Vector Data Model (Midterm 2)

Front 1

2 Steps to Storing Geographic Data

Back 1

1. Uses points and their (x,y) coords to represent spatial features (points, lines, polygons)

2. Organized geometric objects and their spatial relationships into digital files that can be processed.

Front 2

Representing Spatial Features

Back 2

Point Feature - 0 dimension

Line Feature - 1 dimension

Area Feature - 2 dimension

Front 3

Topology

Back 3

Study of geometric objects that remain invariant under certain transformations.

"if it is connected it is connected"

Front 4

Graphs

Back 4

used to model relationships between objects.

Front 5

Arcs (Edges)

Back 5

Are used to represent relationships.

(can be directional or not). Lines and Points!

Front 6

Nodes

Back 6

Used to represent objects.

Front 7

Adjacent Nodes

Back 7

2 nodes are adjacent if they are joined by an edge.

Front 8

Incident

Back 8

if a node and an edge are joined.

Front 9

Adjacency Matrices

Back 9

represented as 1's and 0's where the 1's represent that nodes are connected.

(read left to right)

Front 10

Incidence Matrices

Back 10

represented as 1's and 0's where the 1's represent that nodes are connected.

if something is coming in then the 1 becomes negative.

(read left to right)

Front 11

Why Topology

Back 11

Data Quality and Integrity

rules coded into the adjacency and incidence matrix can be used to ensure that the coords of points are accurate.

Front 12

Efficient Data Storage

Back 12

Reduced redundancy and eases editing.

Front 13

Coverage Data Model

Back 13

Geographic coordinates and attributes are stored in separate but linked files.

Front 14

How directionality is stored in Line Coverage

Back 14

Based on clicking order, 0 separates internal/external boundaries. (Insert Image)

Front 15

Composite Features

Back 15

spatial features better represented as composites of point, line, or polygon objects.

(creating something more out of vector data with vector data).

Front 16

DriangulatedIrregular Network (TIN)

Back 16

None overlapping triangles with constant gradients.

Smaller triangles where elevations change rapidly.

Implemented as a Terrain feature dataset.

Front 17

Regions

Back 17

ArcGIS data model for storing overlapping or disjoint polygons.

Front 18

Shapefiles

Back 18

Non-topological formats for points, lines and polygons.

Geometries for each feature are stored individually.

Faster display time but prone to topological errors.

Front 19

Mandatory Files

Back 19

.shp - the feature geometry itself

.shx - a positional index of the feature geometry

.dbf - attribute database

Front 20

Optional Files

Back 20

.prj - projection file

.xml - meta data

Front 21

Object-Oriented Software Design Concepts

Encapsulation (data hiding)

Back 21

data and methods (operations, behavior) bound together in a single object accessible only by invoking methods.

Front 22

Object-Oriented Software Design Concepts

Inheritance

Back 22

Objects can inherit properties and/or behavior from a parent (class).

Automobiles have steering wheels --> Buses and Trucks can inherit steering wheels.

Front 23

Object-Oriented Software Design Concepts

Polymorphism

Back 23

The same message sent to different objects can result in different behavior.

Front 24

Object oriented data modeling (3 things)

Back 24

Treats spatial data as objects that can represent a spatial feature (road, timber stand) or an object without spatial representation.

Stores both the spatial and attribute data of spatial features in a single system.

Allows a spatial feature (object) to be associated with a set of properties (attributes) and methods (behavior).

Front 25

Spatial Features

Back 25

Behave the same no matter what they represent.

Front 26

Object "Classes"

Back 26

allow an analyst to ascribe unique behavior to a class of features and bundle the feature with its attributes and behavior into one cohesive "object"

Implemented in ArcGIS as tables with special columns.

Front 27

One to One Relationships

Back 27

Association, Aggregation, Composition, Inheritance

Front 28

Association

Back 28

represents a relationship between two or more objects where all objects have their own lifecycle and there is no owner.

Front 29

Aggregation

Back 29

A specialized form of Association. Where all objects have their own lifecycle, but there is ownership.

Front 30

Composition

Back 30

A specialized form of Aggregation. Where child objects do not have their lifecycle without parent object.

If a parent object is deleted, all its child objects will also be deleted.

Front 31

Inheritance

Back 31

A subclass, mechanism of acquiring the features and behaviors of a class by another class.

Front 32

Universal Modeling Language (UML)

Back 32

visual language for conceptual diagrams like entity relationship diagrams, but with:

Class diagrams, classes and objects, and relationships.

Front 33

Features Class

Back 33

Stores spatial data of the same geometry type (a table).

Front 34

Feature Dataset

Back 34

stores feature classes that share the same coordinate system and area extent. (a set of related tables)

Front 35

5 Steps to Build a Geodatabase

Back 35

1) model the user's view of data.

2) define objects and relationships (ER diagrams, UML)

3) select geographic representation (vector?, raster?, network?, TIN?)

4) match to geodatabase elements (geometry type of discrete features)

5) organize geodatabase structure (topology, coordinate system, integrity rules)

Front 36

Geodatabases (Why?)

Back 36

1) hierarchial structure useful for data organization and management (different feature datasets for different geographic regions)

2) take advantage of object oriented programming for adcanced analysis functions

3) topology rules applied "on the fly"

4) ArcObjects --> custom objects and analysis.