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GIS Test 3
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Gravity
Terms in this set (157)
Which DEM algorithm is used in ArcGIS
Horn's
What software is used for 3D rendering
ArcScene
Can a TIN derived from a DEM be as accurate as the full DEM?
No!
An area surrounded by higher elevation values in a DEM
sink
When using Shreve, an intersection of 1st and 2nd order streams makes
3rd order
How do you fix relative error in a DEM
Filling the DEM
What two factors affect the accuracy of geometric transformations
distribution of points
number of control points
measure of quality of a geometric transformation
RMS error
what value is used to limit raster analysis from certain cells
NoData
what raster operation should be used to combine watershed boundaries
local
what si the primary source for creating a TIN
DEM
what is the number of pixels used in a cubic convolution
16
what makes raster faster
pyramiding
in raster analysis what is the output cell size set to
equal to or larger than the largest cell in the input
the only operational Landsat satellite
Landsat 8
what kind of model is the triangulated irregular model
elevation model
First multispectral photography from space
during the 1968 Apollo 9 mission
First space photography satellite
ERTS1
ERTS
earth resources technology satellite
ERTS1 date
July 23, 1972
later renamed Landsat1
Landsat 1's former name
ERTS1
Number of cameras on skylab
6
Only operational satellites
Landsat 7 and 8
(7 is compromised)
Landsat 7 date
April 15, 1999
Landsat 8 date
Feb 11, 2013
MSS
Multi spectral Scanner
TM
Thematic Mapper
MSS satellites
landsat 13
5 bands
TM satellites
landsat 4 and 5
(7 bands)
ETM
enhanced thematic mapper
ETM satellites
just landsat 7
OLI
operational land imager
OLI satellites
landsat 8
ll bands
What is the temporal resolution of landsat 8
16 days
landsat 9
set to launch in 2020
CBERS 12
china brazil earth resource satellite
CBERS 12 info
1999
MODIS
moderate resolution imaging spectroradiometer
MODIS band number
36
MODIS info
sensor onboard two NOAA satellites (terra/aqua)
used for cloud cover, surface temp, chlorophyll concentration, etc.
One of the most frequently used satellite data
MODIS
SPOT
systeme pour l'observation de la terre
SPOT info
french, sweedish, belgian satellite
1986
successors every 34 years
ASTER
Advanced Spaceborne Thermal Emission and Reflection Radiometer
ASTER info
cooperative effort between NASA and Japan's METI
japan's METI
ministry of economy trade and industry
Sentinel satellite number
6
Sentinel satellite agency
european space agency
Sentinel numbers
1. radar imaging
2. multipectral
3. Multi instrument, sea surface
4. Atmosphere
5. Atmosphere
6. Radar altimeter/oceanography
IKONOs
commercial satellite
1999
3 day revisit period
Quickbird
private satellite
2001
1 to 3.5 day revisit
Worldview 2
satellite sensor
sun synchronous
panchromatic (8 multispectral)
Raster data
DEM and DTM
DOQ (DOQQ)
DEM and DTM
USGS
SRTM
LiDAR based
DOQQ
Digital Orthophoto Quarter Quadrangle
DEM
digital elevation model
DEM definition
an array of uniformly spaced elevation data
USGS DEMS
7.5 minute DEM
30 minute DEM
1 degree DEM
alaska DEM
7.5 minute DEM
7.5 by 7.5 minute block that corresponds to USGS 1:24,000 scale quadrangle
SRTM
Shuttle Radar Topography Mission (DEM)
SRTM info
usgs offers SRTM dems
radar collected in feb 2000
better accuracy than 16m
LiDAR
Light Detection and Ranging
LiDAR info
aircraft mounted scanner
onboard GPS
makes high res DEMS
resolution of .5 to 2 meters
vertical accuracy of 15 centimeters
DOQQ
Digital Orthophoto Quarter Quad
DOQQ definition
a digitized image prepared from aerial photograph
DOQQ info
7.5 min quadrangle
removed distortion from camera tilt
geometric transformation
converting digitized map into projected coordinate system
geometric transformation alt definition
using a set of control points and transformation equations to register a digitized map/image onto a projected coordinate system
GCP
ground control point
GCP definition
points where both image and real world coordinates are identified as the same
raster transformation
uses polynomial, spline, adjust, projective, or similarity transformation
what kind of polynomial is used to shift the data
a zero order polynomial
1 link is enough
what kind of order is used to shift and/or rotate/scale a raster
first order
(3 link minimum)
high order transormations
require more links
RMS
root mean square error
RMS definition
measure fo the quality of a geometric transformation
displacement between actual and estimated
RMS process
taking root mean square sum of all the residuals
who defines the RMS tolerance value
the data producer
LANDSAT image RMS error tolerance value
<1 pixel
georeferencing toolbar
used to align raster data
spatial adjustment is used with
vector data
spatial adjustment
transform
rubbersheet
edge snap
transfer attributes
rubbersheeting
adjusting source layer to match accurate layer
preserving straight lines and stretching features
can adjust within limited areas or all features
resampling
filling each pixel of the new image with a value from (or derived from ) the original image
