Fundamentals of GIS Lecture 8 Selected Public Data

Fundamentals of GIS Part 1 US Geological Survey Data Sources © 2009 Austin Troy

Fundamentals of GIS DLG • Digital Line Graphs; U. S. Geological Survey (USGS) • Derived from either aerial photographs or from manual and automated digitizing methods. • Digital representations of planimetric information: points, lines and areas • Full range of attribute codes, full topological structuring, have passed quality-control. © 2009 Austin Troy

Fundamentals of GIS DLG Summary © 2009 Austin Troy

Fundamentals of GIS Transportation layer Hypsography and Public land boundary layers © 2009 Austin

Fundamentals of GIS DLG Users Guides DLG Standards documentation available at http: //rockyweb. cr. usgs. gov/nmpstds/dlgstds. html Download, user guides, abstracts and metadata available for each DLG product at : http: //earthexplorer. usgs. gov Three DLG layers: hypsography, vegetation cover and roads © 2009 Austin Troy

Fundamentals of GIS DLG Category and Attribute Coding • Attributes come in coded for in PAT tables • To know what these codes signify, see web page http: //rockyweb. cr. usgs. gov/nmpstds/acrodocs/dlg 3/3 dlg 0798. pdf • Example: Vegetation Cover Layer, Item “Identity_lab” in PAT • • 0000 070 0101 070 0102 070 0103 070 0104 070 0105 070 0106 Outside area Woods or brushwood Scrub Orchard or plantation Vineyard Scattered trees Void area © 2009 Austin Troy

Fundamentals of GIS DLG-Medium Scale Example © 2009 Austin Troy

Fundamentals of GIS DLG-Small Scale Example © 2009 Austin Troy

Fundamentals of GIS DLG Availability • Go to http: //statgraph. cr. usgs. gov/viewer. htm

Fundamentals of GIS DLG Availability This shows vegetative coverage at 1: 24000 © 2009

Fundamentals of GIS Digital Elevation Models • Raster-based data structure for storing terrain data • Stores regular array of points in space with spot elevation values • Available for free from USGS, EROS Data Center • Continuous coverage of lower 48, Hawaii and limited portions of Alaska • Made from vector hypsography and hydrography data • Still used by some, but no longer maintained by USGS © 2009 Austin Troy

Fundamentals of GIS National Elevation Dataset (NED) • New-generation Digital Elevation model; is a complement, not a replacement to DEM • They are seamless (not tiled); can be downloaded as a single scene for a large area • Avoids terrain errors/ discontinuities at border of tiles and that they • Filtering process yields fewer “artifacts; ” improves quality of slopes and hydro modeling © 2009 Austin Troy

Fundamentals of GIS NED • Here is an example of errors generated in drainage

Fundamentals of GIS NED • Referenced to NAD 83 • Downloaded from seamless server as Arc. Grid files • Comes in one arc-second pixel size (~30 meters) for entire US • Comes in 1/3 arc second (~10 meters) pixel size for much of the US too • In a small number of areas is in 1/9 arc second (~3 meters) • Status maps available at http: //gisdata. usgs. net/website/usgs_gn_ned_dsi/viewer. htm © 2009 Austin Troy

Fundamentals of GIS NED 10 and 30 meter coverage: from Seamless. usgs. gov ©

Fundamentals of GIS NED • Download: rectangle-defined areas as seamless tiles from http: //seamless.

