Topic 04

Question 1

sources of geographic data

Answer 1

plethora of data available online

data is very expensive, use existing if possible

Question 2

aquiring geospatial data for GIS

Answer 2

remotely sensed data
survey data
field based data
geocoding text-based locations
digitizing maps
scanning and tracing maps

Question 3

primary data capture

Answer 3

direct measurement for a specific purpose or analysis for GIS

works for both raster and vector models

Question 4

Lidar

Answer 4

direct measurement for raster GIS

get points (x,y,z) as well as wavelength (colour)

Question 5

SFM

Answer 5

structure for motion

Question 6

two branhces of primary vector data capture

Answer 6

GNSS/GPS

Surveying

errors
2-5m on phone
1-2m error on mapping GPS
4c, error on survey grade

Question 7

what is GPS/GNSS

Answer 7

network of sateliites communicating with ground stations

sends out signals to locate devices on earth

provides a global system for calculating precise values’‘needs 3 but really 4 to be effectivee

Question 8

effernous

Answer 8

coorection to satellite from ground station

Question 9

differential GNSS operation

Answer 9

makes corrections in real time (2 receivers)

measuring angles and distances from other known points

receivers can collect information in real time

basis for ground based augmentation systems (GBAS)

Question 10

Satelittle based augmentation suystems (SBAS)

Answer 10

SBAS - satelittle based augmentation system

WAAS - wide area augmentation system

EGNOS - European geostationary navigation overlay service

Question 11

Ground surveyingq

Answer 11

3d location of any point determined iwth measuring angles and distances from other known points

increasingly becoming integrated with differential GPS

Question 12

secondary data capture

Answer 12

geographic data not designed specifically for GIS

repurposing previously collected data

can be raster or vector

Question 13

digitizing paper maps

Answer 13

paper maps hand traced

useful for historic maps

Question 14

scanning maps

Answer 14

converting hard copy mpas and other media to raster format for storage in a GIS

lots of errors subject to this

Question 15

scanning issues

Answer 15

scanned data products never tge same as original data

errors in the scanned map become errors inyour data base

Question 16

tracing and vectorization

Answer 16

convert maps into vector form

two methods

manual (digitizing), automatic (vectorization)

always left with some degree of error

ensure when digitizing that you are at correct scale and extent

Question 17

errors in digitilized data

Answer 17

slow, tedious work - prone to errors

allsorts of issues can be introduced

Question 18

types of digitilizing errors

Answer 18

positional errors and topological errors

Question 19

different types of errors in digitilizing

Answer 19

point (node) - not connecting, crossing over etc

line errors - undershoot, overshoot, missing node

polygon errors - not connecting

Question 20

reducing errors in digitlized data

Answer 20

fix immediatley

be aware of your data

Question 21

alignment errors

Answer 21

mismatches in adjacent spatial data
needs rubber sheeting to fix
mostly trial and error to fit

Question 22

secondary GIS data overview

Answer 22

existing data is cheaper and easier to get

two broad types, commercial and proprietary - made and sold for profit

open source - open and free to oublic

Question 23

proprietary data

Answer 23

data emobyding trade secretes and private information that is confidential

Question 24

commerical data

Answer 24

type of proprietary data developed and sold for proft

Question 25

data providers

Answer 25

big push in late 90s in America to release government data as publicly available (bill clinton) proprietary -> open source massive economic benefits goiv't transparency social benefits

Question 26

open data

Answer 26

freely accessed, used, reused, redistributed data

Question 27

public data

Answer 27

a form of open data that is crowd sourced by the public ex. OSM

Question 28

federal open data

Answer 28

natural resources biodiversity

Question 29

provinvial data

Answer 29

geodiscover AltaLIS

Question 30

Municipal data

Answer 30

City of Calgary open data catalogue

Question 31

SANDS

Answer 31

historic access - Calgary'

Question 32

distributing GIS data and metadata

Answer 32

data about your ddata geographic data is essentially useless if you don't have proper documentation about the data

Question 33

two types of metadata

Answer 33

object level (OLM) describes the contents of a single dataset collection level (CLM) describes the entire collections of geographic data

Question 34

OLM serves important needs

Answer 34

automates processes of search discoveries tells us info about the data

Question 35

Federal Geographic Data Committee (FDGC) elements

Answer 35

collection of standards for documentation ID information spatial organization data quality spatial references info entity and attribute information currentness distribution information citation information

Question 36

ArcCatalogue

Answer 36

collecting, viewing, adding metadata in ArcGUS

Question 37

who requires the most metadata information

Answer 37

experts and GIS analysts