Geotechnology and it's role in GIS Modelling

Application of GIS: Modelling

1. Applications of GIS Introduction Lecturer: Mohammad Forghani Mo. forghani@iau. ac.ir

2. Geotechnology GPS/GIS/RS Modeling involves analysis of spatial relationships and patterns ( numerical analysis ) Prescriptive Modeling Mapping involves precise placement (delineation) of physical features ( graphical inventory ) Descriptive Mapping Geotechnology is one of the three "mega technologies" for the 21st century and promises to forever change how we conceptualize, utilize and visualize spatial relationships in scientific research and commercial applications (U.S. Department of Labor) Why and So What Global Positioning System (location and navigation) Geographic Information Systems (map and analyze) Where is What (Berry) Remote Sensing (measure and classify) The Spatial Triad

3. GIS Evolution Computer Mapping …automates the cartographic process ( 70s ) Map Analysis …representation of relationships within and among mapped data ( 90s ) Where is What Why and So What Wow!!! Where Spatial Database Management …links computer mapping with database capabilities ( 80s ) Multimedia Mapping …full integration of GIS, Internet and visualization technologies ( 00s ) … GIS Modeling Course

4. Evolution of Map Analysis Geotechnology – one of the three “mega-technologies” for the 21 st Century (the other two are Nanotechnology and Biotechnology , U.S. Department of Labor )   70s Computer Mapping (Automated Cartography) 80s Spatial Database Management (Mapping and Geo-query) 90s Map Analysis (Spatial Relationships and Patterns)   Global Positioning System (Location and Navigation) Remote Sensing (Measure and Classify) Geographic Information Systems (Map and Analyze)   Spatial Statistics ( Numerical context) Surface Modeling (point data to continuous spatial distributions Spatial Data Mining (interrelationships within and among map layers) Spatial Analysis ( Geographical context) Reclassify (single map layer; no new spatial information) Overlay (coincidence of two or more map layers; new spatial information) Proximity (simple/effective distance and connectivity; new spatial information) Neighbors (roving window summaries of local vicinity; new spatial information)

5. GIS Modeling Is Important… Because most information has a spatial component Locations Networks Areas

6. GIS Modeling Is Important… It helps temporal reasoning as well

7. GIS Modeling Is Important… Social Factors Biodiversity Engineering Land Use Environmental Considerations It allows us to see the “whole”

8. Purpose of Models Simulate the real world Simplify the complex reality Explain underlying principles and relationships Predict the unknown in space or time Test hypothesis and scenarios

9. Components of a Model Assumptions starting conditions Elements variables Function relationships between variables Explanation logic behind the functions Prediction using functions to assess a situation under different conditions and at other locations or time

10. Scales of Model Binary/Nominal no quantity, names yes/no, presence/absence, on/off, true/false, 1/0 Ranking/Ordinal high/medium/low, excellent/very good/good/fair/poor Quantitative/Interval/Ratio absolute values, actual amount

11. Procedure of GIS Modeling Conceptualize the Model Formulate the Model Implement the Model Calibrate, Validate, and Refine Models

12. GIS Modeling Conceptualize the Model Project Design   (1) Identify the goal first   What is the problem?                   e.g., where to put ATM machines              e.g., where are the most appropriate places to cut old trees in a state park (2) Identify the factors that affect the solution For the location of ATM machines     factor 1:                  factor 2: factor 3:    For cutting old trees in a state park?

13. GIS Modeling Formulate the Model Methodology Design (1) Find the spatial data for each factor. Use surrogate data if direct data are not available For the location of the ATM machines              F1: data =                    F2: data =                    F3: data = (2) Identify spatial operators                  e.g., overlay, buffering neighborhood analysis, topographic analysis spread function stream function viewshed analysis network analysis, etc. For the location of the ATM machines Operator 1, 2, …

14. GIS Modeling Implement the Model Methodology implementation Collect the data           Run spatial operations          Map the results

15. GIS Modeling Calibrate , Validate , and Refine Models The output is nothing more than a pretty picture without acceptability assessment Go to field or use actual decision records as evidence                 Use aerial photo or satellite images as surrogate evidence              Set a small set of data aside and use it later to validate the model results                If all of above are impossible, Make sure all variables are significant for the model                 Make sure the model is appropriate

16. Three Types of Coupling Approaches: (1) Coupling GIS with a stand-alone modeling package by exchanging files: GIS is used mainly for pre-processing (data preparation) and post-processing (display/visualization). Requires an exchange format that is understood by both the GIS and the modeling packages (e.g., ArcView shapefile format). This is the easiest approach.

17. Three Types of Coupling Approaches: (2) Integrating GIS with modeling package using standards such as Microsoft’s COM and .NET that allow a single script to invoke commands from both packages: This is now a common approach (e.g., ArcObjects with COM-compliant programming languages).

18. Three Types of Coupling Approaches: (3) The entire model is executed by calling functions of the GIS using a single script. In other words, the model is embedded in the GIS (e.g., Model Builder in ArcGIS).