Final Exam Flashcards

Question

What is a Boolean Operator?

Answer 1

In computer science, a Boolean is a logical data type that can have only the values true or false. Something either IS or IS NOT a (1 = yes / 0 = no)

Answer 2

A type of analysis in which geographic features (points, lines, polygons, or raster cells) are selected based on their distance from other features or cells.

Answer 3

The Raster Calculator lets you perform mathematical calculations using operators and functions, set up selection queries, or type in Map Algebra syntax. Inputs can be raster datasets or raster layers, coverages, shapefiles, tables, constants, and numbers.

Answer 4

A zone around a feature measured in units of distance or time. A buffer is useful for proximity analysis. Buffers can exist around Points/Lines/Polygons and can surround the feature, be on one side or the other. They can be rounded and can be dissolved or undissolved.

Answer 5

A buffer analysis can be performed. This is a determination zone around a geographic feature containing locations that are within a specified distance of that feature, the buffer zone, and how they interact with that buffer zone.

Answer 6

Dr. John Snow, England (1850’s) ▷ Using a map to demonstrate the spatial relationship between cholera cases and a particular water pump.

Answer 7

Geoprocessing tool that finds overlaps between layers ▷ Keeps attributes from all input layers ▷ Can also be used to check for overlaps within the same layer

Answer 8

Intersect keeps only those features that overlap ▷ Output type is based upon input layers ▷ If the inputs have different geometry types (that is, line on polygon, point on line, etc), the Output Feature Class geometry type will default to be the same as the Input Feature geometry type with the lowest dimension geometry. e.g. Where does caribou habitat intersect with heavy human use?

Answer 9

Total area of both objects. The Union tool creates a new coverage by overlaying two polygon coverages. The Output Coverage contains the combined polygons and attributes of both coverages. Only polygon coverages can be combined using Union. e.g. What area of parcels are within the floodplain zone?

Answer 10

Geoprocessing tool that removes any areas of overlap between input layers. Only locations in the input but not in the erase layer remain. e.g. buffer around drinking fountains in neighbourhoods (erase to find areas not with a certain range)

Answer 11

Long, skinny, irregular polygons, created when you perform an overlay (two different coastlines for instance), these polygons will throw off your results (adding to total area). You can get rid of them by merging them with adjacent polygons, also performing an erase by polygon size.

Answer 12

Maps played a role in colonization, they can control the land, divide it, controlled the naming of places. Many of these maps still control how we see the world.  “Decolonizing the map requires a recentering of indigenous geographical knowledge”  What can we do?  Reconsider how we classify our maps / include territorial acknowledgement / Pay attention to names / Step Back, indigenous-led mapping.  

Answer 13

``` Limited number of possible values ▷ Pixels with same value = same class ▷ Larger cell value does not mean more valuable ▷ Similar to polygons ▷ e.g. soil class, vegetation class, . ```

Answer 14

Unlimited number of possible cell values ▷ Larger cell value = higher value ▷ Same value does not mean it is in the same class – there are no classes ▷ Usually called a 'surface‘ ▷ e.g. elevation, precipitation

Answer 15

The primary benefit of compressing your data is to reduce the size of the file to help save disk space. This process groups like values together (counts numbers of cells and groups them)

Answer 16

Suitability Analysis Looks at multiple layers in order to solve a problem. (using a query, you rank locations and then come up with a best answer) This allows you to qualify, compare, and rank candidate sites based on how closely they adhere to criteria that you select and define.

Answer 17

The Euclidean distance describes each cell's relationship to a source or a set of sources based on the straight-line distance.

Answer 18

Nominal - Attributes are only names, forest vs rock   Ordinal - Attributes can be ordered, university rankings  Interval - Distance is meaningful, Temperature  Ratio - An Absolute zero exists (and is important to the measurement)

Answer 19

A "Multi Criteria Analysis" is a decision-making method that considers different factors. Suitability Analysis is an example of an MCE.

Answer 20

Replace the input cell values with new output cell values in order to: ▷ group values to simplify data (fewer categories), or ▷ reclassify values to a common range of values (aka scale)

Answer 21

When we are doing a suitability analysis we need a common range of values for all input datasets.

Answer 22

Best areas neighbourhoods for dog owners (Overlay of distance to Dog drinking fountains with percentage of dog owners gives us the best location to live)

Answer 23

(part map/part text) Generally geared towards non technical users, “they tell the story of a place, event, issue, trend, or patterning a geographic context”.

Answer 24

``` ▷ Text ▷ ArcGIS Online content ▷ Custom (simple) maps ▷ Videos ▷ Photos ▷ Spreadsheets ▷ Interactive use: ○ Queries ○ Popups - enables customized view and incorporates media ```

Answer 25

Basically another way to produce story maps.  KML (Keyhole Market Language) is an Image overlay (open source code) - we can do this with any image - save text as a .kml file to display in google earth.

