Midterm next Wednesday Midterm May start off with

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 – www. geodata. gov/

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/lec 06. html#nsdi

Barriers to Data Sharing (1) interoperability – will Arc. GIS 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 – 90 m, 30 m, 10 m – Oregon 10 m DEMs from buccaneer. geo. orst. edu/dem

Govt Agency Data Formats • Digital Orthophoto Quads (DOQs or DOQQs) – aerial photographs – camera orientation, terrain info. – raster images at 1 m resolution – 6 m positional accuracy at scale of 1: 12000 • Imagery – satellites – Landsat, SPOT, SPIN, etc.

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/lec 06. html#nsdi • Arc. Catalog – 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 servers worldwide and quickly rising – containing order 1 x 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, Alta. Vista – 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. s html • 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 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?