GIS FINAL
What is the normalized difference vegetation index?
(NIR - RED)/ (RED+ NIR)
What are the four fundamental concepts of topology?
1. Connectivity 2. Containment 3. Adjacency 4. planarity
What is the accuracy of state plane?
1:10,000
How many nodes does each arc of a vector have?
2; a beginning and an end
How many satellites are needed for x and y positioning
3
What is the minimum number of ground control points for georeferencing?
3
What is the size (spatial dimension) of a USGS Digital Orthophoto Quarter Quadrangle (DOQQ)?
3.75 by 3.75 minutes
how many satelittes are required to knowx y z position
4
The visibible light portion of the elctromagnetic spectrum includes
420nm - 700nm
How many zones does CA have for the state plane and which projection does it use?
6zones; lambert conformal conic
What is a datum?
A mathematical reference for the surface of earth given as x y z coordinates
Describe the principle of containment:
A polygon is defined by closed and connected arcs
What is a reference ellipsoid?
An oblate sphere that is 1/219flatter at the poles
TRUE or FALSE: raster can have multiple values for each cell/pixel
BIG OLE FALSIE! For raster it is one to one
What are boolean expressions used for?
Boolean expressions are used to combine set alggebra conditions and create compound selections
VECTOR DATA SOURCES:
DLG, USGS contour lines US CENSUS Data SSURGO, NHD, TIN
What does the Universal Transverse Mercator "do"?
Divides the worls up into 60 zones 2 of which are in CA, spans from 84oN, Each zone is 6degrees wide, each zone has a northern and a southern hemisphere, yolo county is zone 10,
Describe how the intersect function works for spatial overlay;
EX: (A x B) means A intersect B, so the new layer will only be areas where a and b intersect where the x is read as "and"
How are locations "defined" i.e. what is the new lat vs long
Eastings/northings
How many levels of nested geogrpahy are there for census data and WHAT are they??
Eight - bc EIght is GREAT! We have Country, region, division, state, county, census tract, block group, census block (Sing to the tune of John Denver's "Coountry Road Take Me Home"
TRUE OR FALSE: the "AND" boolean operator is MORE inclusive
FALSE! It is exclusive!!! A point is only considered if it satisfies TWO requirements ___ AND ____
TRUE OR FALSE: A local operator applied to a raster cell will have variable size and shape
FALSE!!! Raster cells have uniform size, so using a local operator will have well defined, repeatable area
TRUE OR FALSE: neighborhood analysis are NOT affected by the shape of adjacent polygons
FALSE!!1 Very false. Using state polygons as an example, summary values such as population would be greatly influenced by adjacent states
true or false: orthogonal aerial photogrammetry is at an angle to earth of more than 3 degrees from the verticle
FALSEEEE: that would be the case if we were talking about oblique. Orthogonal is vertical
How are zones within the stateplane identified?
FIPS
true or false: for one feature only one attribute can be stored
FLASE!! One feature can have many, many attributes
List THREE reference ellipsoids:
GRS80 (geodedic reference system), Clarke, Bessel
What does GNSSstand for?
GlobalNavigation Satellitte syste
What type of neighborhood analysis or map algebra function does the following analysis entail? Calculation of the aspect from Digital Elevation Model (DEM).
I'm thinking focal
Which of the following interpolation methods is an exact interpolation method that constructs Thiessen polygons and assigns a value to an unsampled location that is equal to value observed at the closest sampled location?
IDW
What does a spheroid/ellipse do?
It defines the shape of earth with a semimajor/semiminor axis/flattening factor
How does the intersection operator work:
It returns value found in both tables as a joint table
How does the difference operator work?
It subtracts values found in the second table from values found in the first table
For map algebra, how does a zonal function work
It takes a set of values and applies a function to all the values for the output (whereas focal aka neighborhood will take many values to generate a single output cell
What is the purpose of a projected coordinate system?
It transfers coordinates of GCS from 3d to 2d
Describe how the union function works as spatial overlay:
It's taking one set of polygons and laying it over another layer and creating a new layer with the unique pieces from the polygons now intersecting.
What are the PCS units?
