intro to GIS

Question 1

GIS software

Answer 1

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

Question 2

spatial features can be

Answer 2

discrete or continuous

Question 3

discrete spatial features

Answer 3

houses, roads, wells = vector

Question 4

continuous spatial features

Answer 4

rainfall, elevation = raster

Question 5

discrete geographic features are better represented by

Answer 5

georelational vector data model (points, lines and polygons)

Question 6

vector data rules

Answer 6

• 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)

Question 7

continuous geographic features are better represented by

Answer 7

raster data model or grids & cells

Question 8

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

Answer 8

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

Question 9

forms of raster data models

Answer 9

• aerial photographs (digital orthophoto quadrangle)
• satellite images

Question 10

remote sensing and GIS

Answer 10

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

Question 11

pixel values in a raster image

Answer 11

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

Question 12

colors are a proxy for the number values because

Answer 12

different land covers reflect different colors

Question 13

why vegetation reflects near infrared

Answer 13

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

Question 14

spatial analysis in GIS

Answer 14

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

Question 15

vector analysis with GIS using

Answer 15

buffers
overlays
-union
-clip
-intersection

Question 16

buffer

Answer 16

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

Question 17

overlay

Answer 17

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

Question 18

GIS analysis: buffer and overlay

Answer 18

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

Question 19

coordinate systems

Answer 19

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

Question 20

basic elements of a map

Answer 20

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

Question 21

raster analysis

Answer 21

map algebra
- zonal
-focal
-local
-incremental

Question 22

DEM-specific

Answer 22

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