Text 2 Flashcards
reproject
changing a dataset from one map projection(or measurment system) to another
spatial reference
the use of real world coordinate system for identifying locations
georeferencing
a process of alligning an unreferenced dataset with one that has spatial reference information
when data is _______, each location in that data is aligned with real-world coordinates
georeferenced
control points
point locations where the coordinates are known, used to align the unreferenced image to the source
If you cant use control points the only other way to georeference is by _______
field work
the minimum number of control points required to fit the unreferences image to the source is ____
three
when referenced data is transformed, its warped to make it match up with the source:
. can be _____,_______,_______, and/or _______
rotated
skewed-distorted or slanted
scaled
translated-shifting
affine transformation
turns _______ data into _______ _____ data
a linear mathematical process by which data can be altered to align with another data source
.calculates real world X and Y coordinates for each unreferences x and y coordinate
.is a first order transformation which is the type of transformation that is usually used for this
.unreferenced data will be turned into spatially referenced data
Root mean square error
an indicator of how well the now referenced data matches with the source
resampling
when you’re georeferencing an image, new locations for the image’s pixels will need to be calculated, and in some cases new values for the pixels will need to be generated as well
geographic information system
a computer based set of hardware and software used to capture, analyze, manipulate, and visualize geospatial information
.whenever examination, maipulation, or analysis of geospatial data is involved GIS is essential
.can link non-spatial data and link it directly to a location
GIS IS a computer based set of hardware and software used to ______, ______, ______, and ______ geospatial information
capture
analyze
manipulate
visulaize
geospatial information
something that has direct ties to a location on earths surface
GIS originated in 19__s through CGIS which was designed to provide large scale mapping of land use in canada
60
FATHER OF GIS
Roger Tomlinson
GIS: two ways of viewing the world
discrete-object view:
.a conceptualization of the world in which all relaity can be represented by a series of seperate objects
-each object has a fixed location, starting and stopping point, or boundary
. modelled in GIS as series of objects
.objects represented by points, lines, and polygons
continuous field view:
.not everything has a fixed boundary or is an object
.a conceptualization of the world in which all items vary across the earths surface as constant fields, and values are available at all location along the field
.vector data model are often not best way of prespessenting data so Raster data model used instead
Three vector objects:
explain each
ARE ZERO DIMENSIONAL OBJECTS,A SIMPLE SET OF COORDINATE LOCATIONS
are one-dimensional objects, created from connecting starting anf ending points(and any points in between that give the lines its shape)
are two dimensional objects that form an area from a set of lines(or having an area defined by a line forming a boundary
vector data model
a conceptualization of the world that representes spatial data as a series of vector objects
points,lines, polygons
Digitizing
the creation of vector objects through sketching or tracing representations from a map or image source
topology
how vector objects relate to each other (in terms of adjacency, connectivity, and containment) independently of the objects coordinates
adjacency-how one polygon relates to another polygon in that they share a common boundary
connectivity- how lines can intersect with one another
containment- how locations are situated within a polygon boundary
Raster data model
a way of representing spatial data that utilizes a series of equally spaced and sized grid cells, with each square cell representing the same area on earths surface
-each grid containing a single value representing data being modelled
Columns = _ axis
Rows= _ axis
x
y
attribute
the non-spatial data that can be associated with a spatial location
.can take 1 of 4 forms
- nominal
- ordinal
- interval
- ratio
Nominal Data
a type of data that is a unique identifier of some kind-if numerical, the differences between numbers are not significant
.ex: social security number/telephone number/names or descriptive data associated with a location
ordinal data
a type of data that refers solely to a ranking of some kind
.rankings themselves, not the numbers associated with the rankings
ex: place in a car race, 1st, 2nd, 3rd- not individual race time
Interval data
a type of numerical data in which the difference between numbers is significant, but there is no fixed non-arbitrary zero point associated with the data
.ex: temperatures
Ratio data
a type of numerical data in which the difference between numbers is significant, but there is a fixed non-arbitrary zero point associated with the data
.ex: persons age or weight
Attribute Table in vector and raster
Vector:
a spreadsheet-style form where the rows consist of individual objects and the columns are the attributes associated with those objects
.objects are stored as records(rows)
. information associated with records-attributes- is stored as fields(columns)
Raster:
. cant be handled in the same way as vector objects since a raster dataset is composed of multiple grid cells
. rather then having seperate records for each grid cell, rater data will often be set up in a table with each record featuring the value for a raster cell and an attribute showing the count of how many cells comprise the dataset
In an attribute table:
objects are stored as ____(____)
information associated with records-the attributes- is stored as _____(______)
records(rows)
fields(columns)
Join
a method of linking two(or more) tables together
- allows non spatial data to be connected to spatial locations
- linking tables info together
- this operation if managed by both tables having a field in common called a KEY
Key
the field that two tables have to have in common with each other for the tables to be joined
what is “the data about your data” called?
