Midterm next Wednesday

Midterm• May start off with multiple choice

• Bulk will be short answer/short essay

• Lecture PPTs and your notes, readings in Longley et al., Zeiler

• Will not include – Labs or Arc Marine exercise

– Journal articles

Major concepts

• Representations• Object vs Field• Model, data model, analysis model• Data models

– UML terminology, basic procedure from• Reality --> conceptual --> logical --> physical

– Customized Arc GIS data models• For enterprise GIS

• Analysis Models– Binary, ranking, rating, weighted rating

Major concepts - cont.

• Geodatabase – what it is, why it’s important

• Topology, Spatial Analysis – what they are, why they are important, how they relate

• Object orientation– Identity, inheritance, encapsulation

• Data Sharing (barriers)

Concepts of Data SharingLongley et al., Chapter 11

NSDI ---> geodata.govGeospatial One-Stop

( GOS )• Who needs to share data?

– jurisdictions with common borders

– jurisdictions in a region

– private and public sectors

– local, state, and Federal agencies

– government and individuals

• Geospatial One-Stop– www.geodata.gov/

NSDI ---> geodata.govGeospatial One-Stop

( GOS )• State, local, private production of

geospatial data – loss of Federal monopoly, patchwork

– variable accuracy, level of detail

– the WWW

– everyone can be a producer, publisher, distributor ofgeospatial data

• See GEO 465/565 lecture #6– dusk.geo.orst.edu/gis/lec06.html#nsdi

Barriers to Data Sharing(1) interoperability

– will ArcGIS read Intergraph data?

– find a common format that both can read • output into the common format • input the common format

– is the common format the same as one of the GIS formats?

• if yes, only one conversion is needed • if no, two conversions are needed

– issues of format, syntax within ONE GIS

• Digital Line Graphs (DLGs)–vector topographic maps

–1:24,000, 1:100,000 ,1:10,000

Govt Agency Data Formats

• Digital Raster Graphics (DRGs)– raster topographic maps at

1:24,000

• Digital Elevation Models (DEMs)– raster elevation data

– 90m, 30m, 10m

– Oregon 10m DEMs from buccaneer.geo.orst.edu/dem

• Digital Orthophoto Quads (DOQs or DOQQs)– aerial photographs

– camera orientation, terrain info.

– raster images at 1m resolution

– 6m positional accuracy at scale of 1:12000

• Imagery– satellites

– Landsat, SPOT, SPIN, etc.

Govt Agency Data Formats

National Data Sharing (cont.)

• new high resolution commercial imagery • 1 m resolution• www.spaceimaging.com

Barriers to Data Sharing(2) how to describe what you need

– how to assess whether some data set fits the need?

Describing Data

• Metadata• Again, see GEO 465/565 lecture #6

– dusk.geo.orst.edu/gis/lec06.html#nsdi

• ArcCatalog– graphic thumbnail

– Tables

– FGDC format metadata

– ESRI format metadata

– XML format metadata

Issues with metadata?

• potential complexity– can be larger than the data set!

• investment to create– can be larger than the data set!

• carrots and sticks – FGDC’s "don't duck metadata"

Barriers to Data Sharing

(3) retrieval - large spatial data sets(4) national security - e.g., impact of 9/11(5) search engines

– how to know where to look on the WWW?– SAPs know where to look (more on this soon)

• National clearinghouse, www.geodata.gov/ or geographynetwork.com

• Regional and campus clearinghouses, • www.geo.oregonstate.edu/ucgis/datasoft.html• Google

Finding Data• How to find geospatial data on the WWW

– 10,000,000 servers worldwide and quickly rising

– containing order 1x 1015 bytes of information

– several servers contain more than 1 x 1012 bytes of geospatial information (terabytes)

• WWW search engines – Google, Yahoo, Ask Jeeves, Hot Bot, AltaVista

– send out “spiders” to find pages

– find the most important words in pages

– build a catalog of words

– how many pages contain the word "map”?

Finding Data (cont.)

• most important metadata element is geographic location – find me some data about area x

– only some areas have names • what if there's no name for the area you want?

– only some hits on a name lead to geospatial data

• search engines work on text, not GIS data sets

Some Searching Solutions

(1) Know where to look for a particular type of data – ortho.mit.edu contains a lot of DOQ data for

Massachusetts

– Valley library has free DOQ data for Oregon

– osulibrary.orst.edu/research/guides/maps/

maproom.htm

• USGS geospatial data is at the Eros Data Center, edc.usgs.gov

(1) Types of Data (cont.)

• Microsoft's Terraserver contains DOQs and Russian imagery– www.terraserver.microsoft.com

– >1 terabyte

– millions of hits per day

• EPA data, www.epa.gov– Corvallis ecoregion data at

www.epa.gov/wed/pages/ecoregions/

ecoregions.htm

• Again, only SAPs know this stuff ...

Some Searching Solutions (cont.)

(2) Go to a clearinghouse site • www.geodata.gov

– Over 300 servers

– Common metadata format, FGDC standard

– must select (multiple) servers to search

• Regional node of NSDI – Oregon Coastal Atlas, www.coastalatlas.net

Some Searching (cont.)

(2) Go to a clearinghouse site • many states have government-sponsored

clearinghouses – Oregon Geospatial Data Clearinghouse

– www.oregon.gov/DAS/EISPD/GEO/alphalist.shtml

• Campus clearinghouses– www.geo.oregonstate.edu/ucgis/datasoft.html

• ESRI-sponsored data sites – Geography Network, www.geographynetwork.com

Some Searching Solutions (cont.)

(3) Go to a digital library

a digital library whose contents are searchable by geographic location

• National Academy of Sciences report Distributed Geolibraries (1999)– using a map

– using a placename directory

– using coordinates

– what have you got about there?

Digital Libraries (cont.)

• specify area of interest as a box on a map • or one of millions of placenames• how do I know that the library is likely to

have what I want?– collection level metadata

– a description of the contents of a collection

Digital Libraries (cont.)

• OSU’s Oregon Explorer– oregonexplorer.info

• UCSB’s Alexandria Digital Library– www.alexandria.ucsb.edu

– Part of California Digital Library

– over 2,500,000 data sets

Some Searching Solutions (cont.)

(4) Issue-oriented site …

http://www.ushmm.org/googleearth/

Download and use Darfur KML from course lecture page

Who knows where Google will go with sites such as this?