1. Re-introduction to GIS
ENVS 420
Re-introduction to GIS

2. What is a GIS
The systematic integration of technology, geographic core ideas, and specialized knowledge applied through procedures to compile, store, manipulate, and analyze spatial and temporal data, and to communicate these data and information through some form of geovisualization.

3. What is a GIS? Smaller/ practical definitions
‘Layers’ of information about a place that give a better understanding of that place.
An information system designed for data referenced by geographic coordinates.
A set of tools for analyzing spatial data

4. What distinguishes GIS from other technologies?
GIS used to manage and analyze spatial data  
GIS predicates processing functions on geographic location  
types of data involved
types of users and user support required
specific sub-systems applied
works at geographic scales
 how the tools are applied  

5. What are Spatial Data? Scale of Data Local Global
Information about a specific area, location data.
Spatial data types include feature classes, shapefiles, coverages, grids, rasters, images, surfaces or event tables.
Scale of Data
Local
Global

6. Attributes
Features
Records

7. Continuous (grid, raster) vs. discrete (vector) spatial data
Grain/minimum mapping unit vs. extent

8. Continuous Features: Elevation Rainfall Population Landcover
Raster Vector
Continuous Features:
Elevation
Rainfall
Population
Landcover

9. Discrete Features: Raster Vector Fire Hydrants Cities Sample Sites
Point Features
Fire Hydrants
Cities
Sample Sites
Line Features
Streets
Rivers
Pipeline
Area Features
Land Parcels
City Limits
Census Tracts
Lakes

10. Raster and Vector Combined
EGEO-350 Fall 2009

11. Spatial Scale Extent

12. Spatial Scale Grain Fine Grained Coarse Grained
The minimum resolution of the data. In raster lattice data, the cell size; in field sample data, the plot size; in imagery, the pixel size; in vector GIS data, the minimum mapping unit.
Fine Grained
Coarse Grained

13. What Can A GIS Do? Location Patterns and Relationships
Areal Measurements
Trends
Neighborhood
Analysis
Modeling
Queries

14. Location Where is Feature X? What exists at a specific location? East
E.g., What feature is at 5 units South, 11 units East?
East 9 10 11 12 13 3 X 3
South 4 4 Z 5 Y 5 9 10 11 12 13

15. Areal Measurements
5 Km X Y
Distance
Perimeter
Area/Size
30 Km
10 Km2

16. Patterns and Relationships
Does Feature X occur in a pattern?
Yes, in a line from NW to SE.
Is there a relationship between X and Y?
Yes. Y is always close to X. Z X Z Y X Y Y Z X Z

17. Patterns and Relationships
What other spatial or functional patterns exist?
Feature Z is always near a border and increases in size from west to east. Z X Z Y X Y Y Z X Z

18. Neighborhood Analysis
Adjacency
B is adjacent to A
C is adjacent to B
C is not adjacent to A
Connectivity
B is connected to A
C is not connected
Proximity
B is within 2 Km of C A B C A B C
2 Km A B C

19. Trends How did items A, B, C, and D change from 1980 to 1990? A C
A increased size
B decreased size; moved
C changed shape
D Showed-up
1980
1990 B A A B C C D

20. Modeling Generalization Model Rice Cane Fruit Pine Bare Brush Mix
Agriculture
Vegetation

21. Modeling Reality: Model: Sea 4 mountain ranges
Rivers drain shortest path to Deep Blue Sea
Central Mountains control path of longest stream
Other streams drain into it
Model:
Simplification
Generalized reality
West Mts.
North Mts.
Mts.
Mts.
Central Mts.
Mts.
East Mts.
Deep Blue Sea
Mts.
Sea

22. Modeling What-if scenarios:
Major stream takes long route around mountain range. Other streams feed directly into it and are very short.
New mountain position. Major stream takes short route to ocean. Other streams are longer. One rerouted to secondary stream.
Mts.
Mts.
Mts.
Mts.
Mts.
Mts.
Mts.
Mts.
Sea
Sea

23. ArcGIS Can Employ Many Types of Data
Shapefiles
Coverages
CAD
Grids
Images
Geodatabases
Feature classes
Tables
Rasters

24. A Shapefile Consists of Many Files
Each SHAPEFILE consists of at least three files:
Streets.shp
Streets.dbf
Streets.shx
These are the three you will see with all shapefiles, but can include: .sbn, .shn, .met, .avl, .prj files...
You need all of the associated files to use in ArcGIS

25. Coverages and GRIDS Consists of Folders
Each Coverage consists of two folders.
A folder that has the name of the file and an Info folder.

26. GEODATABASES ArcGIS Relational Database Management Systems
‘File Geodatabase’ or ‘Personal Geodatabase’ Shell
‘Data Model’ or a ‘Schema’ – A logical construct for the storage and retrieval of data.
It’s how the GIS organizes within a database, the data we use for analysis.
ArcGIS Geodatabase
Exportable Macro Language (XML files)

27. Important Aspects of RDBMS
Data definition language
Data dictionary
Quality Control
Updates
Metdata
Query
Relational
Not Excel
Interoperable

28. Queries -- Attribute Data
Attribute description
What are the attributes of record 2?
Where do certain conditions exist?
Who owns property with high soil fertility? (Field) - Homer and Flanders

29. Example of a Complex Query
Relational Database
Example of a Complex Query
Site Suitability (set of conditions)
Which property has:
Area: > 40,000 Ha
Owner: Not Flanders
Tax code: B
Soil quality: High 1 3 6 2 4 5

30. Relational Database Stand Table Potential Vegetation Table
Landform/Topography Table

31. Why Do Images Have an Associated World File?
The most common image formats are:
.Tiff or .tif
.jpg or jpeg
For an image to be read into ArcGIS, and used with other layers it must have an world file.
World Files
.tfw (For Tiff or Tif)
.jpgw or jpeg (For jpg or jpeg)

32. Why do files have Different Appearances in ArcCatalog vs Windows Explorer?

33. Why is it Better to Use ArcCatalog to Move GIS Files?

34. ArcMap works from Project Files (*.mxd documents)
Mxd documents are the ArcMap project files. Mxd stands for (multi-xml documents).
ArcMap stores the path and working properties of the data files in a project file (.mxd).
This makes it important to keep your data with your ArcMap file (.mxd file).

36. This is what the .MXD file looks like..
The .mxd stores the path to the datafile

37. Things to Keep in Mind for Your Own GIS Projects (.mxd)
Create a data manage system to organize and store your data files for efficient retrieval and analysis!
Keep your .mxd file within your data management system!
Before saving in ArcMap, go to File Properties and check on the store relative paths checkmark!
Move the entire folder to someplace you will have access later (U:drive or Thumb Drive)
Do not rely on things in the C:/temp Drive, it does get deleted.