Fundamentals of GIS NED • NED homepage : http: //ned. usgs. gov • NED is free for FTP downloads of under 10 megabytes • Larger areas either have to be downloaded separately, or purchased as a bulk order. © 2009 Austin Troy

Fundamentals of GIS NED • For large areas, can purchase pre-defined zones on CD/DVD

Fundamentals of GIS National Land Cover Data © 2009 Austin Troy

Fundamentals of GIS National Land Cover Data • Available for 1992 and 2001 • 21 -category land cover classification scheme based on 1992 Landsat data • Comes in image format • 30 meter square spatial resolution • Available for free from http: //seamless. usgs. gov http: //gisdata. usgs. net/website/MRLC/viewer. php © 2009 Austin Troy

Fundamentals of GIS NLCD 2001 • 2001 classes are somewhat different from 1992 and are not designed to be compared for many class types. • E. g. “developed-open space”; many areas classed as low density urban in 1992 • Hence change analysis no recommended; however later 1992 will be reclassed to allow this comparison • NLCD 2006 is under plans as NLCD moves from being a mapping to a monitoring program © 2009 Austin Troy

Fundamentals of GIS NLCD 1992 and 2001 classification schemes Descriptions at http: //www. epa.

Fundamentals of GIS NLCD 2001 • Also includes layers of percent canopy cover and percent imperviousness. • These can be downloaded or viewed through a viewer online at http: //gisdata. usgs. net/website/MRLC/viewer. php canopy imperviousness © 2009 Austin Troy

Fundamentals of GIS NLCD: accuracy • Improved accuracy in 2001 • Accuracy tables for 1992 by region available at http: //www. epa. gov/mrlc/accuracy. html • 2001 accuracy tables still under development 1992 regions (EPA regions) 2001 regions/ reference points © 2009 Austin Troy

Fundamentals of GIS NLCD accuracy: 1992 © 2009 Austin Troy http: //landcover. usgs. gov/accuracy/

Fundamentals of GIS DOQs • Digital orthophoto quarter quadrangle • Also known as DOQQ • Old version is scanned photos, from the National Aerial Photography Program (NAPP) • One-fourth of a 7. 5 -minute USGS topographic map • 1 meter spatial resolution © 2009 Austin Troy

Fundamentals of GIS Digital Orthophoto Quadrangles Comes in three extents: • 3. 75 minute quarter quad (140 megs for color) • 7. 5 minute quad: limited availability, 140 megs for BW • Seamless DOQs from http: //seamless. usgs. gov © 2009 Austin Troy

Fundamentals of GIS The difference between an aerial photograph and an orthophoto • Aerial photo • Orthophoto – image displacement caused by tilting of camera and terrain relief – scale is not uniform – cannot measure distances on a photograph Light travels longer distance at scene edge: magnification © 2009 Austin Troy – rectified to remove nonconstant scale due to varying distance to camera – Also adjusts for elevation and tilt – Therefore possible to measure distances directly like on other maps – Can serve as a base map onto which other info may be overlaid

Fundamentals of GIS DOQ Documentation Download, metadata and user guides available at http: //edcsns 17. cr. usgs. gov/Earth. Explorer/ Standards Documentation available at http: //rockyweb. cr. usgs. gov/nmpstds/doqstds. html © 2009 Austin Troy

Fundamentals of GIS Digital Raster Graphics Scanned image of a U. S. Geological Survey (USGS) standard series topographic map The image inside the map neatline is georeferenced to the surface of the earth and fit to the Universal Transverse Mercator projection. The map is scanned at a minimum resolution of 250 dots per inch © 2009 Austin Troy

Fundamentals of GIS Used on-screen to collect, review, and revise other digital data, especially digital line graphs, DLG. DRG’s are available at www. gisdatadepot. com and at www. mapmart. com; some state GIS repositories have them too for free © 2009 Austin Troy

Fundamentals of GIS USGS Geographic Names Information System (GNIS) • This database contains information about almost 2 million physical and cultural geographic features in the United States. • The Federally recognized name of each feature described in the data base is identified, and references are made to a feature's location by State, county, and geographic coordinates. • Point coordinates are given in latitude/longitude • Often abstracts large features to a point © 2009 Austin Troy

Fundamentals of GIS GNIS Includes location, names and category of features such as: • Schools/universities • Churches/cemeteries • Airports/ports • Parks/recreation centers • Shopping centers • Stadiums/arenas • Theaters/auditoriums/cultural facilities • Country clubs/golf courses • Marinas/yacht clubs • Trailheads (some) • Rural fire stations (some) • Dams/reservoirs • Cities/incorporated areas (as points) © 2009 Austin Troy

