Gis Study Guide

Front 1

What Band is the blue Band and what are the characteristics?

Back 1

TM band 1

Hint 1

Useful for detecting manmade features and mapping coastal waters. Can be affected by atmospheric haze, and therefore less useful than other bands.

Front 2

What band is the green band and what are its characteristics?

Back 2

TM band 2 or SPOT band 1

Hint 2

Useful for detecting manmade features. This wavelength is reflected by vegetation, but not useful for discrimination between vegetation types.

Front 3

What is the red band and what is its characteristics?

Back 3

TM band 3 SPOT band 2

Hint 3

Useful for detecting manmade features. Useful for discriminating between plant species, and determining soil and geological boundaries.

Front 4

What is the near infared band and what is its characteristics?

Back 4

TM band 4 and SPOT band 3

Hint 4

Very responsive to the amount of biomass. Useful for vegetation/soil and land/water boundaries and crop identification.

Front 5

What components does GIS include?

Back 5

Data acquisition, representation, spatial analysis, ethical and social issues

Front 6

What is GIS?

Back 6

An integrated system used to display, store, manage ad analyse data about objects on the earth.

Front 7

What are the three primary functions of GIS?

Back 7

Visualization: Gain info and see relationships
Geodata management: organizing data and make it useful
Analysis: helps to answer questions and make decisions

Front 8

What are the three primary functions of GIS?

Back 8

Visualization: Gain info and see relationships
Geodata management: organizing data and make it useful
Analysis: helps to answer questions and make decisions

Front 9

What is a feature?

Back 9

Represents a real world object on a map
ex: points lines and polygons

Front 10

What is a layer?

Back 10

A collection of features

Front 11

What is scale?

Back 11

relationship between the size of features on a map and their actual size in the real world.

Front 12

What is the geographic coordinate system?

Back 12

Uses a three dimensional ellipsoid to define locations on the earth. Includes an angular unit of measure, a prime meridian and a datum. A location can be defined by its longitude and latitude value. Not a DATUM

Front 13

What is a datum?

Back 13

defines the position of the spheroid relative to the center of the earth.

Front 14

How would you convert this into decimal degrees? 151 degrees 12 minutes and 66 seconds?

Back 14

151+12/60+66/3600

Front 15

What are Geographic Coordinates?

Back 15

A global coordinate system is the most accurate system for representing the location of a point of the earth's surface. Latitude and longitude are expressed as degrees, minutes and seconds.

Front 16

What are the drawbacks of the geographic coordinates?

Back 16

Must know the shape of the earth (model). At the equator 1 degree is equivelant to 111Km. At the poles 1 degree longitude is 0km!

Front 17

What is a map projection?

Back 17

To project maps of the earth's spherical/elliptical surface onto a flat surface (two dimensional cartesian coordinate plane). A projected coordinate system is always based on a geographic coordinate system.

Front 18

What types of map projections are there?

Back 18

Cones, Cylinders, planes

Front 19

Types of map projected coordinate systems

Back 19

Universal transverse Mercator (UTM)
Map Grid of Australia (MGA), mercator projection, transverse mercator projection

Front 20

What is the Australian Map Grid (AMG) and map grid of australia (MGA)

Back 20

based on a UTM coordinate system.
The coordinates are easy to recognize:
x (easing) has 6 digits
y (northing) has 7 digits
based on meters

Front 21

What are the advantages of Universal Transverse Mercator?

Back 21

Frequently used, useful for calculating accurate within zone distances and areas, consistent

Front 22

What are the disadvantages of Universal Transverse Mercator?

Back 22

Require an easing, northing and a zone number, the system cannot be used close to the poles because distortion is to great, the rectangular grid causes axes in adjacent zones to be skewed making it hard to work across boundaries, no mathematical relationship between the coordinates in one zone and the next.

Front 23

What are common overlay methods?

Back 23

Intersect, Union, symmetrical difference

Front 24

what is the output of intersect

Back 24

only that area where to inputs intersect

Front 25

what is the output of uniont

Back 25

all area of inputs including intersected area

Front 26

symmetrical difference output?

Back 26

all area of inputs not including intersected area

Front 27

How many degrees is a longitude zone?