Metadata
- descriptive information about geospatial data
- coordinate system, projection, datum of data, when data was created, sources used, accuracy of data, etc.
____ is the key developer of “ARC” products
-initial product was _____ and has developed into _____
ESRI
Arc/info
ArcGIS
coverage
.IS BASED ON TOPOGRAPHY
a data layer represented by a group of files in a workspace cosisting of a directory structure filled with files and also associated files in an INFO directory
.
workspace
contains multiple coverages
shapefile
.IS NOT BASED ON TOPOGRAPHY
a series of files that make up one vector data layer
.can hold only one type of vector object thus there are point,line, and polygon shapefiles
geodatabase
a single item that can contain multiple layers, eash as its own feature class
.all geospatial information for a dataset
.object oriented structure is sep up so that multiple layers can be stored in a single geodatabase, each layers being its own FEATURE CLASS
feature class
a single data layers in a geodatabase
spatial analysis
examining the characterisitcs or features of spatial data, or how features spatially relate to one another
Dr. John Snow’s work on ______
CHOLERA
query
the conditions used to retrieve data from the database using an attribute table
Structured Query Language(SQL)
A formal setup for building queries
Relational operators are
=,,etc
compound query
a query that contains more than one operator
-make selections using multiple criteria
Boolean Operator:match
Intersection=
Negation=
Union=
exclusive or=
AND
NOT
OR
XOR
A simple type of analysis is the construction of a ______ around the elements of a data layer
define the blank
buffer-polygon of spatial proximity built around a features
Dissolve
the ability of GIS to combine polygons with the same features together
-boundaries between adjacent polygons that have same properties are removed, merging the polygons into a single, larger shape
Geoprocessing
the term that describes when an action is taken to a dataset that results in a new dataset being creates
-when on layer has some sort of action performed to it and the result is a new layer
Spatial Query
selecting records or objects from one layer based upon their spatial relationships with other layers(rather than using attributes)
overlay
the combining of two or more layers in GIS
.if one layer contains information about the locations of property boundaries an the second layer contains info about water resources, cobining these two in an overlay can help determine which resources are located on whose property
4 types of commonly used overlay
Intersect:AND
.retains the features that are common to two layers
Identity: NOT THE SAME AS “NOT”
.retains all features from the first layer along with the features it has in common with a second layer
-“NOT”=all features from the first layer, not any from second layer including whats in common
Symmetrical difference: XOR
.retains all features from both layers except for the features that they have in common
Union: OR
.combines all features from both layers
Raster Data spatial overlay:
Map Algebra:
.combining datasets together using simple mathematics
Site Suitibility:
.the determination of the “useful” or “nonuseful” locations based on a set of criteria
-what site is best
Suitability Index:
.a ssytem wherby locations are ranked according to how well they fit a set of criteria
In GIS _____-_____ evaluation can be used to weight and evaluate to determine suitability
multi-criteria
remote sensing
the process of collecting information related to the reflected or emmited electromagenetic energy from a target by a device a considerable distance away from that target from an aircraft or spacecraft
Nadir
the spot on the ground directly beneath the camera is reffered to as the nadir
panchromatic
only captures the visible portion of light in its entirety
-these photos will be grayscale
CIR Photo
Color infrared:
.a photo where infrared reflection is shown in shades of red, red reflection is shown in shades of green, green reflection is show in shades of blue
-blue reflection is not shown in the image as it is blocked by the filter and sisplayed as black
-health of areas of vegetation can be observed clearly
WATER ABSORBS EVERY COLOUR EXCEPT ______
BLUE
dEFINE:
- Principal Point
- Relief displacement
- Orthophotos
- Orthorectification
- the center point of an aeriel photo
- Relef displacement: tall objects tend to lean away from principal point to outward parts of photos
- an aeriel photo with uniform scale
.created by a process called orthorectification performed on a regular aeriel photo
4.. a process used on aeriel photos to remove effects of relief displacmeent and give image uniform scale
True Orthophoto
orthophoto where all objects look as if there being seen from directly above
Oblique photo
an aeriel photo taken from an angle-can see the sides of some buildings
Photogrammetry
is the process of obtaining measurments from aeriel photos
-figure out height, depth
records=
fields=
records(rows)
fields(columns)
