dept. of civil and environmental engineering and geodetic science college of engineering the ohio...
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Dept. of Civil and Environmental Engineering and Geodetic Science College of Engineering The Ohio State University Columbus, Ohio 43210 [email protected]
Data Acquisition ResultMap Composition
Analysis & ModelingF( )xyz=f(p1)xyz+f(p2)xyz+…+f(pN)xyz
Report
Data Acquisition ResultData OrganizationF( ) =Layer1+Layer2+ … + LayerN
ReportAnalysis & Modeling
Definition of GIS
Input Management & Analytical Modules Output
Data Acquisition - Geodetic Positioning - Remote Sensing - Field SamplingAnalog Data Conversion - Scan - Digitize
Management - Data Storage - Data Retrieval, Expand Edit, and Update - Query
Analytical Modules - Data Conversion - Data Manipulation - Modeling
Data Output - Visual Presentation - Analog Map Output - Reports
GIS Component
GIS Data Elements & Characteristics
Point Polygon
SurfaceLines
GridImage GIS Data Layers
Data Characteristics
Space – feature locations
Attribute – feature attributes, qualities & characteristics of geographic places.
Relationships Between Features
Time – additional spatial dimension
Data Types
Vector
- Based on mathematical function
- point, line, polygon, & surface
Raster
- Data present on a fixed grid
structure (matrix)
- image, grid
- Provides spatial relation and geometric shape of ground features- Serves as a foundation for data rectifications
- Nominal Data - categorized & named – class value - relates numbers to names - ex: tree species, soil type, parcel owner names- Ordinal data - classes are in a rank or order - ex: 1 - good, 2 – moderate, 3 - poor- Interval data - intervals between data values are meaningful - quantify differences - ex: elevation, F- Ratio data - measures a condition with a natural zero value - quantify proportions - ex: electromagnetic radiation, rainfall, slope
Data Organization
Coordinate System
Research Data Layers
Basemap
- Geographic coordinate system for small scale research.- Plane coordinate system for large scale research.
Research Data Layers
Basemap
Coordinate System
GIS Data Availability
GIS DATA
Conventional DataRemotely Sensed Data- Data driven from maps.- Statistical data from published tables.- CAD drawings.- Data from archives using the Internet or other network.- 4Ds: DRGs, DLGs, DEMs, DOQQs.
Spatial Only- B/W aerial photo- Panchromatic images- Radar image- GPS- Bathymetry- LIDAR
Spatial & Biophysical- Color aerial photo- Multispectral images- Hyperspectral image- Multiband radar image
DRG DLG DEM DOQQ
Inventory Operation
Measurement - Distance - Area/Size - Perimeter
Spatial Query - Graphic Query - Boolean Query: AND, OR, NOT
Database Operations - Lists & Reports - Relational Database
Inventory operation is to obtain information from existing data layers or databases
A=0.175km2
Measurement
Database operations
Spatial Query
P=1.5km
D=0.975km
Spatial Analysis
The basic operation involves: - Buffer operation - Overlay operation
Spatial Operations
Soil ObservationHydrologyLanduse
Soil 1 Corn
Soil 3
Soil 2Soil 4 SoybeanForest
Urban
Station3
Station 2
Station 1
River
Soil type and Landuse along the river, but within 150m radius of Station 2
Spatial analysis can be used to derive spatial relationshipsamong data layers
Network Analysis
The basic operation involves: - Locating routes - Determine which facility or feature is closest (allocation) - Modeling travel directions - Obtaining area around a site within a given distance or time
Service Area
Routing &Network Distance
Pollutant Transport
Time to Distribute
Effective Area
Network analysis is to solve the problem or model the behavior of a network structure by connecting lines, such as a transportation network or a stream network
3-D Analysis
Visualization - Provide 3-D view of spatial data
Terrain analysis - Viewshed - Elevation - Slope, Aspect, Hillshading - Watershed
DEM AspectSlope SinkStream
3-D analysis is to analyze spatial information in a 3-D perspective.
Space-Time Analysis
2-D View
3-D View
River Boundary Change in Time
X
Y
Time
XY
Observation PointsFunction in Time
T3
T2T1
Time
Y
X
Time is used as a spatial dimension (t).- The Space-Time concept is to model spatially- related events by using time as one dimension. This is so that the correlation between spatial movement and time can be derived by using conventional mathematical functions, such as distance, in 3D: Distance( )x,y,t = sqrt(x2+y2) Velocity( )x,y,t= sqrt(x2+y2)/t Space-Time Distance( )x,y,t= sqrt (x2+y2+t2)
X X
XX
YY
Tim
e
Tim
e
Change in Time Change in Time
- Data sets are registered to a common coordinate system- Geospatial data sets can be stored across a distance- Analytical tools are available for modeling environmental processes- GIS & remote sensing offer a way to study latitudinal gradients effectively