Geography 463 GIS Workshop April 10, 2006

Outlines Project management principles Issues in system requirements Consider issues intrinsic to spatial data Choose a logical data model UML Class Diagram

Project management principles Part I. Project management principles

What is project? What is not? Projects Ongoing operations Definite beginning and end No definitive beginning and end Temporary in nature Ongoing Produces a unique product or service Produces the same product or service over and over Ending is determined by specific criteria Processes are not completed

The Triple Constraint Every project is constrained by its: Scope: what’s included and what’s not Schedule: anticipated time to complete goals Cost: budget allocated for project completion Project manager’s primary duty is to balance these competing constraints, while satisfying intended business need

The Triple Constraint of Project Management System requirements report helps you define the scope, cost, and timing constraints in advance. The image is retrieved from Tom Nolan’s lecture note

Issues in system requirements Part II. Issues in system requirements

System requirements and project management Can be thought of as implementation plan that allows the triple constraints to be recognized and balanced given information products identified from needs assessment report System requirements report will be composed of Data requirement Software requirement Hardware requirement Staffing requirement Timing requirement

Master Input Data List How is MIDL useful? Help you recognize requirements for data, software, hardware, staffing, and timing. Data: accuracy, data ready? Options for putting data into system (Buy? Outsourcing? In-house data creation?) Software: which functions are needed to put data into system? Hardware: decision on which workstation purchase is determined by data volume and computing complexity …. From p. 88 in Tomlinson (2005)

Data availability vs. data readiness Data availability: the date on which you can receive data from its source Data readiness: the date on which the data is in your system, processed, and ready for use in the creation of an information product Identify functions needed to put data available into the system (data readiness) Examples: to be ready for the system Satellite image requires file transfer and ID creation Paper map requires scanning, digitizing, topology editing, attribute editing, and so on Digital data would require a very little work

Priorities Help you manage the scope of projects What are important and what are less important information products and data? Occurs due to time/cost constraints This decision will be affected by the organization’s strategic plan/goals, thus consultants are not usually invited for this process

Before you estimate timing requirements, consider Data input timing Various options for putting data into system will affect timing Information product application programming timing Any scripting effort, what are steps involved? Required work hours? System acquisition timing Some hardware should be purchased/waited Training and staff issues Any training need? Make the use of existing staff or hire new persons

Consider issues intrinsic to spatial data Part III. Consider issues intrinsic to spatial data

Choosing the appropriate map projection Intended uses of information products Be aware of distortion of geometric properties (e.g. area, direction, distance) due to map projections Geographic area of interest Location of standard line/parallels Difference in datum? e.g. NAD27 vs. NAD83 Difference in measurement units? e.g. SPC vs. UTM

Choosing the appropriate map scale The appropriate map scale can be chosen based on resolution and error tolerance Resolution: the minimum amount of detail that can be mapped at a given scale; related to data requirements for information products Error tolerance: how much do your clients tolerate error? related to cost See p. 115 for the matrix for the choice of map scale

Topology editing Arc/info coverage Shapefiles Geodatabase Stored in feature attribute table Use BUILD/CLEAN command Shapefiles Non-topological model Geodatabase Topological rules are assigned to feature data set Topological rules within/between feature class can be defined Use topological editing tool; help you identify potential topological errors given predefined rules

Choose a logical data model Part IV. Choose a logical data model

Relational A collection of table (simple, ad-hoc) Table (entity) has attributes The relation between tables is created through a common attribute (remember how you perform table join?) Logical linkage: which keys needed? Most common logical model in GIS as well as hybrid form (file for features + relational table for attribute): e.g. arc/info coverage, shapefile

Object-oriented A collection of object (complex, natural) Object has attributes and operations Class is a collection of similar objects Database can be built using class hierarchy (e.g. some attributes of city database can inherit from supper class such as spatial objects) Model complex relationships Association: any Aggregation: weak form of whole-part relation Composition: strong form of whole-part relation Generalization: (e.g. secretary and employee)

Object-relational Compromise between relational model and OO model Extend relational data model so that good thing about OO (e.g. complexity, integrity) can be incorporated Maintain table with abstract data type Can use SQL E.g. Geodatabase

Choosing a logical data model Given continuous popularity of relational data model, relational data model can support the information products that involves a simple conceptual design If database requires handling of complex relationship, integrity and versioning, OO or OR will work better (e.g. facilities management) See p. 145 for which logical data model is suggested given data modeling situation

Part V. UML Class Diagram

What is UML? Acronym for Unified Modeling Language Standardized efforts that combine many years’ work on object-oriented analysis and design Use graphic notations (e.g. diagram) Intuitive; somewhere between natural language and programming language Anything to do with project management? Yes, user requirements modeling, planning, system design, database design, and so on whose tasks can be chosen from different kinds of diagram

Class Diagrams Associations Physical location (e.g., is next to) Direct actions (e.g., drives) Communication (e.g., talks to) Ownership (e.g., has) Satisfaction of a condition (e.g., works for)

Class Diagrams Association class Aggregation

Class Diagrams Generalization / Inheritance

Class Diagrams Class name Attributes Operations aggregation association generalization

UML Resources Software to use in the department Microsoft Visio or other drawing tools ESRI’s “Building Geodatabases with Visio” IBM Rational Rose literature on design w/ UML Introduction to UML Entity-relationship modeling with UML UML tutorials on the web