when do you need resampling
when there is a change of cell location or cell size between input raster and output
nearest neighbor method
new pixel value will be from nearest pixel from original
nominal or ordinal data
bilinear interpolation
averages 4 nearest pixel values
cubic convolution
averages 16 nearest pixel values
pyramiding
building different pyramid levels to represent reduced resolution rasters
pyramids make
RASTER FASTER
levels raster analysis can be performed at
cell elvel
group of cells
cells within entire raster
analysis environment
area of analysis and output cel size
can cell size be changed
YES
output cell size setting
equal to or larger than the largest cell size in the input
with a 10m and 30m input, wat is the output
30m
analysis mask
limits analysis to cells without "no data"
map algebra
manipulating raster layers with mathlike expressions
different map algebra operations
local
focal
zonal
global
local operations
aka cellbycell
new raster from single input raster
raster calculator
outputs raster as math function
local functions
work on single cells (one after another)
reclassifi
local operation that creates a new raster by classification
neighborhood operations
involves a focal cell and set of surrounding cells
common neighborhoods
square
circle
donut
wedge
zonal operations
work with two raster layers
one defines zone
global functions
output of each cell is a function of the entire grid
typical global functions
distance measures
flow directions
weighting measures
global operation distance
euclidean distance and cost distance
euclidean distance too
measures straightline distance from each cell to the closest source
mosaic raster operations
combine multiple input rasters into single raster
raster data extraction operation
creates new raster from existing raster
terrain analysis
used in a number of applications such as snow cover evaluation, soil mapping, landslide delineation, soil erosion etc
terrain mapping
can use both raster and vector data
two common stypes of data used in terrain analysis
raster based
DEM
vector based
TIN
DEM
digital elevation model
TIN
triangulated irregualr network
we can convert
TIN to DEM and DEM to TIN
TIN info
appximates land surface with nonoverlapping triangles
irregular/regular distribution of elevation points
DEM info
regular array of elevation points
used by most GIS users

USGS DEMs include
7.5 minute
30 minute
1 degree DEM
alaska DEM
SRTM
Shuttle Radar Topography Mission
two classes of level 1 error in a DEM
global
relative
global error
due to displacement of a DEM
can be corrected with transformation
relative error
local significan terror
relative to neighboring elevations
artificial peaks/sinks
fix by filling DEM data
slope
maximum rate of chance in value from each cell to its neighbors
output slope raster can be calculated with
percent slope or degree of slope
aspect
directional measure fo slope
starts at north with 0 and moves clockwise
algorithm used in ArcGIS
HOrn's algortihm
Factors that influence slope and aspect measurement
DEM
resolution
quality
Computing algorithms
Local topography
contour lines
connect points of equal elevation
contour interval
vertical distance betweer contour lines
base contour
from which contoruing starts
vertical profile
shows changes in elevation along a line
hill shade
shows how terrain looks with the interaction between sunlight and surface features
3d draping
makes perspective look more realistic
viewshed analysis
the process of deriving viewsheds
viewshed
portion of land surface that is visible from 1+ viewpoints
line of sight operation
basis of analysis in viewshed
sight line
connects point and target
hydrologic modeling
tools that let you
identify sinks
determine flow direction
calculate flow accumulation
delineate watershed
create stream networks
watershed
area that drains surface water to a common outlet
hydrological unit
includes watersheds
used for management
watershed delineation
using DEMS and raster data operations to derive topological features like stream networks
watershed delineation uses various
scales
delineation can be
area OR point based
sink
area surrounded by higher elevation values
aka depression or pit
water can flow in but not out
number fo sinks
higher for coarse resolution DEMS
not uncommon for
1% of cells in 30 meter resolution to be sinks
fill them
flow direction
raster showing direction water will flow out fo a cell (filled elevation raster)
determined by surrounding cells
can only flow into 1 cell
GIS model ASSUMES NO SINKS
flow accumulation
tabulates the number fo cells that will flow into a single cell
number of upstream cells contributing drainage
strean network
based on threshold accumulation value
high threshold
less dense streams
each section of the stream raster line
is assigned a unique value and is associated with flow direction
Strahler stream order
stream order increases only when two streams of the same order come together
Shreve stream order
all interior links in shreve model are additive
pointbased watershed
delineates watersehd for a point of interest
pour points/outlets
points of interest in a pointbased watershed
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