Faaland, Wong, Charaniya, Ramalingan and Keller

Agenda What are location-aware services? What are location-aware services? What is consistent visualization and what good is it? What is consistent visualization and what good is it? What are geospatial databases and how are they used? What are geospatial databases and how are they used? An example of consistent visualization An example of consistent visualization

Location-Aware Services Information provided to mobile clients Information provided to mobile clients Context-sensitive (GPS) Context-sensitive (GPS) Can be peer-to-peer and/or from central location Can be peer-to-peer and/or from central location Graphical and/or textual Graphical and/or textual

Consistent Visualization All nodes on the network see the same thing All nodes on the network see the same thing Comprised of geospatial data, aerial imagery, CAD drawings, schematics Comprised of geospatial data, aerial imagery, CAD drawings, schematics Why? Because additional, dynamic, time critical information may not be available to the mobile user Why? Because additional, dynamic, time critical information may not be available to the mobile user

Geospatial Databases Like a typical database, but has a spatial element Like a typical database, but has a spatial element Latitude, longitude, elevation, etc. Latitude, longitude, elevation, etc. Challenge: Different coordinate systems Challenge: Different coordinate systems –State Plane Coordinate System (SPCS) –Universal Transverse Mercator (UTM) –Army GRID

Querying Geospatially Spatial elements can be stored in primitives such as: Spatial elements can be stored in primitives such as: –Lines –Polygons Can be queried in ways such as: Can be queried in ways such as: –Give me all lines, polygons in a bounding box –Tell me the distance between polygon 1 and 2

Consistent Visualzation Differences in coordinate systems must be resolved Differences in coordinate systems must be resolved Clients query based on: Clients query based on: –Location (easiest) –Coordinates (usually after-the-fact) –Query (raw, give-me all…)

Example Power outage!!! Power outage!!! Electric company gets a call that a neighborhood has a power outage. Electric company gets a call that a neighborhood has a power outage.

The First Query The power company’s power grid is described in a geospatial database. The power company’s power grid is described in a geospatial database. Based on the neighborhood that is out, an analysis is done of the network using an algorithm. Based on the neighborhood that is out, an analysis is done of the network using an algorithm. It is determined that the outage is on a 50 mile transmission line. It is determined that the outage is on a 50 mile transmission line.

Clients Attack!

The Search Begins ATVs with GPS-enabled tablet PCs begin to drive the roads beneath the power line. ATVs with GPS-enabled tablet PCs begin to drive the roads beneath the power line. A helicopter overhead flys the line. A helicopter overhead flys the line. A dispatcher at company HQ guides the team. A dispatcher at company HQ guides the team.

Found It! An ATV rider finds the broken line. An ATV rider finds the broken line.

Begin Consistent Visualization The rider’s coordinates are sent back to company HQ. The rider’s coordinates are sent back to company HQ. The dispatcher sends the coordinates to the geospatial application which uses various data sources to derive a view of the situation The dispatcher sends the coordinates to the geospatial application which uses various data sources to derive a view of the situation Images, company drawings, voltage info Images, company drawings, voltage info

Example 3000 volts 1000 volts Scranton Substation # feet high G4566

Source Lodha, Faaland, Wong, Charaniya, Ramalingam and Keller (2003).Consistent Visualization and Querying of GIS Databases by a Location- Aware Mobile Agent. Proceedings of the Computer Graphics International (CGI’03), Retrieved February 13, 2009 from IEEE Xplore.