GIS

Question 1

Type of GIS software

Answer 1

ArcGIS, QGIS, GEOMEDIA (used by local govt), Smallworld (used by utility companies)

Question 2

2 types of spatial features

Answer 2

Discrete (Roads, houses, wells) —> Vector
Continuous (Rainfall, elevation) —> Raster

Question 3

Discrete Geographic Features are better represent by what?

Answer 3

Georelational Vector Data Model (points, lines, polygons)

Question 4

What are the basic graphical elements of the vector data model

Answer 4

A point, a line, an area

Question 5

Basic rules with vector data

Answer 5

Each thematic object forms its own layer e.g. roads and railways are separate layers
Each layer can only have 1 type of feature (can’t mix points with polygons)

Question 6

Continuous Geographic Features are better represented by

Answer 6

Raster Data Model (grids and cells)

Question 7

An example of Raster Data Model

Answer 7

A digital elevation model (dem) is a digital terrain representation technique, where elevation values/topography are stored in raster cells. A DEM is very useful for hydrological modeling

Question 8

Other forms of Raster Data Models

Answer 8

Aerial photographs (Digital Orthophoto Quadrangle)
Satellite images

Question 9

What is the range of pixel values in a raster image and what do they represent

Answer 9

Between 0 - 255 representing the brightness of that cell
0: dark cell
255: bright cell

Question 10

How can remote sensing be used in GIS

Answer 10

Can be used to collect information about objects on the ground using Satellite or Plane based sensors
A form of primary data collection

Question 11

Why does vegetation reflects near IR

Answer 11

Because they’re really absorbing red, green and blue to convert into food, so IR is all that’s left over

Question 12

How can the number values be converted into a map with raster

Answer 12

Colors are a proxy for the number values

Question 13

What are the 2 types of analysis with GIS

Answer 13

Vector and Raster analysis

Question 14

What are types of vector analysis

Answer 14

Buffers, Overlays (union, clip, intersection), Network analysis (shortest path), location-allocation, spatial statistics

Question 15

What are types of Raster analysis?

Answer 15

Map algebra, DEM-specific, Time-series

Question 16

What is a buffer?

Answer 16

Polygons created by reclassification at a specified distance from point, line, area

Question 17

What is an overlay?

Answer 17

Most powerful feature of modern GIS
Place one “theme” (e.g. soils) over another (e.g. proposed parking lot) and check for soils which will cause problems of drainage for proposed parking lot (spatial correlation)
Another definition: the geometric intersection of multiple datasets to combine, erase, modify, or update features in a new output dataset

Question 18

How can I use buffers and overlays in GIS analysis?

Answer 18

Buffers can be combined with polygons overlays in order to analyze spatial information
e.g. Find all habitat areas of owls that are within 500 meters of country roads

Question 19

Is bird flu ecoregion based

Answer 19

Yes, 25 ecoregions (representing 8% of terrestrial surface area) accounted for 77% of cases

Question 20

What kind of information can vector data have?

Answer 20

Attribute information, which tells the database server what options, or attributes, to assign to the smart large object

Question 21

What is query attribute

Answer 21

The Query Attribute check identifies errors based on Structured Query Language query that can include one or more attribute values. Features or rows returned by the query are written as an error.

Question 22

Attribute queries in QGIS

Answer 22

One method to select features in a layer is to select features using an attribute query:
- Right click on the layer’s name on the Layer Panel
- Select Query from the

Question 23

Why are map projections complicated

Answer 23

It is difficult to to correctly express a 3D sphere in 2D

Question 24

Coordinate Systems

Answer 24

Coordinate systems - (x,y) coordinate systems for drawn through the center of the projection creates a new reference (x,y) for places in the globe. Map we know: Universal Transverse Mercator

Question 25

What are the basic elements of a map

Answer 25

Title, Map features, Legend, North Arrow, Scale Bar, Neat line