Spatio-temporal asset management in a database of glacier change

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18 Νοε 2013 (πριν από 3 χρόνια και 6 μήνες)

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Spatio
-
temporal asset
management in a database of
glacier change


David Percy(1)

Geospatial Data Manager

PSU Geology Department

Co
-
authors: Eric Hanson(2), Darrell Fuhriman, Cris Holm(2),
William Garrick(2), Chris LeDoux(1), Matt Hoffman(1) and
Andrew Fountain (1)

(1)Dept of Geology, Portland State University

(2)Academic and Research Computing, Portland State University


Funding by NSF, NASA, USGS and Portland State University

Three main points


Hierarchical spatial structure: spatial
ontology? Initially avoided due to
complexity of relations, eventually
imposed top
-
down


RDF for database


Temporal topology

Mt Hood, Oregon


Eliot Glacier

The challenges

Glaciers may have many sources that
describe their state.

Glaciers change over time and these
various data sets need to be connected to
the currently displayed outline.

Over 8000 polygons showing extent of
perrenial ice and snow. No one wants to
touch each of these to associate them
with assets. Need a solution to link space
and time with data base of assets.

Components of Open Source

Web Mapping

The new “LAMP”



L


Linux


A


Apache


M


MySQL


P


PHP



L


Linux


A


Apache


M


MapServer


P


PostGIS


Metadata

Vector Data

Asset id (PK)

Asset type desc

Metadata id (FK)

Asset name

Shape

File name

File location

Source scale

Year start

Year end

Glacier database

Web version


Aggregated data

Glac_num

Centroid lat

Centroid long

Max elev

Min elev

Mean elev

Mean elev area weighted

Mean aspect

Region

State

HUC

Metadata id (FK)

File name

File location

Source scale

Cell size

Year start

Year end

Glac_num (PK)

Asset id (PK)

Glacier asset
mm

Various

Asset id (PK)

Asset type desc

Metadata id (FK)

Asset name

File name

File location

Source scale

Cell size

Year start

Year end

Glacier


polygon

Moraine


polyline

HUC


polygon

GNIS


point

Oblique photo

Asset id (PK)

Asset type desc

Metadata id (FK)

Asset name

File name

File location

Year start

Year end

Aster

Asset id (PK)

Asset type desc

Metadata id (FK)

Asset name

File name

File location

Year start

Year end

Cell size

Quality

Img acquired month

Ref id

<fields>


References

Raster Data

DRG

DOQ

DEM

Glac_num

Centroid lat

Centroid long

Max elev

Min elev

Mean elev

Mean elev area weighted

Mean aspect

Region

State

HUC

Metadata id (FK)

File name

File location

Source scale

Cell size

Year start

Year end

Glacier

Asset

Asset id (PK)

Region_id

Asset type desc

Metadata id (FK)

Asset name

File name

File location

Source scale

Cell size

Year start

Year end

Asset_Props

Prop_Id

Asset id (PK)

Name

Value

Regions

Region_Id

Geometry

Description

Region_level

Parent_id

Metadata

1946

1936

Temporal topology

1907

Past

1924

1907

1924

1936

1956

1946

1986

1956

1936

Future

1924

User says "show me all glaciers from 1940"


By having stored the temporal topology, ie prior year date and

subsequent year date, we can find the closest object in the following three

ways:

Past only

( [Year] <= 1940) and ([Subsqunt_yr] > 1940 )

Closest Temporal buffer

(( [Year] + ([Subsqunt_yr]
-

[Year]/2)) >= 1940) and

(([Year]
-

([Year]
-

[Prior_yr]/2)) <= 1940)

Gives the temporal mid point between two spatially referenced objects

Conservative Temporal buffer

(( [Year] + ([Subsqunt_yr]
-

[Year]/1.5)) >= 1940) and

(([Year]
-

([Year]
-

[Prior_yr]/3)) <= 1940)

Gives you 2/3 past, 1/3 future

This can be parameterized!

Conclusions


Hybrid RDF databases are viable, useful
and in production NOW.



The big question is how granular to get
with RDF? For example individual vector
data? Performance issues...



Temporal topology may be the way to
solve certain problems WRT spatio
-
temporal asset management


Future


WMS and WFS services to expose “stovepipe” to
outside access


http://geospatial.research.pdx.edu/cgi
-
bin/mapserv?map=/disk/mapserver/maps/percy/glaciers_wms.map&service=wms&request=getcapa
bilities


Google Earth?


Query results dynamically to KML...


Example:

http://geospatial.research.pdx.edu/~bjpd/usgs/ngm_quicksearch.html