gis last

Imagine you have Boolean rasters for 10 different criteria regarding the siting of a landfill. If you add the rasters together, what is the potential range of values in the output raster? What is the potential range of values if you multiply the rasters?

0 to 100 0 and 1

What determines the coordinate system of the output when overlay is used?

1. if the output is placed in a feature dataset, the CS matches the feature dataset 2. if the CS is et in environment settings, it will not become a part of feature dataset and will use environment setting CS 3. if environment settings is at default, output will match CS of forest input to the tool

approximately how long is a single Landsat orbit?

100 minutes

the landsat program started when?

1972

You have a geodatabase with 50 counties, 75 cities and 200 streams. How many feature classes are there? _______________________ How many features are there? __________________________ How many attribute tables are there? _________________________ How many total records are there in the attribute tables? ____________________

3 325 3 325

One second of latitude is approximately

30 meters

A "datum" is

A part of a GIS layer that includes the definition of a spheroid and a translation of this to the geoid locally or globally

An "ellipsoid" is

A simple mathematical model with a semi-major and a semi-minor axis

1. What primary characteristic distinguishes a spatial join from an attribute join?

A spatial join is similar to an attribute join, except that instead of using a common field to decide which rows in the table match, the locations of the spatial features are used. spatial join depends on : containment or proximity criterion also spatial joins create a new feature class, unlike attribute joins, which appends source attributes to destination table

How is the number 255 stored in ASCII different from storing it in binary form?

ASCII assigns an arbitrary values to store letters, numbers and symbols ASCII : (byte)(byte)(byte) binary : 11111101

Why should distance joins always be performed on layers with a projected coordinate system? What kind of projection should be used?

Because a geographic coordinate system uses units of decimal degrees, which cannot easily be converted into miles or kilometers, plus the result could be invalid because the geographic coordinate system uses spherical coordinates. In this case, it would be best to use a conic or azimuthal projection (e.g. UTM, State Plane, Equidistant Conic).

Define a Boolean raster. What values can it have?

Boolean raster is produced by map algebra and has values of (1) true or (0) false, indicating where some condition holds

what is a DOD?

DEM of difference

How can you determine the areas of polygons in a geodatabase? In a shapefile?

Geodatabased automatically create and update field containing the areas and perimeters of polygons or the lengths of lines shapefiles do not; you can create AREA or LENGTH fields for shape files to calculate values manually -must manually update these values following a clip, dissolve, intersection, or whatever (use calculate geometry)

What is geoprocessing? In what different ways can commands be executed?

Geoprocessing applies one or more functions in sequence to solve a problem or investigates properties of data sets.

describe the UTM system

It is a projected coordinate system with a "false easting" of 500,000 m

which instrument is used in BIBE to generate 3D topographic data for studying the geomorphology?

LiDAR

The TWDB water quality (destination) to well ID (source) has a cardinality of

Many to one

You are adding two rasters together in the Raster Calculator using the formula raster1 + raster2. Raster1 is in UTM projection, raster2 is in State Plane, and the geoprocessing Environment setting for the output coordinates is USA Equidistant Conic. By default, what coordinate system will the output raster have?

USA Equidistant Conic, the output raster will be given a coordinate system based on order of precedence : (1) CS set in environment settings (2) CS of first input tool

What is a buffer? Why is a dissolve often performed when buffering features?

a buffer is constructed to delineate areas that fall within a certain distance of a set of features buffers are features for each individual feature and may be very overlapping; so dissolving the buffer is useful to remove unnecessary boundaries

How does clip differ from "select by location"

a clip creates a copy of a feature class but only within the parameters of a selected polygon area select by location simply selects features in a feature class by defined spatial parameters but does not create a new copy

What is a "dangle" and how do you attempt to avoid them

a dangle is when a line fails to connect to another line or polygon snapping tools help avoid this

define datum

a datum includes a spheroid and its location relative to the earth's geoid it is used to reduce map errors introduced by differences between the spheroid and the earth's actual surface common datums in North America include NAD 1927, NAD 1983, and WGS 1984

What attribute fields will be present in a layer resulting from a dissolve?

a dissolve is used to group features together based on whether they share the same value of an attribute field when features are dissolved, the output layer is a new file contains the single attribute on which the dissolve was based; user can specify additional fields to summarize the information from the original features

What is the difference between a fractional and a graphic scale?

a fractional scale is not distorted if a map is printed or resized; a graphic scale will become distorted

Describe the difference between the terms grid and raster.

a grid is a format unique to ArcGIS, and other rasters, such as TIFF and JPEG files had to be converted to grid formats before they could be analyzed. A grid is a type of raster.

