CP 4510 GIS Exam

Summary Statistics tool

- Calculates statistics from table attributes - the user chooses fields and statistics types - Creates a new table as its output

Two types of raster formats than can be analyzed in arcgis pro

.img and .tiff

Types of Projections

1. Cylindrical (preserve direction and shape) 2. Conic (preserve area and/or distance) 3. Azimuthal or planar (preserve area and/or distance)

Ways to classify numeric data

1. Natural Breaks 2. Equal Interval 3. Standard Deviation 4. Quantiles 5. Geometric Intervals

Types of Thematic Maps

1. Unique value 2. Graduated Colors (polygons) 3. Graduated Symbol (Points) 4. Dot Density 5. Chart Maps

4 differences in Vector vs. Raster Model

1. Vector is discrete/categorical data while Raster is continuous data 2. Vector is integer values while Raster is floats or ints. 3. Vector has only value per category and Raster has large range in values. 4. With raster it is unlikely to have same values as adjacent cells

all map projections have one or more of these 4 distortions

1. direction 2. shape 3. area 4. distance

Ellipsoids

Actual shape of the earth. smooth shape with slightly smaller n/s axis.

Geographic (unprojected) Coordinate System

Based on spherical coordinates. Measured in degrees of lat and long

works like a cookie cutter to extract features that lie inside the boundary of another data set.

Clip

Merging

Combines all features from 2 or more data sets into single feature class.

Projected Coordinate System

Converts spherical coordinates to planar coordinates. Uses set of mathematical equations and projects 3d coordinates to 2d map.

DEM acronym

Digital Elevation Model

Projections all distort one or more properties of: ____, ____, _____, and ______.

Direction, shape, area, and distance.

Discrete vs Continuous Map Data

Discrete: objects exist in defined location (Point, lines, polygons) Continuous: Data exist everywhere (raster)

Defined or Equal Interval

Equal Sized classes. User chooses class range for defined interval map or number of classes for equal interval map.

Works like a cookie cutter to extract features that lie outside the boundary

Erase

Buffers are temporary delineations of an area within a specified distance of a set of features. They do not result in the creation of a new layer.

False

Spatial queries can select partial features (E.g the portion of a river that falls inside a given county)

False

T/F: Streaming data or GIS web services are datasets stored on your local computer

False

T/F: Tabular Joins are permanent

False

T/F: The vector model is best for continuous data. The raster model is best for discrete data.

False

T/F: UTM coordinate system breaks the world up into 6 zones of 60 degrees each

False, 60 zones of 6 degrees each.

A geoid shifts the ellipsoid relative to the datum to achieve a best fit between the two.

False, A datum shifts the ellipsoid relative to the geoid to achieve a best fit between the two.

T/F: data or numeric classification applies only to vector data

False, applies to vector and raster.

T/F: In a many to one join, one record in the target or destination table matches many records in the join or source table.

False, one record in join table matches many records in target or destination

T/F: there are 5 basic field types for a table.

False, there are 6.

T/F: The raster model stores features as map objects called points, lines, and polygons.

False, this is the vector model. Raster model breaks map area into small cells calls pixels.

a _______ is a homogenous collection of features with a common spatial representation and set of attributes stored in a database table. for example a line ______ representing road centerlines.

Feature class, feature class

Categorical Data

Features belong to categories (rock type, volcano type, etc.). Portrayed with unique values map, and categories can be numeric or text.

Natural Breaks

Jenks Optimization method and exploits natural gaps in data. Good for skewed data

Importing or Exporting

Makes a copy of a data set and may include changing the format of the data model. Both done using feature class to feature class tool

Assuming target table is on the left, states to cities is an example of which type of cardinality.

Many to 1

MAUP

Modifiable Area Unit Problem: maps reflect the influence rather than data being mapped

MAUP stands for:

Modifiable Areal Unit Problem

Common Geograhpic Coordinate System for US

NAD 1983

Which resampling method should be used on categorical data?

Nearest neighbor

In an attribute table, dividing each value by the total of all the values is another way to _______ data.

Normalize

Common Projected Coordinate System for US

North American Equisdistant Conic

Interval Data

Places values along a regular numeric scale (elevation). can have negative values. Examples are temperature, population change

Ratio Data

Places values along regular scale with meaningful zero point and no negative values. Population of state capitals

What type of coordinate system are rasters usually stored in?

Projected coordinate system that preserves area or distance.

Which methods are used to extract or subset data from a dataset?

Queries, manual selection, and clip

3 types of Extracting Data

Queries: expression based on attribute field Clip: extracts features within a bounding polygon from another feature class Erase: extracts the features outside of a bounding polygon from another feature class.

Map Scale

Ratio of distance on map to distance on the ground. Dimensionless. 1 cm on map= 100,000 cm on ground

Rows are called?

Records

Two types of vector data formats are _____ and _______

Shapefiles and geodatabases

Match data type with map type: Nominal: Categorical: Numeric:

Single Symbol Unique Values Graduated Symbols

Common Projected Coordinate System for local areas

State Plane and UTM's

Data rasters

Store values representing measurements or categories and can be analyzed (ex: elevation, aerial imagery, land use, roads

SQL acronym

Structured Query Language

Shape_area and shape_length fields are not auto recalculated for geodatabase feature classes after processing.

