Transcript Dynamic Map Service Integration

Dynamic Map Service
Integration
Business Case for Implementation
Craig Wolff, M.S. Eng
CA Environmental Health Tracking Program
Environmental Health Investigations Branch
CA Department of Health Services
Impact Assessment, Inc.
[email protected] http://ehib.org http://catracking.com
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CA Environmental Health Tracking
Program (CEHTP)
• Enhance, exchange, integrate, analyze,
disseminate, and visualize environmental
hazard and health outcome data
• Facilitate transformation of data to
“information” that is more usable/actionable
by researchers/stakeholders
• Identified 40+ databases/systems of interest
• CEHTP is a service organization
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Some CEHTP Principles, not all
• Environmental health tracking data should
be infused into as many relevant mediums
as possible
– Local, State, Federal, non-governmental
– Analog (e.g. paper) and digital (e.g. websites)
• CEHTP does not disseminate confidential
data
• Partners produce/consume data and services
with ease
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Map Visualization Principles
• CEHTP and/or system owners provide easy,
systematic, and standards-based access to
GIS data for dynamic interactive mapping
• CEHTP and/or system owners maintain
maximal control over look-and-feel of GIS
data
• CEHTP and/or system owners focus
resources on data within their jurisdiction
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How a Typical Interactive Map
Works
• Browser-based client has controls that take
zoom, pan, layer visibility, etc. parameters
and process into request to map server
• Map server receives request for map
• Map server processes request into an image
file
• Browser-based client displays image file
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Typical Map Server Paradigm
• Procure hardware, software, staff resources,
• Acquire (often buying) all GIS data to be
used in map service, import into platform,
configure rendering specifications for every
GIS dataset/layer
• Develop a customized browser-based client
to consume map service
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Evolving Map Service Paradigm
• Provide Uniform Resource Locator (URL) access
to commonly used GIS layers and, perhaps, give a
limited set of choices for visual rendering
• Interface specifications (URL parameters) for
requesting map image follow a consensus-based
standard
• OpenGIS Web Map Service (WMS): TerraServer,
USGS
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WMS URL Specs
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URI: Server name, directory, endpoint
Request: GetCapabilities | GetMap | GetFeatureInfo
BBOX: xMin, yMin, xMax, yMax
LAYERS: layer1, layer2
STYLES: style1, style2
FORMAT: image/jpeg
WIDTH: 400
HEIGHT: 600
SRS: EPSG:4326
Go to http://www.opengeospatial.org for more info
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TerraServer WMS Example
URL:http://terraserver.microsoft.com/ogcmap6.ashx?version=1.1.1&request=GetMap&Layers=DOQ&Styles=&SRS=EPS
G:26910&BBOX=547200,4182400,553600,4186400&width=800&height=500&format=image/jpeg&Exceptions=se_
xml
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Google/NASA Tip the Scale
• Google Earth and NASA Worldwind display
image tiles of basemap and satelite/aerial
imagery of the whole earth
• Physical air travel by humans decreases
• Google Local provides easy to use browserbased clients that incorporate emerging
WWW technologies (AJAX) and map
image tiles
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Google/Hackers Redefine BrowserBased Interactive Mapping
• Google Maps API makes it tremendously
easy to put dynamic maps with basemap
and high-res satelite imagery on any*
website with no non-standard plug-ins
– See http://www.google.com/apis/maps/
• Hackers figure out how to integrate WMS
content in Google Maps API
– See http://blog.kylemulka.com/?p=287
*Commercial sites must pay
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Tracking Trials/Tribulations
• Two partners to visualize CEHTP pilot project
data through custom interactive map server/client
implementations
• Stumbled through GIS data exchange, metadata,
and appropriate layer rendering
• Loss of control, miscommunication, map
server/client platforms too “closed”
• Need enterprise solution that makes integration
and standards a top priority
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Google API Drawbacks
• Map client can only display 2 overlapping
image tiles simultaneously (“Hybrid)
• Even if one of those tiles was non-Google
data (ie. your own tile data), image opacity
is not consistently or elegantly supported
across browsers
• Multiple tiles must be overlaid on serverside
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CEHTP Custom WMS Layering
• Develop server-side utility that overlays multiple
map server image tiles
• Support for consuming most popular map server
output (ie. ArcIMS, WMS, UMN MapServer,
ArcWeb services)
• Support for individual layer transparency and
opacity
• Support for server-side caching (~Google speed)
• Invocation interface is WMS (ie. standard URL
access)
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Recursion on the WMS LAYERS
parameter
• Recursion: “A programming technique in
which a function may call itself.”
• WMS LAYERS parameter is another WMS
request (or an ArcIMS request or a
MapServer request)
• HTTP encode each LAYERS parameter
• Opacity specified through STYLES
parameter
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Custom WMS request URL
Geek speak:
http://maps.ehib.org:8080/servlet/MapService?LAYERS=aims%28http%
3A//maps.ehib.org%3FSERVICE%3Drepro%26PORT%3D5300%26LAY
ERS%3D8%26FORMAT%3Dimage/gif%26STYLES%3Ddefault%26TR
ANSPARENT%3Dtrue%26reaspect%3Dfalse%29,wms%28http%3A//ims
.cr.usgs.gov%3A80/servlet19/com.esri.wms.Esrimap/USGS_EDC_LandC
over_NLCD_Merged%3FLAYERS%3DUS_NED_Shaded_Relief%3BUS
_NLCD%26FORMAT%3Dimage/gif%26STYLES%3Ddefault%26TRA
NSPARENT%3Dfalse%26reaspect%3Dfalse%29&SRS=EPSG:4326&ST
YLES=1.0,1.0&WIDTH=500&HEIGHT=500&FORMAT=image/jpeg&T
RANSPARENT=TRUE&EXCEPTIONS=INIMAGE&VERSION=1.1.0
&REQUEST=GetMap&BBOX=-122.3437,37.7185,-121.9921,37.9961
English: Alameda County preterm birth data on top of USGS
landuse and elevation data. Different servers, real-time
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Custom WMS response
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Content-Specific Custom WMS
(Pesticides)
• Use the WMS LAYERS and TIME parameters to embed
detailed data drill-downs on slicey dicey data URL:
LAYERS=ALL|C~ALL|lbs_sum&TIME=2003
• Statewide (ALL counties), ALL possible
pesticides/chemcodes, 2003 sum of pesticides within
County, Township, or Section (forced scale-dependency)
• URL: LAYERS=01|C~00385|applic_rt&TIME=1998
• Alameda County, methyl bromide, 1998 application rate
(pounds/acre)
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Bringing it Together
• Dynamic Map Service Integration Demo
• Special thanks to CADPR, CA West Nile
Virus Surveillance Program, and Center for
Vectorborne Diseases (CVEC) for providing
data (map services)
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Display Alameda County map service
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Add in West Nile Virus bird death
siting UC Davis service as layer
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Add in USGS landuse/elevation
WMS as layer
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Add TerraServer digital raster
graphics (DRG) WMS as layer
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Display Pesticides, WNV, and USGS
with opacity
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