Data input

Question 1

How does satelite imaging work

Answer 1

• uses energy from sun
• interacts with earths surface
• travels to satellite sensor
• transmitted to receiving station

Question 2

Digital Capture (how do you input data into GIS)

Answer 2

-Keyboard Entry
attribute data - entered in tables
spatial data - rarely done
-Digitize User Link
data from paper or screen is digitized (traced) in a series of points
-Scan User Link
scan to generate raster image
georeference

Question 3

What is digitizing?

what are the two modes?

Answer 3

Converting paper to digital information.

• Point mode
• Stream mode

Question 4

What is an important part of digitizing with regards to data quality?
what is drafting assist?

Answer 4

Data must be perfect for accurate results

- Drafting assist is a computer assisted method of perfecting data

Question 5

What is an important feature of GIS data with regards to how data is displayed?

Answer 5

All data is displayed as a series of points. Even lines are just a series of points.

Question 6

What is scanning?

Answer 6

Computer “photocopying” of data to generate a raster image, vectorize the data (optional), and georeference it.

Question 7

What is an “artifact”?

Answer 7

an artifact is a data error that generates a spike or a loop in what should be a straight line.

Question 8

What are some user generated errors?

Answer 8

• poor tracing
• sliver polygons (overlapping polygons)
• under/overshoots (not quite matching node ex, road too short or long)
• missing or duplicate features (accidentally missing points or duplicating points when tracing.
• not updating database

Question 9

What is a major advantage of GIS over paper maps?

Answer 9

GIS has the ability to create overlays and compare data easily.

Question 10

What are 4 important things to remember when combining data (data transformations)?

Answer 10

• Convert to same projection
• Convert to same datum
• Edge matching adjacent maps
• Rubber sheeting

Question 11

What is rubber sheeting?

Answer 11

When maps are overlayed, incoming map is stretched to match base map. ( based on control points. )

Question 12

What generalizations are made in GIS to improve visual quality of maps?

Answer 12

• Line smoothing of roads and streams

- weeding coordinates ( reduce number of coordinates for a smaller database and faster operation )

Question 13

What is the purpose of a map?

Answer 13

• navigation
• communication (feature location, size, amount, pattern)
• used to conduct spatial analysis for decision making.

Question 14

What are the key points of cartographic design?

Answer 14

• Concept before compilation (purpose and audience)
• Hierarchy with harmony (exaggerate important information on map)
  critical map elements: figure
  background map data: ground
• Simplicity from sacrifice
  selection (how many map layers do you want to show?)
  simplification/aggregation
  only show relevant info
• Max info at minimal cost
  (5-7 classes max)
• Engage emotion

Question 15

What are important map making “Do’s” ? (6)

Answer 15

• use a few related colors
• use a few font types (vary size, boldness)
• use stronger colors for important features
• use subdued colors for background
• keep balance and symmetry
• clean and simple (avoid clutter and unnecessary detail)

Question 16

What is a cartogram?

Answer 16

spatial data is stretched to match the value of the target attribute for the map.

Question 17

Main difference between projections and datum?

Answer 17

Datum: uses an ellipsoid to reference the earths surface

Projection: transfer features from the globe onto flat maps (distorts data in different ways depending on the shape of the projection.)

Question 18

What are the GIS data sources?

Answer 18

-GIS Map Data
 Base maps (GeoBC Topo)
 Thematic maps    (forest cover, watershed etc)
-Remote Sensing 
 Lidar
 Satellite
 Orthophoto
-Field Surveys
 GPS
 Survey file (RoadEng)

Question 19

What does COGO stand for?

Answer 19

Coordinate Geometry (entering coordinates by hand)