Answer 26

Projection should be chosen based on: ○ Where you are ○ What you are showing (trying to preserve) (using appropriate projections) because they preserve a specific distortion (differences in areas you need to use a projection that preserves scale)

Answer 27

Scale must be included to give the map distance meaning. The map should not use a scale larger than the scale at which your data were collected.

Answer 28

It defines all the elements of the map and that they actually match the map!!

Answer 29

Good placement: 1) Easily visually associated with feature 2) Does not overlap other contents 3) Allows extent of feature to be seen 4) Reflects hierarchy of features

Answer 30

Using standard symbols help readability. | ▷ Example: railway lines are instantly identifiable

Answer 31

Can imply value: ○ Nominal data should use very different hues ○ Colour ramp for ranked data 24

Answer 32

Used for nominal data: classes rather than values. ▷ Example: Geology of Canada Chorochromatic maps are typically used to represent discrete fields, also known as categorical coverages. Chorochromatic maps differ from choropleth maps in that chorochromatic maps are mapped according to data-driven boundaries instead of trying to make the data fit within existing, sometimes arbitrary units such as political boundaries.

Answer 33

Choropleth ▷ Colour used to represent statistics ▷ Data must be normalized (not raw numbers) Choropleth - is a type of thematic map in which a set of pre-defined areas is coloured or patterned in proportion to a statistical variable that represents an aggregate summary of a geographic characteristic within each area, such as population density or per-capita income. Choropleth maps provide an easy way to visualize how a variable varies across a geographic area or show the level of variability within a region.

Answer 34

Map is often used where a point represents a particular quantity. ▷ Good for showing density ▷ Points are randomly generated

Answer 35

▷ Points used to show differences. ▷ Good for raw values ▷ Can be visually confusing (overlaps) and harder to read (difficult to gauge sizes)

Answer 36

Heat Map ▷ Raster representation of the density of point features. ▷ Best with continuous data. ▷ Good practice to display source data points with final product. ▷ Visually stimulating.

Answer 37

Lines which show movement between areas.

Answer 38

Area rescaled proportional to a variable. (skewed map where country visual size matches an attribute like population) ▷ Many different types ▷ Audience needs to be map-literate

Answer 39

We want our classes to do two things: 1. Maximize differences between classes 2. Minimize differences within classes Looking at the histogram will give you an idea of how best to achieve this.

Answer 40

4-6 classes.

Answer 41

Classes are based on natural groupings inherent in the data. Software identifies break points that group similar values: Minimize within group variance / Maximize between group variance.  Method is commonly used as it is good for data that are not evenly distributed on the histogram.  *it can be difficult to compare maps as the classes are custom to the data set*

Answer 42

The range of attribute values is classified into equal-sized subranges regardless of how the data are distributed. We specify the number of classes while software determines where breaks should be. (e.g. 0-10 / 10-20 / 20-30)

Answer 43

Each class contains an equal number of features. Good for emphasizing relative position - (i.e. top 20%). Because features are grouped by the number in each class, the resulting map can be misleading: similar features can be places in adjacent classes. Features with widely different values can be put in the same class *class breaks can be questionable.*

Answer 44

This classification scheme shows you how much a features attribute value varies from the mean. The GIS software calculates the mean and the standard deviation form the mean. Class breaks are then created using these values. *Best for normal distribution (Bell Curve)*

Answer 45

There is no reason why you can’t go in and “tweak” the classes. ▷ Sometimes you might need to come up with your own, or manually enter one that is not available in your software. e.g. Geometric Interval

Answer 46

Choropleth map using raw data, using too many classes (makes classes insignificant), Too many colours (hard to differentiate classes) .

Answer 47

Also known as relief, this is the third dimension (elevation) of land surface. The “lie of the land”. Expressed as elevation, slope, and aspect. It influences climate, weather, and water flow. Underwater terrain = bathymetry

Answer 48

Spatial interpolation is the procedure of estimating the values of properties at upsamples sites within the area covered by existing observations. Data collection and analysis is expensive and time consuming. Thus samples are spaced apart. Unknown data much be estimated from sampled data.

Answer 49

Digital Elevation Models - (DEM) is a raster grid with elevation values.

