GIS Fundamentals for Environmental Studies: Understanding Data Types in ArcGIS

1. GIS for Environmental Studies FA 2012 • Today’s lecture: • (action packed) • What is GIS? • Types of Data • What is ArcGIS? • File Formats Please note that portions of the material in this lecture come from Maribeth Price, author of your text.

2. Map layers can be combined to ask complex questions and do analyses. Points on the map can be linked to data.

3. What does GIS stand for? GIS data models • Geographic • Information • Systems Vector model Raster model

4. Vector model Features are stored as a series of x-y coordinates in a rectangular coordinate system. Many different coordinate systems may be used. Polygon Vertices Line Points Nodes Y X

5. Vector Data • Points: have x, y coordinates, no area, no length. • Lines: no area, have length, can have direction. Nodes on ends, vertices in the middle. • Polygons: have area, perimeter.

6. Features linked to data Each feature is linked to an entry in a data table containing information about the feature.

7. Feature classes A collection of similar objects with the same attributes States feature class Cities feature class

8. How do you choose what vector type to use? • What would you use for a city? • What would you use for a river?

9. Group Exercise: You are in charge of mapping the campus. The map will be used for the campus master plan to help plan where new buildings and roads will be, where trees should be planted, etc. Decide: • which data layers will you need (which will be most important) • what vector type would you use for each one (point, line, polygon) • name some attributes you would want with each layer

10. X, Y location X, Y location Columns Rows Raster data file N rows by M columns Georeferenced to earth’s surface The raster data model What is this? Hint – it is on our campus We’ll learn more about raster data later in the semester. We will be using data layers that are images before then True color image

11. GIS software programs • ESRI company (Environmental Systems Research Institute): ArcGIS, etc. • MapInfo: • Idrisi: • GRASS (Geographic Resources Analysis Support System)

12. ArcGIS basics: A history of products Arc/Info ArcGIS ArcGIS Desktop Arc ArcMap ArcPlot ArcView 3x ArcCatalog ArcEdit Info/Tables ArcToolbox GRID ArcInfo Workstation Coverages Shapefiles Geodatabases

13. $$$ArcInfo $$ArcEditor $ArcView ArcGIS functionality Same interface and programs More tools in the toolbox Three levels of functionality and cost

14. ArcGIS Desktop ArcCatalog ArcMap ArcToolbox

15. What is a layer? • Spatial data file • Associated properties • Held in memory in ArcMap • Used as inputs to functions/tools • May be saved as a file

16. Layer Properties Property tabs

17. Fig. 22. The metadata toolbar lets you create, view, and edit metadata for your layers. Create Edit Update Import Export Metadata • Contains information about data that people need to properly understand and use the data • Created with and copied with data

18. Data formats Coverages Shapefiles Geodatabases

19. Coverages Multiple feature classes Topological features Many files Info tables From Arc/Info B A Topology is information stored about spatial relationships between features. Polygon A is composed of a label and two arcs. Polygon A is adjacent to polygon B and shares one common arc.

20. Shapefiles Coincident boundary Shapefiles in Windows Explorer Shapefiles in ArcCatalog • One feature class • Multiple files • Simple features • No topology • Dbf tables • From ArcView

21. Geodatabases Single file Multiple feature classes Access database technology Feature datasets Simple and topological features Validation rules Customized object behavior

22. Other types of data Rasters Tables Layer files CAD Drawings

23. Pop Quiz – what is the data format of each item in this clip from ArcCatalog?

24. Data layer vector type attributes