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 Sharing Longley et al., Chapter 11

NSDI ---> geodata.gov Geospatial 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 –

NSDI ---> geodata.gov Geospatial 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

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, or geographynetwork.com Regional and campus clearinghouses, Google

Finding Data How to find geospatial data on the WWW –10,000,000 servers worldwide and quickly rising –containing order 1x bytes of information –several servers contain more than 1 x 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 – –>1 terabyte –millions of hits per day EPA data, –Corvallis ecoregion data at ecoregions.htm Again, only SAPs know this stuff...

Some Searching Solutions (cont.) (2) Go to a clearinghouse site –Over 300 servers –Common metadata format, FGDC standard –must select (multiple) servers to search Regional node of NSDI –Oregon Coastal Atlas,

Some Searching (cont.) (2) Go to a clearinghouse site many states have government-sponsored clearinghouses –Oregon Geospatial Data Clearinghouse – html Campus clearinghouses – ESRI-sponsored data sites –Geography Network,

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 – –Part of California Digital Library –over 2,500,000 data sets

Some Searching Solutions (cont.) (4) Issue-oriented site … Download and use Darfur KML from course lecture page Who knows where Google will go with sites such as this?