Answer 50

Digital terrain model (Terrain not included) - (DTM) Is a bare-earth elevation model.

Answer 51

Digital surface model (Terrain included) (DSM) Represents the earths surface and all objects on it, this includes environmental and artificial features (e.g. vegetation, buildings).

Answer 52

How accurately terrain can be modelled using DEM depends on the complexity of the terrain and the resolution of the raster. Choosing an appropriate resolution is important.

Answer 53

Triangulated Irregular Network (TIN) joins the elevation observation together with straight lines to create a mosaic of irregular triangles. Works best with terrain containing sharp features.  The triangles can represent terrain features:  Vertices: peaks, depressions, passes Edges: ridges, valleys

Answer 54

Measure of the steepness for your terrain.

Answer 55

The direction that your slope is facing.

Answer 56

The measure of the amount of changes in a landscape. (Measuring difference between cells). Terrain ruggedness Index (TRI) mean difference between a central pixel and its surrounding cells.

Answer 57

An effective way to project terrain (The angle of the sun on topography) used to mimic time of day/year. Helps to highlight terrain features (mountains, valleys, etc…)

Answer 58

Enhancing the size of terrain features on a map to make them more obvious. Always going to have this (especially with physical representations of terrain) or you would never register differences in height on maps/globe.

Answer 59

Measuring shape of the slope (concave/convex) Often used for hydrological modelling, especially with runoff and erosion.  Cell value: Upwardly concave + / Upwardly convex - / 0 indicates flat surface.

Answer 60

Essentially you just drape your 3D model with an image. Example: Combine a topographic map and 3D DEM. This provides a visually appealing relief map of the landscape. You can also generate several different terrain layers and use layer transparency, colour, and other design elements to create imaginative depictions of Earth's terrain in 2D or 3D.

Answer 61

Requires: ▷ Vector building footprints ▷ Height information: Digital Surface Model & Digital Terrain Model (bare earth) Subtract the DTM from the DSM to get building heights. Option to add texture/details

Answer 62

Similar to hill shading, you can move the source of illumination to simulate different times of day.  e.g. what shadows will be created by a proposed development.

Answer 63

A 360 degree view from a source point. ``` Red = not visible Green = visible ```

Answer 64

Developed in the 1970’s by the US military, Owned and operated by the US.  Full system of 24 satellites / “selective availability” downgraded signal in 1990s . Since then there have been continued improvements, currently millions of users (if not billions).

Answer 65

``` Global:  GPS, USA 1978  GLONASS, Russian 1982  BeiDou, China 2000 (operational 2018)  Galileo, EU 2011 ``` Local:  NavIC, India 2018 (standalone)  QZSS, Japan 2018 (enhancement for GPS to improve signal)

Answer 66

Satellite navigation systems are made up of 3 segments   “space” satellite; “user” w/ receiver; “control” fixed stations around the world

Answer 67

Distances are measured according to the time needed for radio signals transmitted by satellites (SPACE) to reach a receiver (USER). ▷ Distance = travel time x speed of light

Answer 68

(We need 4 satellites to perform this) The location is measured at the intersection point of the 4 spheres.

Answer 69

Errors can be (human made, selective availability to degrade signals, atmospheric interruption)  Multi-path errors  the signal may bounce off various obstructions before it reaches further receivers. Source of Error - GDOP  This is the result of satellite geometry, or the position of the satellites in relation to each other and the receivers. tirlateration.

Answer 70

Urban canyons are areas of interference due to surrounding structures, e.g. buildings, trees, land features which effect the satellites abilities to perform tirlateration.

Answer 71

Differential GPS uses fixed stations to increase the accuracy of GPS. (Differential GPS) is essentially a system to provide positional corrections to GPS signals. DGPS uses a fixed, known position to adjust real time GPS signals to eliminate pseudorange errors. 

Answer 72

The difference in accuracy depends on the set up. A cell phone with external GPS booster or tying into differential GPS will be able to have comparable results to a good GPS unit.

Answer 73

(Represents the timing of gps point drops) Important to note that standing still will continue to drop points (causing random patterns within your data).

Answer 74

Ensures limited issues in the field and a guide for the data collection. Pre planning, creating empty data sets, pre planning for issues, dry running the testing units (ensuring they are in working order) ensure its functionality and user experience.

Answer 75

(needed to fix attributes, spatial features) Post Processing is necessary because your data will need to be “cleaned up” when you are back from the field: Fix features, remove errors, add attribution.

Final Exam Flashcards

(99 cards)