Back 27

6 and zone 1 is at 180 degrees west

Front 28

What is the math work for the zone sydney is in ?

Back 28

Longitude= 153 so 153/6=25
another 180 degrees to the greenwich line on the western side which = 180/6 =30 zones
30+25=55 zones before sydney, sydney =56 zone

Front 29

What is clip?

Back 29

The spatial extent of one layer can be used to clip the area of interest from another layer. The feature attribute table for the output coverage contains the same items as the input coverage attribute table.

Front 30

What is dissolve?

Back 30

Joins objects that are adjacent spatially and have matching non-spatial attributes. ARCGIS calls this method dissolving

Front 31

What is included in map scanning and vecotorisation?

Back 31

1. Prep of a special map.
2. Scanning the input map to digital format.
3. Filtering of raster image to remove "noise" or anything unwanted
4. Thinning of groups of pixels
5. linearisation or vectorization of neighbouring pixels
6. smoothing of resultant vectors

Front 32

How many satellite signals are required to define the location on the earth surface?

Back 32

3

Front 33

How many satellite signals are required to determine the position of a 3-D elevation above earth surface?

Back 33

4

Front 34

Accuracy of GPS Measurment depends on?

Back 34

Atmospheric conditions, GPS satellite coverage, obstructions, multipath error(gps signal bounce of a hard surface before it reaches the receiver)

Front 35

What is a more accurate positioning?

Back 35

Differential GPS

Front 36

What are the two types of primary raster data?

Back 36

aerial photography and remote sensing

Front 37

How do you create a new shape file?

Back 37

1. Create a shapefile from catalog panel
2. Define a file name, feature type, and coordinate system.
3 Draw the shapefile feature using editor tool in arcmap.
4. edit its attributes from the attribute table

Front 38

What happens when you convert vector data to raster data?

Back 38

A grid is superimposed and each cell is assigned to a polygon. A grid is superimposed and appropriate cells are coded to show the presence of the line or point.

Front 39

Accuracy of GPS Measurment depends on?

Back 39

Atmospheric conditions, GPS satellite coverage, obstructions, multipath error(gps signal bounce of a hard surface before it reaches the receiver)

Front 40

What is a more accurate positioning?

Back 40

Differential GPS

Front 41

What are the two types of primary raster data?

Back 41

aerial photography and remote sensing

Front 42

How do you create a new shape file?

Back 42

1. Create a shapefile from catalog panel
2. Define a file name, feature type, and coordinate system.
3 Draw the shapefile feature using editor tool in arcmap.
4. edit its attributes from the attribute table

Front 43

What happens when you convert vector data to raster data?

Back 43

A grid is superimposed and each cell is assigned to a polygon. A grid is superimposed and appropriate cells are coded to show the presence of the line or point.

Front 44

What happens when you convert raster data to vector data?

Back 44

boundaries are located between cells of different classes and the coordinates of boundaries stored. The center of the cell is stored. Lines need special algorithms to establish connectivity.

Front 45

what is a map?

Back 45

A map represents geographic features or other spatial phenomena by graphically conveying information about locations and attributes.

Front 46

What are the properties of a map?

Back 46

scale, resolution, accuracy

Front 47

Why is scale important in terms of accuracy of data?

Back 47

accuracy of features, accuracy of measurement, visualisation, relationship between features

Front 48

What is the general rules of scale?

Back 48

1. where possible use data captured at the same scale
2. work with data at the large scale
3. always be aware that the info produced is scale dependent.

Front 49

what is resolution?

Back 49

smallest unit of area that can be identified from the map.
it refers to how accurately the location and shape of a map feature can be depicted at a given scale

Front 50

What is accuracy?

Back 50

Is a combination of resolution, map scale, drafting skills, thickness of lines. Any number of factors can cause errors and the errors are cumulative

Front 51

what is framework data?

Back 51

framework data is the set of continuous and fully integrated geospatial data that provide context and reference information for the country.

Front 52

what is the purpose of framework data?

Back 52

improve everyones operation, reduce duplication and improve interoperability, reduce costs, facilitate new analysis, joint decision making.

Front 53

Where is the location of framework data?

Back 53

Framework data are distributed accross the country, sites are connected electronically, data may reside at each producers site, access may be passive or active.