LINEAR --> feet or meters
What is set algebra:
Less than (<) Greater than (>) not equal to (<>)
How would each map algebra frame best be used?
Local, multiply inout by 2; focal, calculate slope from elevation; zonal, find the mean value; global, interpolate between points
A point constructed from the average x and y coordinates of all vertices and nodes making up a polygon feature is called the....
Median??
What colors can photogrammetry come in?
Natural colors, color infared, panchromatic (black and white)
In what part of the electromagnetic spectrum does green, healthy vegetation have the highest reflectance?
Near infrared (near IR)
When changing the cell size of a land use raster, what resampling technique do I recommend using for this type of raster?
Nearest neighbor
Which methods can we use for spatial interpolation?
Nearest neighbor,iDW,Kriging, Spline
Describe three common digitizing errors:
Over/undershooting a node and gettings crosses/gaps; switchbacks/knots/loops will disturb spatial analysis; snapping tolerance setting (lol) might not be sensitive enough, dangles (unclosed polygons), slivers, ggaps between adjacent polygons (can be avoided with snapping tools)
True or false: raster data is BIG and SLOW to load
Partially false: yes, raster data is big, but it is easy and quick to display
What are the eight primary operator using relational algebra?
Restrict, project, union, intersection, difference, product, join, and divide
What is photogrammetry?
Science of taking air photos from an airplane using films or digital cameras (analog vs.digital)
What are selection operators use for?
Selection operations identify features that meet one to several conditions or criteria. In these operations, attributes or geometry of features are checked against criteria, and those that satisfy the criteria are selected.
What does the project primary operation do?
Selects only desired columns anddisplays them
What is the sill of a semivariogram?
Semivariance at which leveling takes place; comprised of nugget and partialsill
The "census tract" level has complete geographic coverage based on which kind of "information"?
Short information
Broadly describe spatial analysis:
Spatial analysis is the process of using data from one or more layers to create new outputs
What is a map projection
Systematic transformation of x and y locations on the surface of a 3d sphere
True or false: every arc separates two polygons
TRUE
True or false: intersections are all at nodes
TRUE
true or falser:The topographic USGS 7.5 minute maps have a scale of 1:24,000.
TRUE
TRUE OR FALSE: several output layers can be generated from a single input layer
TRUE! For example, terrain analysis can take a raster grid of elevation and generate both slope and aspect layers
TRUE OR FALSE: lower levels of census groups can contain more detailed information, but lack full geographic coverage (depending on the variable)
TRUE! TRUE! TRUE!!!!!
True or false: vectors can have direction
TRUE! Think like vetors in physics "have both magnitude and direction"
True or false: outputs from spatial analysis can be both spatial or nonspatial
TRUE! You can get a new spatial layer or something nonspatial like a table
TRUE OR FALSE: A local operator applied to a vector polygon data set will have variable size and shape
TRUE!!! Unlike raster data set which have uniform sized cells, vector polygons come in all different shapes and sizes
TRUE or FALSE: the result of a union is at least as large as the largest table, but no larger than the sum of the two
TRUE!TRUE!TRUE!
True or false: Raster cell values can be continuous and index
TRUE: ratser cell values can be continuous and index
what is GDOP; Geometric/Position Dilution of Precision
The geometry of the satellites in orbit have a negative effect on positional measurement precision.
How does a secant projection work?
The globe cuts the map
What is tabular data?
The presentation of non-spatial data (i.e. attributes)
What is a false northing/easting
They are applied to the origin of y values to make sure all values are positive
TRUE OR FALSE: Most neighborhood operations are quite easy to program when using raster data models, and quite difficult when using vector data models.
This is true!
How is TIGER/LINE data linked to Census Bureau Demographic Data?
Tiger/Line data is linked to Census data via geographically encoded entitys
True or false: vectors are efficient accurate and good at depicting
True
GNSS includes which satelittes
US NAVSTAR, GLONASS (russian), EU Galilleo, China Beidou, IRNSS(indian)
List sources of raster data:
USGS 7.5 minute topo quads, USGS DEM, USGS DEM, USGS DOQ, USGS DOQQ, NAIPimagery (National Agriculture Imagery Program, NAIPimagery (National Agriculture Imagery Program, NASSdata (National Agricultural Statistics Service, LiDAR(Light Detection and Ranging, special case
How can the positional accuracy of a GPS be improved? (Select all that apply)
Use a differential GPS, take a long measurement at a location
What are the three major GPS segments?