Fundamentals of GIS GNIS Information, downloads and a query engine available at: http: //geonames. usgs. gov Files export as zipped text file. Can be imported into Excel The query engine can tell you the following about any named geographic feature you input: • Latitude/longitude • Elevation • Estimated 1994 population of cities • Feature type © 2009 Austin Troy

Fundamentals of GIS Part 2 Data from Other Sources © 2009 Austin Troy

Fundamentals of GIS National Hydrography Dataset (NHD) • Comes from both the USGS and the EPA • Surface water features: lakes, ponds, streams, rivers, springs • Nationally consistent • Order of linkages coded to allow for flow path analysis • Background info at http: //nhd. usgs. gov/techref. html • Resolutions from 1: 100 k to 1: 24 k © 2009 Austin Troy

Fundamentals of GIS NHD • Many analysis tools designed for this data. For instance: can find the path upstream or downstream from any point using NHD data and network analyst; flow reaches are numbered sequentially in order of flow to allow path analysis • Stream reaches encoded like addresses on a street • Connections encoded using topology • Other tools available at http: //nhd. usgs. gov/tools. html © 2009 Austin Troy

Fundamentals of GIS NHD • Download at http: //nhdgeo. usgs. gov/viewer. htm © 2009

Fundamentals of GIS NHD • Can extract by County/state. • Click on radio button of geography for clip • Use check marks to make layers visible in base map • Then Click on clip boundary (e. g. Chittenden County) in the map viewer © 2009 Austin Troy

Fundamentals of GIS NHD • Can then choose the resolution and the database type

Fundamentals of GIS NHD • Contents of Geodatabase: many feature classes with different purposes

Fundamentals of GIS USDA Data • USDA houses a number of data layers at

Fundamentals of GIS USDA Gateway Includes • CLU farm boundaries (not any longer, but SAL has it for VT)) • Hydrologic Units (8 and 12 digit) • NED elevation • Digital Raster Graphics • High resolution color orthophotos from 2003, 2004, 2006 (National Agriculatural Imagery Program) • Geographic Names • Cropland data layer (for some areas) • NRCS Soils data and soils tables • Climate Data (precipitation and temp) © 2009 Austin Troy

Fundamentals of GIS USDA Gateway Includes © 2009 Austin Troy

Fundamentals of GIS USDA Gateway Includes • Can Define clip regions by state or

Fundamentals of GIS Common Land Units • Farm field boundaries representing smallest contiguous unit of cultivated land • For farms in USDA programs • Much more accurate that “agriculture” category in NLCD land cover • Type of crop is unknown © 2009 Austin Troy

Fundamentals of GIS NAIP • National Agricultural Imagery Program • Digital Imagery, mosaiced by county, used by the NRCS and FSA to look at compliance with subsidy programs • Ortho-rectified, • Color, 1: 40, 000 scale • 2003 and 2004 © 2009 Austin Troy

Fundamentals of GIS SSURGO Soils Data • SSURGO: Soil Survey Geographic Data from NRCS • Soils data also at http: //soildatamart. nrcs. usda. gov/Defa ult. aspx • Metadata and standards available at http: //soildatamart. nrcs. usda. gov/SSU RGOMetadata. aspx • Entails both a polygon layer showing soils area boundaries, but also an Access Database of numerous soil attributes © 2009 Austin Troy

Fundamentals of GIS • SSURGO Soil Data Mart interface • Access—sample tables; there are

Fundamentals of GIS USDA Forest Service Data Gateway • For each National Forest includes layers like: boundaries, trails, roads, ranges for certain tree and animal species, and ecological regions http: //svinetfc 4. fs. fed. us/vectorgateway © 2009 Austin Troy