T/F: False

Geographic Coordinate Systems are based on spherical coordinates and measured in latitude and longitude.

True

T/F: Boolean Operators are used when multiple conditions must be tested.

True

T/F: Quantile classification puts the same number of features into each class.

True

T/F: Shapefiles consist of more than one file.

True

T/F: Logistical Consistency assesses how well data represents real-world relationships.

True, for example: do roads connect at intersections?

T/F: Thematic accuracy is not related to data location

True, thematic accuracy is related to accuracy of the attributes. Geometric accuracy is related to a feature's location.

Ordinal Data

Type of categorical data: Ranks categories using along a scale and uses a unique values map

Common Geographic Coordinate System for World

WGS 1984

When GIS servers provide data over the internet (streaming data), this is an example of a?

Web Service

Feature Dataset

a collection of feature classes in a geodatabase that share the same coordinate system and area extent

Vector model

best for discrete data. features are stored map objects (points, lines, polygons) 1 to 1 relationship between feature and row in table

Calculate field tool

can be used to enter an expression to calculate new values for a field in a table. can use existing fields in the expression.

Standard Deviation

compares values close to and far from the mean. (<0.5 std dev or 0.5-1.0 std devs)

3 types of projections are Azimuthal, ____, and ______.

conic and cylindrical

completely contains

contains but doesn't permit a shared boundary

Define Projection Tool vs Project Tool

define projection: 1. creates or changes only the CS Label 2. does not change coordinates in the file 3. Keeps original data set 4. use only when CS is missing or incorrect Project: 1. Changes coordinates in the file 2. Changes the label 3. Creates new data set 4. Use when changing a CS permanently. 5. used to assemble collections of data with the same stored CS.

target tables is known as

destination table and receives the additional information

Geocoding

displays addresses on a map by matching postal data fields in a table to a street data set

Normalizing by Field Percentage

dividing each value by the total of all values. (Number of congressional districts in each state by total # of districts to get percentage of congress in each state)

attribute query

expression is used to find records with values meeting a specific condition (counties with more than 100000 people)

A _____ can be a point, line, or polygon and represent a vector object or location on a map.

feature

What corresponds to a shapefile?

feature class

A ______ stores feature classes that have the same coordinate system and the same spatial extent

feature group

Columns are called?

fields

A ______ is the native data structure for ArcGIS and is the primary data format used for editing and data management

geodatabase

Raster Model

geographic space quantized into uniformly sized discrete units called pixels. Each pixel contains a numeric value that can be an int or float.

Feature Class

homogeneous collections of common features, each having the same spatial representation, such as points, lines, or polygons, and a common set of attribute columns

3 basic operators that test spatial relationships

intersect, contains, and proximity

one to many joins

many records in join table match one record in the target table, use a relate here in which the tables are linked together but remain separate. (congressional districts to states)

projection

mathematical conversion of points on the earth's surface to flat plane (map)

many to many

multiple records in one table can link to multiple records in another table. (each student takes many classes and each class has many students)

Geometrical Interval

multiplies each class range by a constant, best for visualizing strongly skewed or log increasing data like population density

Nominal Data

names or uniquely identifies objects. (Country Names, capital cities, rivers, water bodies). usually portrayed on single symbol map

Many to 1 joins

one record in the join table matches many records in the target table. (Joining states to congressional districts)

1 to 1 join

one record in the join table matches one record in the target table. (joining married to counties using FIPS)

Geodatabases

recommended model for storing spatial information for ArcGIS. containing many types of data (feature classes, rasters, tables)

Rasters always take the shape of a

rectangle

intersect operator

relational set operator that yields only the rows that appear in both tables, tests whether feature touch

Dissolving

removes boundaries of features with the same value in the specified attribute fields.

Quantile

same number of features in each class (Linear data distribution)

spatial query

selecting records or objects from one layer based upon their spatial relationships with other layers (rather than using attributes) (cities within 50 miles of earthquake)

6 field data types

short (2 byte binary) long(10 byte binary) float double float text date

standalone tables

simply store tabular data from any source.

join table is known as

source table and provides the additional information

Picture rasters

store color values (like taking a picture of a map) and cannot be analyzed (ex: scanned topo map, basemap)

Attribute tables

store data associated with a spatial feature class.

Geoid

surface modeled from gravity differences and is closest to true shape but too complicated for mapping.

example of target and source layer: map with counties that contain volcanoes

target = counties source= volcanoes

Contains/within

tests whether a feature is inside another

proximity

tests whether features are within a specified distance of another

source layer

the one containing the features being compared to

target layer

the one from which the features will be selected

Interactive query

the user visually identifies the desired features in a map or records in a table (states west of the mississippi)

Datum

to minimize discrepancy between geoid and ellipsoid these are used. datum shifts the ellipsoid relative to the geoid to achieve best fit. a geocentric or world centered datum optimizes fit for entire earth.

Shapefiles

vector feature classes developed for the early version of ArcView and have been carried over into ArcGIS. Stored in spaghetti data format. Appear as one file in Catalog but are composed of many.

raster resolution

x and y dimensions of each pixel, the precision is limited by this too. Increasing this increase storage requirements.

Are rasters always rectangular

yes