Consistent Visualization Consistent Visualization and Querying of GIS and Querying of GIS

Databases by a Location-Databases by a Location-Aware Mobile ClientAware Mobile Client

Luke BenedictLuke Benedict

SE521SE521

March 4, 2009March 4, 2009

A Look at the 2003 Paper by Lodha, Faaland, Wong, Charaniya, Ramalingan and Keller

AgendaAgenda

• What are location-aware services?What are location-aware services?

• What is consistent visualization and What is consistent visualization and what good is it?what good is it?

• What are geospatial databases and What are geospatial databases and how are they used?how are they used?

• An example of consistent An example of consistent visualizationvisualization

Location-Aware ServicesLocation-Aware Services

• Information provided to mobile Information provided to mobile clientsclients

• Context-sensitive (GPS)Context-sensitive (GPS)

• Can be peer-to-peer and/or from Can be peer-to-peer and/or from central locationcentral location

• Graphical and/or textualGraphical and/or textual

Consistent VisualizationConsistent Visualization

• All nodes on the network see the All nodes on the network see the same thingsame thing

• Comprised of geospatial data, aerial Comprised of geospatial data, aerial imagery, CAD drawings, schematicsimagery, CAD drawings, schematics

• Why? Because additional, dynamic, Why? Because additional, dynamic, time critical information may not be time critical information may not be available to the mobile useravailable to the mobile user

Geospatial DatabasesGeospatial Databases

• Like a typical database, but has a Like a typical database, but has a spatial elementspatial element

• Latitude, longitude, elevation, etc.Latitude, longitude, elevation, etc.

• Challenge: Different coordinate Challenge: Different coordinate systemssystems– State Plane Coordinate System (SPCS)State Plane Coordinate System (SPCS)– Universal Transverse Mercator (UTM)Universal Transverse Mercator (UTM)– Army GRIDArmy GRID

Querying GeospatiallyQuerying Geospatially

• Spatial elements can be stored in Spatial elements can be stored in primitives such as:primitives such as:– LinesLines– PolygonsPolygons

• Can be queried in ways such as:Can be queried in ways such as:– Give me all lines, polygons in a bounding Give me all lines, polygons in a bounding

boxbox– Tell me the distance between polygon 1 and Tell me the distance between polygon 1 and

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Consistent VisualzationConsistent Visualzation

• Differences in coordinate systems Differences in coordinate systems must be resolvedmust be resolved

• Clients query based on:Clients query based on:– Location (easiest)Location (easiest)– Coordinates (usually after-the-fact)Coordinates (usually after-the-fact)– Query (raw, give-me all…)Query (raw, give-me all…)

ExampleExample

• Power outage!!!Power outage!!!

• Electric company gets a call that a Electric company gets a call that a neighborhood has a power outage.neighborhood has a power outage.

The First QueryThe First Query

• The power company’s power grid is The power company’s power grid is described in a geospatial database. described in a geospatial database.

• Based on the neighborhood that is Based on the neighborhood that is out, an analysis is done of the out, an analysis is done of the network using an algorithm.network using an algorithm.

• It is determined that the outage is on It is determined that the outage is on a 50 mile transmission line.a 50 mile transmission line.

Clients Attack!Clients Attack!

The Search BeginsThe Search Begins

• ATVs with GPS-enabled tablet PCs ATVs with GPS-enabled tablet PCs begin to drive the roads beneath the begin to drive the roads beneath the power line.power line.

• A helicopter overhead flys the line.A helicopter overhead flys the line.

• A dispatcher at company HQ guides A dispatcher at company HQ guides the team.the team.

Found It!Found It!

• An ATV rider finds the broken line.An ATV rider finds the broken line.

Begin Consistent Begin Consistent VisualizationVisualization

• The rider’s coordinates are sent back The rider’s coordinates are sent back to company HQ.to company HQ.

• The dispatcher sends the coordinates The dispatcher sends the coordinates to the geospatial application which to the geospatial application which uses various data sources to derive a uses various data sources to derive a view of the situationview of the situation

• Images, company drawings, voltage Images, company drawings, voltage infoinfo

ExampleExample

3000 volts

1000 volts

Scranton Substation #2132

250 feet high

G4566

SourceSource

Lodha, Faaland, Wong, Charaniya, Ramalingam and Lodha, Faaland, Wong, Charaniya, Ramalingam and Keller (2003).Consistent Visualization and Keller (2003).Consistent Visualization and Querying of GIS Databases by a Location- Aware Querying of GIS Databases by a Location- Aware Mobile Agent. Proceedings of the Computer Mobile Agent. Proceedings of the Computer Graphics International (CGI’03), 248-253. Graphics International (CGI’03), 248-253. Retrieved February 13, 2009 from IEEE Xplore. Retrieved February 13, 2009 from IEEE Xplore.