Fundamentals of GIS National Wetlands Inventory • • • From Fish and Wildlife Service Maps all class 1 and 2 major wetlands Available digitally for much of the country 1: 24, 000 or smaller Involves a complex taxonomy of wetlands codes available at http: //www. fws. gov/wetlands/_documents/g. NSDI/Wetlands. Deepwater. Habitats. Classification. pdf • Calculator at http: //www. fws. gov/wetlands/data/webatx/atx. html • Includes marine, estuarine, riverine, lacustrine and palustrine types © 2009 Austin Troy

Fundamentals of GIS NWI • Wetlands map interface at http: //wetlandsfws. er. usgs. gov/wtlnds/launch. html • Allows you to view online data and download • First shows status availability map: © 2009 Austin Troy

Fundamentals of GIS NWI • Can make PDFs easily © 2009 Austin Troy

Fundamentals of GIS NWI • NWI by wetland type overlaid on NHD streams layer

Fundamentals of GIS TIGER Topologically Integrated Geographic Encoding and Reference System Automates the mapping and related geographic activities required to support the decennial census and sample survey programs of the census bureau starting with the 1990 decennial census. The Census TIGER® system supports: Creation and maintenance of the digital geographic data base that includes complete coverage of the United States and its territories © 2009 Austin Troy

Fundamentals of GIS The TIGER system provides support for: • Creation and maintenance of a nation wide digital geographic data base • Production of maps from the TIGER® data base for all Census Bureau enumeration and publication programs • Allows for address geocoding • Can be integrated with Census attribute databases easily © 2009 Austin Troy

Fundamentals of GIS Accuracy and Attribution: • TIGER has good attribution, but poor accuracy • They are based partially on 1: 100, 000 DLG • Are often conflated • This is often used to assign the attributes from TIGER® data to 1: 24, 000 DLG data © 2009 Austin Troy

Fundamentals of GIS The TIGER files contain data describing three feature types: • Line Features 1. Roads 2. Railroads 3. Hydrography 4. Transportation and Utility Lines • Boundary Features 1. Statistical boundaries, such as census tracts and blocks 2. Local government boundaries, such as places and counties 3. Administrative boundaries, such as congressional and school districts • Landmark Features 1. Point landmarks, such as schools and churches 2. Area landmarks, such as parks and cemeteries 3. Key geographic locations, such as apartment buildings and factories © 2009 Austin Troy

Fundamentals of GIS TIGER line files and the demographic files Direct linkage using keys

Fundamentals of GIS For geographic files • ESRI: http: //www. esri. com/data/download/census 2000_tigerline/index. html Download 2000 U. S. Census TIGER lines files and demographic data • UC Berkeley Tiger Server: http: //sunsite. Berkeley. EDU/Gov. Data/info/tiger. html For attributes to 2000 and 1990 Census http: //factfinder. census. gov For data in intermediate years via the American Community Survey http: //www. census. gov/acs/www/ © 2009 Austin Troy

Introduction to GIS Fundamentals of GIS © 2009 Austin Troy

Fundamentals of GIS For continuing data updates, check the data links page at http: //www. uvm. edu/envnr/gradgis/supplement. html Here you’ll find links to many state level GIS online data repositories plus many of the ones mentioned here Another link is to map a network drive to \zoofilesgisdata where you’ll find: NAIP imagery, ortho photos, all VCGI data plus VTrans database, World data from ESRI, DRG topo maps, Street maps USA © 2009 Austin Troy

Fundamentals of GIS • The web site offers many layers through a browser VCGI

Fundamentals of GIS • Includes an interactive map browser for “clipping and zipping” data

Fundamentals of GIS Other sources for USGS data • www. mapmart. com – Allows users to choose tiles and layers with a geographic interface – Most public data are free, but , any others available for a price – Gives status maps – Can also buy bulk public data for a fee • www. gisdatadepot. com – Not as user friendly – Just a plain old interface that is hard to navigate – However, many free data layers and lots of scripts and extensions © 2009 Austin Troy