Describe the difference between a join and a relate.

a join appends fields from the "source table" onto the "destination table" a relate keeps tables separate but selected features from one table can cause features to be selected in the "related field" relates or joins must have a common field between two tables

define orthographic projection

a map projection in which locations on a sphere are projected onto a planar surface

define stenographic projection

a map projection in which locations on a sphere are projected onto a planar surface

define oblique projection

a map projection in which locations on a sphere are projected to a cylinder or cone of paper at an arbitrary angle

define transverse projection

a map projection in which spherical coordinates are converted to locations on a cylinder or cone tangent to a sphere along a line of longitude

define tangent projection

a map projection in which spherical coordinates are projected upon a surface that leis tangent to the sphere along one line of latitude

define secant projection

a map projection in which spheroidal coordinates are projected onto a surface that intersects the sphere along two great circles

NDVI is a vegetation index that is calculated from

a ratio of bands 4 and 4 (IR and R)

define features dataset

a set of feature classes in a geodatabase that share a common coordinate system and can participate in networks and topology

What is the difference between a "spheroid" and a "geoid"?

a spheroid is a spherical volume which can have unequal axes (semi-major & semi-minor = ellipsoid, type of spheroid) a geoid define geoid is the shape of the earth as defined by mean sea level and affected by topographic and gravitational factors the mean ocean surface of the earth, if the oceans were in equilibrium, at rest, and extended through the continents

if a projection definition includes two standard parallels, this means

a. It is a tangent projection b. It is a secant projection c. It is a cosine projection d. It is a transverse projection

Why is it usually advantageous to use a projected coordinate system when doing a map overlay?

area and distances is manipulated as a part of the fundamental nature of geoprocessing; always using a project coordinate systems gives some control to the inevitable distortion.

Describe the difference between and attribute and a standalone table.

attribute tables are linked to spatial data and standalone tables are not

define a feature class

basic type of vector data myst contain geometry and table

What function would you use to create a map of a study area such that all the features in the map stopped at the study area boundary?

clip tool

what changes geometry but does not change the attribute table fields?

clips and erases

the location (in wavelength) of the Landsat "bands" are selected to

collect data in the regions where there is a maximum atmospheric transmission

photogrammetry is a technique that uses overlapping photographs to

create maps with topography and orthoimagery

the buffer tool

creates a new polygon feature class at a fixed distance from other points, lines, or polygons

projection types

cylindrical conic azimuthal

What is "metadata"?

data about data

If you are recording your location from the screen of a gps into your field book, list the mandatory information that must be included in addition to the easting and the northing. (2 things)

datum, coordinate system

Alpine has a UTM easting of 630,000 mE. This means that it is east or west of the central meridian for the zone that it is in?

east

Give an example of a natural phenomena that would be rendered as a continuous raster.

elevation

Alpine has a UTM northing of 3,360,000 mN. We are this many meters north ofwhat feature on the earth?

equator

Arcmap is capable of supporting multiple layouts in one project (T/F).

false

Lines of longitude are referred to as "parallels" (T/F)

false

In the UTM system, what is the "false easting" and why is it used?

false eastings: an arbitrary x-coordinate translation applied to a map projection false northings: an arbitrary y-coordinate translation applied to a map projection usually to ensure that all values are positive

The acronym GIS refers to:

geographic information system

For each of the following attributes: single symbol, graduated color, or unique values map Precipitation Acres of corn per county Streams Land use

graduated color graduated color single symbol unique values map

Bart sent his *.mxd file to a friend. His friend responded that no map appeared when he opened the file in ArcMap. What is most likely the problem?

he may have sent the absolute path or the data that the map points to is not accessible to his friend

Give an example of "ordinal" data.

hurricane classification, 5,4,3,2,1,tropical storm

Give an example of when a fractional scale would be appropriate for a map.

if map is going to be printed and redistributed; fractional scale allows the map to be resized without scale being wrong

the Rio Grande Wild and Scenic river is located

in and downriver from BIBE

What happens if the two input layers in a join each have a field with the same name?

in the joined table, fields with identical names will be renamed in the output file so that all filed names are unique, NAME and NAME_1, usually source field is renamed

what changes geometry and also merges attribute tables?

intersection and unions

What is the difference between interval and ratio data?

interval data area measured on a regular scale ratio data are measured on a regular scale with a meaningful zero (unlike interval data) -0 kelvin has a significant 0, 0º C does not have a significant 0 both use graduated colors, graduated symbols, proportional symbol, dot density, or chart maps are used to map interval data

a map that covers a small area with a lot of detail is referred to as small scale or large scale?

large scale

If a polygon feature type is joined to a line layer, with the lines as the destination table, what will the feature type of the output layer be?

lines the output retains the features of the destination layer and appends the attribute information from the source layer the destination feature class determines the type of features in the output feature class

What does it mean to set "selectable layers"

makes only some layers selectable; restricts the data that can be selected from an interactive selection, select by attribute, or select by location

What is the cardinality for the following? Students to hometowns States to cities Counties to states

many to one one to many many to one

define projection

map projections are mathematical equations that convert degrees from a GCS into planar x-y coordinates of meters and feet so that the map may be portrayed on a flat sheet of paper all map projections introduce distortions of area, distance, direction, and shape

NDVI is calculated from

multispectral imagery

Describe why resampling should use the nearest neighbor method for geologic units and the bilinear method for elevation.

