Data Quality Flashcards
what does attribute refer to?
what is there (realm of the forest specialist)
what does location refer to?
refers to the “where” of data
- xyz coordinates
- common to all mapping disciplines
absolute vs relative
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.
Resolution with raster vs vector
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.
what is the resolution determined by in satelite image?
can not go finer than satelite resolution.
What is important when making a small scale map?
- requires generalization
- results in positional inaccuracies
ex (pen width, 1mm. on a 1:20000 = 20m)
what does completeness refer to?
how much data has been collected for a given project
- private data unavailable
- public available through govt
- data may not be complete
Consistancy vs Compatibility
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.
What does applicability refer to?
- refers to appropriateness of data
- elevation and snowfree days vs elevation and income…
What does “nature of boundary” refer to?
- 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.
What are the errors in data capture sources?
Field survey (GPS is acurate to about 3m, errors in traverse, instrument error.)
how do you capture elevation in vector?
contours
spot heights
What does density of observations refer to?
- how often was data collected? spot heights for instance, did you get spot heights frome peaks and valleys?
- plots (sampling error)
Where can you get error in data encoding?
Paper map (original drafting errors)
Digitizing (hardware limitations, tracing “off line”)
what are some errors in data integration?
- raster - vector conversion
- sliver polygons (vector)
- edge matching and rubber sheeting
