Analysys (Vector) - Completely GIS dan Remote Sensing tutorial - facegis.com
Analysis (Vector)

The ability to perform 'analysis' differentiates GIS from computer assisted mapping (CAD).
Both a GIS and a CAD can store data in layers but a GIS, rather than just displaying different layers, can perform analysis between them, both spatially and via attributes. (refer back to Lecture 1 )

### 1. Location query

yields attributes of that feature - a database function example attributes

## 2. Selection by attribute (e.g. where are all the pine stands)

Boolean Logic for queries (named after George Boole, a 19th century mathematician)

• Boolean function:
• A type of expression based upon, or reducible to a true or false condition.
• Logical Operators:
 = EQ Equal <> NE Not equal > GT Greater than < LT Less than >= GE Greater than or equal to <= LE Less than or equal to IN {1->200} Between the values of CN ' ' Contains the character string in the quotes

Example

• Boolean Operators (to combine items in a table)
• AND
• OR
• NOT
• XOR ( = either or, but not both)

These often require the use of brackets to avoid ambiguity in complex queries e.g.

type = pine AND age > 100 ... selects all old growth pine

type = pine OR type = fir AND age > 100.. selects any pine OR old growth fir

type = (pine OR type = fir) AND age > 100 .. selects old growth pine and fir

Examples of boolean logic using Boolean operators: (raster data)

 Maps A, B, and C represent the original map layers. The shade areas in D, E, F, and G represent where a condition is met for those locations. Map D shows : "Where is condition A but not B met?" e.g. Which areas have deep soils but NOT spruce? Map E shows : "Where are both conditions A and D met?" e.g. Which areas have deep soils AND spruce? Map F shows : "Where are either conditions B or C met?" e.g. Which areas have spruce OR good drainage? Map G shows : "Where is condition B or C, but not both, met?" e.g. Which areas have either spruce OR good drainage but NOT both?

Note: to examine attributes from separate vector data layers, these must frst be overlain (Overlay below)

## 3. Types of Analysis in GIS

Commonly used analytical tools in arcgis : append, buffer, clip, dissolve, integrate, intersect, union, erase

##### a. Database Query
- area, perimeter, values
##### b. Overlay

overlay: compare different layers and combines attributes: points lines polygons subdivision into new polygons

point and line in area overlay queries area - area overlay queries

##### c. Algebra
- modify by a given factor: add, subtract, multiply, divide
##### d. Transform
- modify by projection, datum or geocorrect, clip and erase
##### e. Classify
- dissolve, append, join, group, merge, generalize
##### f. Distance
- cost surfaces, distance to features, buffer buffer example
##### g. Network
- a system of interconnected lines - e.g. hydrological, transportation, utilities, animal migration: network analyst
##### h. Statistics
- filtering, smoothing, 3D surfacing
##### i. Modeling

- e.g. fire spread: based on fuel type, wind speed, direction, buffers, topography

Change : change effects, e.g. polar icebeetle spread  fires, volcanoes etc..

## 4. Review

Things you should know after finishing this lecture:
1. How is a database containing attribute tables essential for most GIS analysis?
2. Name four general types of analysis in GIS and give specific examples in two
3. What is meant by a boolean function
4. List the boolean operators
5. Why should a 'OR' query yield a larger result than a similar 'AND' query ?

Source: Source: http://www.gis.unbc.ca/courses/geog300/lectures/lect2/index.php