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FRST 328: GIS > Data Quality > Flashcards

Flashcards in Data Quality Deck (17)
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1
Q

what does attribute refer to?

A

what is there (realm of the forest specialist)

2
Q

what does location refer to?

A

refers to the “where” of data

  • xyz coordinates
  • common to all mapping disciplines
3
Q

absolute vs relative

A

absolute - position w.r.t datum,
relative - position relative to other features

relative is of greater concern because then features can be viewed with respect to their surroundings.

4
Q

Resolution with raster vs vector

A

resolution: the smallest thing mapped (pixel) if u have 100 x 100m pixel, you cant capture anything smaller.
Raster: Pixel resolution
Vector: MMU (minimum mapping unit = smallest area mapped)
-determined in data capture stage.

5
Q

what is the resolution determined by in satelite image?

A

can not go finer than satelite resolution.

6
Q

What is important when making a small scale map?

A
  • requires generalization
  • results in positional inaccuracies
    ex (pen width, 1mm. on a 1:20000 = 20m)
7
Q

what does completeness refer to?

A

how much data has been collected for a given project

  • private data unavailable
  • public available through govt
  • data may not be complete
8
Q

Consistancy vs Compatibility

A

consistancy: uniformity… collected edited and processed consistantly.
compatibility: relates to combining data sets. scale and consistancy are usually determining factors. ex. when combining two maps the best error is that of the map with the most error.

9
Q

What does applicability refer to?

A
  • refers to appropriateness of data

- elevation and snowfree days vs elevation and income…

10
Q

What does “nature of boundary” refer to?

A
  • distinct line (forest/field)
    or
  • gradual (change in forest tree size as you ascend a hill. Possible with raster) Vector can do it with spot heights and volume.
11
Q

What are the errors in data capture sources?

A

Field survey (GPS is acurate to about 3m, errors in traverse, instrument error.)

12
Q

how do you capture elevation in vector?

A

contours

spot heights

13
Q

What does density of observations refer to?

A
  • how often was data collected? spot heights for instance, did you get spot heights frome peaks and valleys?
  • plots (sampling error)
14
Q

Where can you get error in data encoding?

A

Paper map (original drafting errors)

Digitizing (hardware limitations, tracing “off line”)

15
Q

what are some errors in data integration?

A
  • raster - vector conversion
  • sliver polygons (vector)
  • edge matching and rubber sheeting
16
Q

Every time you do something in GIS, you are…

A

adding uncertainty

17
Q

What is error

A
  • broad term indicating level of uncertainty