Front 54

what is generalization?

Back 54

The process to reduce the complexity of the real world by strategically reducing ancillary and unecessary detail.

Front 55

what are the kinds of generalization tools?

Back 55

Dissolve, simplify line, eliminate, smooth line.

Front 56

What does eliminate do?

Back 56

Merges the selected polygons with neighboring polygons with the largest shared border or the largest area...eliminating trivial polygons

Front 57

what does simplify line or polygon do?

Back 57

simplifies a line or a polygon boundary by removing small fluctuations or extraneous bend from it while preserving its essential shape.

Front 58

What is aggregation?

Back 58

The process of collecting a set of similar, usually adjacent polygons to form a single larger entity.

Front 59

/what are the aggregation tools in GIS?

Back 59

Append and merge

Front 60

What is the modifiable area 1 unit problem?

Back 60

when the spatial units of a particular study were specified differently, we might observe very different patterns and relationships. Is an issue that arises when we use areal data

Front 61

what are all the different overlay techniques?

Back 61

erase, identity, intersect, spatial join, symmetrical differences, union, update.

Front 62

what are some types and sources of errors?

Back 62

1. Obvious sources: age of data and areal coverage, map scale and density of observations
2. varation and measurement: Positional error, attribute uncertainty, generalisation
3. processing errors: numerical computing errors, faulty topological analysis, interpolation errrors.

Front 63

Raster vs vector data model

Back 63

Raster
-location is referenced by a grid in a rectangular array (matrix)
- attribute is represented as a single value for that cell
images from remote sensing, scanned maps, elevation data
-best for continuous features:
elevation, temperature, soil type, land use

Hint 63

Vector data model:
-location referenced by x,y coordinates, which can be linked to form lines and polygons.
-attributes referenced through unique ID number to tables
-much data comes in this form
.SHP, MIF, GDB, DIME and TIGER
DLG from USGS for streams roads etcs
census data
-best for features with discrete boundaries:
property lines, political boundaries, transportation ect.

Front 64

What is the Raster model?

Back 64

Area is covered by grid cells. Location of each cell calculated from origin of grid -row and column number. Attributes are recorded by assigning each cell a single value based on the majority feature. Simple data structure: directly store each layer as a single table.

Front 65

What is arc-node topology? (vector)

Back 65

Defines relatios between points by specifying wich are connected to form arcs.defines relationships between arcs, by specifying which arcs are connected to form routes and networks.

Front 66

what is polygon-arc topology? (vector)

Back 66

defines polygons by specifying which arcs comprise their boundary

Front 67

what is left right topology (vector)?

Back 67

Defines relationships betwee polygons by defining from nodes and to nodes which permits left polygon and right polygon to be specified also left side and right side characterisitics

Front 68

What is the coverage file format of vector spatial data?

Back 68

It has multiple physical files in a folder. Proprietrary: no published specs and ArcInfo required for changes

Front 69

What is the shape file format of vector spatial data?

Back 69

Introduced with ArcView in 1993. Comprises several physical disk files (with extension of .shp, .shx, .dbf) all of which must be present. openly published specs so other vendors can create shape files.

Front 70

what is the geodatabase file format of vector spatial data?

Back 70

Native format for ArcGIS introduced in 2000. Multiple layers saved ina single .mdb (or .gdb) file. Proprietarty next generation spatial data file format

Front 71

What is the TIN data model?

Back 71

A TIN is a vector data structure which depicts geographic surfaces as contiguous non-overlapping triangles.

Front 72

How is the elevation of the terrain depicted by the tin data model?

Back 72

The vertices of each triangle match the elevation of the terrain exactly. This means that a topographic surface is representd by several triangles, each triangle face has an approximate slope, aspect and surface area

Front 73

What is a geodatabase?

Back 73

A physical store of geographic information inside a relational database management system

Front 74

What are the advantages of a geodatabase?

Back 74

centralized data storage, advanced feature geometry, and more accurate data entry and editing through the use of subtypes, attribute domains and validation rules.

Front 75

What are the basic and complex objects of a geodatabase?

Back 75

Basic: feature classes, feature datasets, nonspatial tables

Hint 75

complex: topology, relationship classes, geometric networks