GIS Exam 2

name 2 coarse resolution land sensors

AVHRR *since the 1970s) MODIS

Two main image types. pros and cons of both

Aerial:common relatively inexpensive easy to interpret small area coverage can be geometrically corrected Satellite images:large area coverage broader spectral range digital formats inexpensive for large areas geometrically accurate

Databases and tables in a GIS are generally organized in a multi-tiered structure to: ease data updates, manage simultaneous access, ease program modification, insulate users, all of the above

All of the Above

Where do we get digital data in the US?

Department of Agriculture (forest service, nat. resources conservation service), Department of Commerce (census bureau, natl oceanic and atmosphereic admn), Department of the Interior (US geologic service, natl park service, fish and wildlife service, bureau of land management), Independent Establishments and Government corporations (EPA)

Slivers in overlay are due to: features in one layer that are not present in another layer, differnt representations of the same boundary, resulting in gaps and overlaps, editing problems, none of the above

Different representations of the same boundary, resulting in gaps and overlaps

Aircraft tilt is the largest source of distortion by far for most aerial photographs. T or F

False

Terrain shaded surfaces do not depend on cell aspect. T or F

False

The National Landcover Datasets (NLCD) identify vegetation type to the plant species level. T or F

False

A dissolve function is used primarily to combine data in two different layers. t or f

False. It is used to combine features in the same layer

most satellite images are collected with film cameras, while most aerial images are taken with digital cameras. T or F

False. Terrain changes are

A friction surface that has an 1 unit travel cost for all cells is not the same thing as distance surface. T or F

False. it IS the same as a distance surface

Civilian satellites have trouble resolving features smaller than 3 meters (about 10 ft) across. T or F

False. they can see from 1 m to 50 cm

Name 3 high resolution sensing systems.

Ikonos, quickbird, spot

Ways to change amount of land covered when taking aerial photos

Increasing flying height reduces scale (objects get smaller, area covered by each photo increases) Increasing focal length increases scale (objects get larger, are covered decreases)

Name 3 Medium resolution sensing systems

Landsat Thematic Mapper (TM, ETM+) Multispectral Scanner (MSS) SPOT- coarse modes

Which of the following are NOT digital data available in a national program. National Hydrological Datasets (NHD), National Wetlands Inventory (NWI), National Infrastructure Datasets (NID), Census Data

National Infrastructure Datasets (NID)

A key is an item that allows you to uniquely identify a row in a table. T or F

True

A table in third normal form is by definition already in first and second normal form. T or F

True

Buffer functions produce data that are the same dimension or higher. T or F

True

If the moving window kernel is the same size over the entire raster data set, you will reduce the size of the output raster relative to the input raster every time you apply a moving window function. T or F

True

Map algebra often involves the combination of map layers through addition, subtraction, and other mathematical functions. T or F

True

Spatial scope is the extent of an operation, and may be categorized as local, neighborhood, or global. T or F

True

Tables must have key items with a common domain if they are to be joined. Tor F

True

The third order finite difference method uses information from more cells in a 3 x 3 kernel than the bi linear method for calculating slope. T or F

True

Viewsheds classify the world as visible or invisible from a location. T or F

True

items, variables, and attributes are synonyms. T or F

True

you can crate moving window functions for the mean, range, maximum, minimum, and majority functions. T or F

True

Note which are ture for contour lines. each show a given level of elevation, could also be called isolines, are usually at fixed intervals, may touch, all of the above, none of the above

all of the above

Which of the following are used to interpret aerial images? tone, texture, size, scale, brightness, all of the above, none of the above

all of the above

spatial data analysis

application of operations to coordinate and related attribute data. most often applied to solve a problem, identify high crime areas, generate a list of road segments that need repaving. typically involves using data from one or more layers to create output

Which of the following are FALSE for flow direction. flow direction is the direction water will flow from a cell, flow diretion is usually stored as an azimuth angle, flow direction is away from pits, flow direction is used to calculate watershed boundaries, none of the above, all of the above

flow direction is away from pits

Digital data aquisition is a three-step process. name them

identify obtain ingest

selection operations

identify features that meet one to several conditions or criteria

spatial operations or spatial functions

involve the manipulation or calculation of coordinates or attribute variables. can be applied sequentially to solve a problem. a chain is often specified with the output of each serving as the input of the next

remote sensing

measuring an abject from a distance. for is that means using photographic or satellite images to gather spatial data

A restrict operation has the effect on a table of: only reducing the number of rows, only reducing the number of columns, reducing the number of rows and columns, none of the above

only reducing the number of rows

what models of operations work best for raster vs vector

raster takes neighborhood operations best because consistent number of neighbors. In vector the neighbors polygons can be different sizes and cause changes in data. network operations are generally easier to apply in vector models

Normal forms are useful because they: improve the portability our database, increase access speeds, remove redundancies, all of the above

remove redundancies

binary classification

simplest form of classification. places objects into tow classes. a set of features is selected and assigned a value, and the complement of the set, all remaining features in the data layer, is assigned the different binary value.

classification

spatial data operation often used in conjunction with selection. also known as reclassification or recoding. it will categorize geographic objects based on a set of conditions. ex. 1 sq mile or larger = Large, 0.1 to 1 sq mile =Mid, 0.1 or less = Small. Often used at the end of a map making to show a map projection well for others to read easily.

containment

spatial selection operation that identifies all features that contain or surround a set of target features.

spatial scope

the extent or area of the input data that are used in determining the values at output locations. a way that spatial data operations may be characterized.

Slope is: the rise over the run, the run over rise, neither

the rise over the run

What is the domain of an item? the number of different values it takes in a table, the number of different values it can take in a table, the set of values it can take in a table, the number of ways it can be viewed in a table, none of the above

the set of values it cna take in a table

neighborhood operations

use data from both an input location plus nearby locations to etermine the output value. the extent and relative importance of values in the nearby region may vary, but the value at an output location is influenced by more than jut the value of data found at the corresponding input location

global operations

use data values from the entire input layer to determine each output value. the value at each location depends in part on the values at all input locations

Local operations

use only the data at one input location to determine the value at a corresponding output loctation. Attributes or values at adjacent location s are not used in the operation

set algebra

uses operations <,>,=,<>. they can be applied either alone or in combination to select features from a set

Fundamental variables

• Planimetric (x,y) location and dimensions • Topographic (z) location • Color (spectral reflectance) • Surface Temperature • Texture • Surface Roughness • Moisture Content • Vegetation Biomass

What are some of the common data sources?

•USGS Digital Raster Graphics (DRG) ((US geological survey)), universal transverse mercator projection • USGS Digital Line Graphs (DLG), usgs too, • NLCD - National Land Cover Datasets •USGS Digital Orthophoto Quadrangles (DOQ) • USFWS National Wetlands Inventory (NWI) • Digital Soil Data (National & State) • USGS Digital Elevation Models (DEMs) • USDOC Census/TIGER Files