nearest neighbor resampling gives the new ell a value of the old cell that falls at or closest to the center of the new cell -good for discrete data bilinear resampling gives a distance-weighted average taken from the four nearest cell centers -good for continuous data

can interesting polygons only result in polygons?

no

for a shape file that has been produced via a map overlay process, will length or area fields always be accurate?

no

How many output fields will result if a summarized join is specified and a single statistic (e.g., Sum) is selected?

one field

cardinality of counties to groundwater wells

one-to-many

three main types of snapping

point, end, edge vertex

List the three geometry types that are referred to as "features" in vector based GIS data.

points, lines, polygons

List which tool (statistics, summarize, query) would work best Find all towns with more than 20,000 people Find out which subregion of the country has the most Hispanics Find the state in which Hispanics exceed the number of African Americans Determine the total damage caused by earthquakes in the United States Find the total number of volcanoes in each state

query summarize query statistics summarize

define raster

raster data employ arrays of values representing conditions on the ground within a square called a pixel the array is georeferenced to a ground location using a single x-y point a value raster such as DEM store a value representing an object or quality whereas a picture raster stores arbitrary color values within direct relation attribute raster contains 1 value indicating a single attribute; would need a new raster foe each attribute

Why is it best to store rasters in the same coordinate system in which you plan to use them?

raster data is normally stored in whatever projected coordinate system gives the bets and most undistorted view of the data many raster analysis functions incorporate distance and angle formulas that will give inaccurate results in GCS

Would raster or vector be a better format for storing soil types for Brewster county? Explain.

raster; good for representing features such as soil type because data can be categorized into color bins for easy representation in vector form, you'd have tons of adjacent polygons sharing all borders with another polygon because, while soil type is discrete, soil itself, on land, is pretty continuous

the dissolve tool

removes unwanted boundaries between polygons and unwanted line segments

List three map elements that can be added to a layout.

scale, north arrow, legend

four properties are distorted by map projections

shape, area, distance, direction

What are slivers? Explain how they can be prevented.

small extraneous polygons or lines that often theoretically shouldn't exist (sliver could be a discrepancy between a voting district polygon and a county polygon, for example) preventing by setting XY tolerance, specifies the minimum distance between vertices and will combine vertices that fall close together -lowers precision

Give an example of natural phenomena that would be rendered as a discrete raster

soil units

What is the most important difference between a spatial join and a map overlay?

spatial joins fail when spatial features to not overlap perfectly. Overlays allow you to break up a feature, like a road that crosses multiple land uses, you might want to have a segment of that road according to land use. spatial joins cannot split a feature like this. Overlays can= they create one-to-one relationships between features in the output table

What two options may be used to handle one-to-many relationships in a spatial join?

summarized joins are used to resolve one-to-many relationships the summarize function divides records into groups based on a categorical field in a summarized join, each feature in the destination layer is matched to many features in the source statistics are calculated for that group of features, and the results is appended to the feature record a one-to-many join can be summarized by containment (inside) or proximity (distance)

Describe the difference between thematic and image rasters

thematic rasters = not photographic imagery; can be continuous or discrete; used in symbology; often has restricted # of color bins which categorize the raster image raster= photography; pixels defined either has monochromatic (0-255) or RGB (0-255) + (0-255) + (0-255); colors often have normal distribution

What is the difference between a "central meridian" and the "Prime Meridian"?

they are both lines of longitude but a central median is just the central longitude of a map projection for which the x coordinate equals zero prime meridian is the arbitrary line in a GXS were longitude is defined as 0º

Which different types of outputs are possible (points, lines, polygons) when performing intersect and union?

union combines two polygon layers, keeping all areas and merging the attributes for both layers -creates all compossible polygons from the combination of features in two cologne layers intersect also merges the attributes but retains only the areas common to both layers, and may be preformed with points, lines, or polygons

define vector

vector data use sequences of x-y coordinates to store discrete point, line, or polygon features every feature is linked to an attribute table containing information about the feature

false "eastings" and "northings" are sometimes used so that

we don't have negative numbers in our coordinates

example of a dangle is

when two lines fail to connect

commutation of poerators refers to

whether a Boolean operation can be reversed and still produce the same result

List and describe the five Environment settings that can be helpful in managing raster analysis. When should these be checked and set?

workspace- sets input/output location for data output coordinates- sets desired CS of output data processing extent- preselects rectangular area of raster cells (extent) cell size- controls output resolution of raster mask- specifies polygon that controls which cells will be processed

do all the layers in a feature data set have to have the same coordinate system?

yes

Imagine that a parcels map is used as the zone layer for a zonal statistics function. Explain how the results would differ if the zone attribute used were (1) the parcel-ID number or (2) the land use designation.

zonal statistics function creates neighborhoods of data, not based on fixed size or shape but defined by another layer, called the zone layer. A zone is a region of a raster that shares the same attribute. the difference between these two is just zones based on parcel ID # or land use designation