User, Space, Control
How is attribute information entered in GIS?
Using a database management system; DBMS
What is a digital line graph:
Vector data source: vector files showing township & ranges, contour lines, rivers, lakes, roads, railroads and towns
What is the standard false color composite using NIR?
Veg is Red,Urban is Cyan, and soil is browns and water is black.Seems intuitive enough.
What is a geographic coordinate system?
Your own choice of potato model! it's the 3d model
define incident radiation:
amount of solar radiation energy received on a given surface during a given time
Conformal preserves
angle and shape
Describe the principle of adjacency:
arcs have left and right sides because every arc separates a polygon into two pieces
Equivalence refers to:
area think "equal area"
Projection types,list three:
azmuthal (planar), conical, cylindrical
What are the main GPS error sources?
clock errors, signal errors, interference in the atmosphere, satelitte position, geometrical error, intentional errors, human errors, reciever errors, obstruction
Describe how the identity operator works:
computes inter section of input features and identiy features
What are the units of a GCS
degrees/minutes/seconds
What is resection/trilateration?
determine position relative to satellite "reference points" using the geometry of triangles; The receiver figures out its distance to satellites using the travel time of radio signals. To measure travel time, GPS needs exact timing (clock) and exact satellite positionsH
What is the "range" of a semivariogram
distance at which the semivariance starts to level off (range of spatial autocorrelation), beyond range semivariance isconstant
Describe the concept of planarity:
features can only exist on a 2d plane, i.e. we don't have three dimensional polygons
A graticule shows what type of coordinate grid on a map?
geographic coordinates
What is a datum?
it is the GEODEDIC netowrk of reference locations that define anchoring points for the coordinate system
Boolean operators as spatial analyis: describe how the clip function works
it works like a cookie cutter! It takes a shape and lays that shape over the input layer and cuts out the polygons like a stamp
Geocoding is a spatial data analysis method that
locates addresses based on house numbers and street length.
Which types of cardinality correspond to relates?
one to many or many to many
Which "cardinal relationships" correspond to joins?
one to one or many (features) to one non-spatial recrod
What is a semivariogram and what does it do?
provides spatial autocorrection in a data set, can be used as an interpolator when fitted with a mathematical function
What is "cardinality"
relationship of one data table to another in database design (or equivalency between sets) This is the one to many versus many to one stuff
Raster grids can have what kind of values
resolution, extent, rows, and columns
What is the nugget in a seimvariogram?
semivariance at distance h = 0 (y-intercept); represents measurement error or microscale variation orboth
What are the types of photogrammetry?
single or overlapped
Which of the following are considered first derivatives of a Digital Elevation Model (DEM)?
slope, aspect, curvature, flow direction
What projection systems do state plane use?
transverse mercator and lambert conformal conic
A choropleth map is a good choice to show attributes from a point feature class.
true
When setting a ground control point (GCP) in the Georeferencing process, the source point should always be set on the dataset that needs to be georectified and the target point onto the dataset that has a coordinate system defined.
true
What is spline interpolation?
uses an interpolation method that estimates values using a mathematical function that minimizes overall surface curvature, resulting in a smooth surface that passes exactly through the input points.
Which is known for storing topology (arcs, nodes, and polygons): raster or verctor
vector
What is SSURGO?
vector data source: (Soil Survey Geographic Database),
What is NHD?
vector data source: Source of Vector Data: National Hydrography Dataset)
What is the UC Census data and how does it work:
vector data source: Tiger/line -Topologically Integrated Geographic Encoding and Referencing; point, line, and polygon features to represent streets, water bodies, railroads, administrative boundaries, and select landmarks),
What is TIN?
vector data source: Triangular Irregular Network, created from point elevation data and breaklines, TINsdisplay topography!)
What are USGS contour lines?
vector data source: lines of equal elevation, kind of like isobars in ATM,
