intro to GIS Flashcards

1
Q

GIS software

A

ArcGIS
QGIS
GEOMEDIA- local gvts
Smallworld (GE)-used by utility companies

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2
Q

spatial features can be

A

discrete or continuous

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3
Q

discrete spatial features

A

houses, roads, wells = vector

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4
Q

continuous spatial features

A

rainfall, elevation = raster

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5
Q

discrete geographic features are better represented by

A

georelational vector data model (points, lines and polygons)

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6
Q

vector data rules

A
  • thematic object forms its own layer ( roads separated from railways)
    each layer can have only one type of feature ( can’t mix points with polygons)
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7
Q

continuous geographic features are better represented by

A

raster data model or grids & cells

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8
Q

an example of raster data model : the digital elevation model (DEM)

A

a digital terrain representation technique, where elevation values/topography are stored in raster cells
- useful for hydrological modeling

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9
Q

forms of raster data models

A
  • aerial photographs (digital orthophoto quadrangle)
  • satellite images
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10
Q

remote sensing and GIS

A

a form of ‘primary’ data collection
- can be used to collect information about objects on the ground using satellite or plane based sensors

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11
Q

pixel values in a raster image

A

valued between 0-255
0 - black
255- bright cell

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12
Q

colors are a proxy for the number values because

A

different land covers reflect different colors

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13
Q

why vegetation reflects near infrared

A

absorb red, green, and blue, to convert into food
infrared is all that’s left

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14
Q

spatial analysis in GIS

A

map projections
attribute data
cartography: making a map & choropleth maps

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15
Q

vector analysis with GIS using

A

buffers
overlays
-union
-clip
-intersection

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16
Q

buffer

A

polygon created by reclassification at a specified distance from point, line, area

17
Q

overlay

A

places one ‘theme’ (e.g. soils) over another e.g (parking lots) e.g. check for soils which will cause problems of drainage for proposed parking lot

18
Q

GIS analysis: buffer and overlay

A

buffers can be combined with polygon overlays in order to analyze spatial information
e.g. find all habitat areas of owls that are within 500 m of country roads

19
Q

coordinate systems

A

(x,y) coordinate systems for drawn through the centre of the projection create new reference (x,y) for places in the globe

20
Q

basic elements of a map

A

title, map features, legend, north arrow, scale bar, neat line

21
Q

raster analysis

A

map algebra
- zonal
-focal
-local
-incremental

22
Q

DEM-specific

A

-slope
-aspect
-cross-section
-inter-visibility
-hydrology