Spatial Statistics on the Geospatial Web

Spatial Statistics on the
Geospatial Web
Matthias Hinz, Daniel Nüst, Benjamin Proß,
Edzer Pebesma

AGILE 2013 - Spatial Statistics on the Geospatial Web 2
Web Service (mediation layer)
Domain
Scientists
Scripting Environment
(software / languages)
Web Developer /
Admin
Heterogeneous
Audience
…
browser clients
community platforms
GIS-applications
services
Process Sharing
mobile devices
Geospatial Web

Run the script as a
web process
Upload script
to server
Enhance
script

The Annotation Concept
metadata
technical instructions
has name + parameter list
as code comments
locally and on a server

Four Annotation Types
general process description
dynamic inputs
process outputs
resources

1) General Process Description
# des: id = my42process, title= “my script”,
# abstract = “analyze 42 things”,
# author= “me”;
# myRuntime.des: id = …

# number for factorization
myFactor <- 10
2) Dynamic Inputs

2) Dynamic Inputs
myFactor <- 10
# in: id = myFactor, type = integer,
# title = “numerical factor”,
# abstract = “the number to be used
# for factorization”,
# value = 1,
# minOccurs = 0, maxOccurs = 1;

# off;
myFactor <- 10
# on;
# in: id = myFactor, type = integer,
# title = “numerical factor”,
# abstract = “the number to be used
# for factorization”,
# value = 1,
# minOccurs = 0, maxOccurs = 1;
2) Dynamic Inputs

3) Process Outputs
myResult <- myAlgorithm(1, 2, myDataSet)
# out: id = myResult, type = string,
# title = “factorized output”,
# abstract = “output number as text in
# scientific notation (a x 10^b)”;

4) Resources
# res: file1.data, file2.zip, file3.txt,
...;
# load auxiliary data
data1 <- foo("file2.zip")
data2 <- bar(“fixed_path/file3.txt")

Ignore flags
# off;
script.part.to = be_ignored_on_server()
# on;
script.part.to = run_on_the_server()

Application Example: WPS4R
Rserve
WPS Client
HTTP
GET /
POST
TCP /
IP
Web Admin Console
- Upload R scripts
- Manage processes
- Config parameters
WPS4R
XML
Requests /
Responses
R
HTTP
GET /
POST
User Administrator
Apache Tomcat Server
Processing
Service

Example: Interpolation
+Kappasys WPS-Client
Quantum GIS

WPS Process Description
[…] <ProcessDescription statusSupported="true"
storeSupported="true" wps:processVersion="1.0.0">
<ows:Identifier>org.n52.wps.server.r.Idw</ows:Identifier>
<ows:Title>Inverse distance weighted
interpolation</ows:Title>
<ows:Abstract>A simple interpolation carried out by R,
uses packages gstat, sp and rgdal</ows:Abstract>
<ows:Metadata xlin:title="R Script used for this process"
xlin:href="http://localhost:8080/wps/R/scripts/Idw.R"/>
<ows:Metadata xlin:title="Resource Directory URL"
xlin:href="http://localhost:8080/wps/R/resources" />
<ows:Metadata xlin:title="R Session Info"
xlin:href="http://localhost:8080/wps/R/sessioninfo.jsp"/>
<DataInputs> […]
# wps.des: id = idw,
# title = "Inverse distance weighted interpolation",
# abstract = "A simple interpolation carried out
# by R, uses packages gstat, sp and rgdal",
# author = "Matthias Hinz";

Example: Live WeatheR Plots
live sensor data
analysis on server
image output

Conclusion
annotation framework
script-based web processing
demo with open source framework
open approach
reproducibility

Outlook
security
provenance
rights
further implementations / tools
usability
bidirectional communication

Thanks for your Attention!

Resources
WPS4R Website:
https://wiki.52north.org/bin/view/Geostatistics/
WPS4R

Further Information

Server Environment Variables
if(exists(“server”) && server == TRUE){
srv.metadata = get_server_url();}

Annotated R script: IDW

[…]
<Input minOccurs="1" maxOccurs="1">
<ows:Identifier>attributename</ows:Identifier>
<ows:Title>Attribute name</ows:Title>
<ows:Abstract>Name of the attribute to be
interpolated, musst match the
observations</ows:Abstract>
<LiteralData>
<ows:DataType ows:reference="xs:string" />
<ows:AnyValue />
</LiteralData>
</Input>
[…]
# wps.in: attributename, string, "Attribute name",
# "Name of the attribute to be interpolated,
# must match the observations";

[…]
<DataInputs>
<Input minOccurs="1" maxOccurs="1">
<ows:Identifier>points</ows:Identifier>
<ows:Title>Observations</ows:Title>
<ows:Abstract>The point observations and
measurements
to be interpolated</ows:Abstract>
<ComplexData>
<Default>
<Format>
<MimeType>application/x-zipped-
shp</MimeType>
</Format>
</Default>
<Supported>
<Format>
<MimeType>text/xml;subtype=gml/3.0.0</MimeType>
<Encoding>UTF-8</Encoding>
<Schema>http://schemas.opengis.net/gml/3.
0.0/base/feature.xsd</Schema>
</Format>
<Format> […]

[…]<Output>
<ows:Identifier>result</ows:Identifier>
<ows:Title>Interpolated predictions</ows:Title>
<ows:Abstract>A raster file that contains
predictions for the observed area</ows:Abstract>
<ComplexOutput>
<Default>
<Format>
<MimeType>image/geotiff</MimeType>
</Format>
</Default>
<Supported>
<Format>
<MimeType>application/image-ascii-
grass</MimeType>
<Encoding>base64</Encoding>
</Format> […]
# wps.out: result, image/geotiff,
# "Interpolated predictions",
# "A raster file that contains predictions
# for the observed area";

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