Process Models - GIS and Mapping - Lecture Slides, Slides of Geochemistry

In these Lecture Slides, the primary aim of the Lecturer is to illustrate the following key points : Process Models, Introduction, Systems Analysis, Process Models, Cartographic Models, Process Models, Inductive, A Posteriori, Deductive, Decision Support

Typology: Slides

2012/2013

Uploaded on 07/23/2013

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Introduction
GIS is often used to model processes. Two main
objectives:
To understand how the processes operate;
To predict the likely outcomes given particular
conditions.
Today we will do two things:
Look at process models in general
Discuss cartographic models
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Introduction

  • GIS is often used to model processes. Two main objectives: - To understand how the processes operate; - To predict the likely outcomes given particular conditions.
  • Today we will do two things:
    • Look at process models in general
    • Discuss cartographic models

Process Models

  • Process models attempt to model dynamic processes. May be: - A priori – driven by data rather than theory. Approach is basically inductive. - A posteriori – based on established theory. Approach is more deductive.
  • Objectives:
    • Systems analysis
    • Decision support

Gravity Models

  • Gravity models provide a good example of a process model.
  • Basic form:
  • The model may be fitted to determine the r and k parameters (calibration).
  • May need to distinguish between source and destination using exponents.
  • Many uses: e.g. migration, shopping trips, etc.

r ij

i j ij

d

m m

I k

Cartographic Models

  • A cartographic model is basically a flow diagram identifying the various coverages required for a particular end result.
  • For example, suppose we wished to identify suitable sites for a mountain cabin (DeMers).
  • There are several steps:
    1. Identify our criteria.
    2. Identify the data required.
    3. Identify the types of GIS operation required.

Weighting And Automation

  • In this example we use simple Boolean overlays – i.e. each criterion exercises a ‘power of veto’.
  • May be preferable to use fuzzy membership functions and/or weight the various criteria - i.e. weighted linear combination (WLC).
  • Can produce fewer or more suitable sites by adjusting the weightings.
  • May be useful to automate the model to allow it test ‘what if’ scenarios more readily. Could write a script or use a tool such as ESRI’s Model Builder.