Week 6: S.1 Flashcards
What is spatial data?
The process where we locate the natural environment, transport, water resources, urban & rural development within a model space and assign positions to them. We can’t design a complex space without modelling it.
What do we confine space to?
Everything containing Earth and its atmosphere. Called the Geospace where in we collect geospatial data. Confine it to 3 dimensions.
What is geodesy?
The shape of the Earth and the definition of Earth datums.
What are map projections?
The transformation of a curved Earth to a flat map.
What is the difference between metric and non-metric spaces?
Metric: Assume space consists of an infinite set of points, located with coordinates. (Relationships between objects are derived)
Non-metric: Assume space consists of an infinite set of relationships between objects. (Objects related by relative descriptions: right, far, before)
What are the two types of data capture?
Primary (direct measurement) and Secondary (indirect derivation).
What are some methods of primary data capture?
Conventional survey. GNSS survey (GPS). Photogrammetry. Remote sensing.
What are some of the types of surveying?
Plane (small area).
Geodetic (shape of the Earth).
Topographic (maps).
Engineering (construction).
Cadastral (property boundaries).
Mining (surface and underground).
Hydrographic (seas and dams).
What kind of surveying is the following?
- Measurement of horizontal & vertical angles.
- Direct measurement of distances.
- Relies on a network of physical beacons to provide the geo-spatial coordinate system.
- Versatile & relatively low-cost.
- Extremely high precision (microns).
- Low data capture rates.
Conventional surveying (Also called plane surveying).
What kind of surveying is the following?
- Positioning from satellites.
GNSS surveying. (GPS)
What kind of surveying is the following?
- Mapping from aerial photos?
Photogrammetry.
What are some sources of secondary data capture?
Satellite images. Existing maps and plans. Geo-rectified aerial imagery. Google Earth.
What are the three types of errors you could make?
- Gross errors (Avoidable). Check your work!
- Systematic errors (Are corrected). Things like your formulas.
- Random errors (Unavoidable).
Any measurement is …….. of the true value.
Any measurement is an estimate of the true value.
What are the three factors to consider when taking a measurement?
Accuracy, precision and error.
Explain what accuracy and precision is?
Accuracy is how close the measurement is to the actual value.
Precision is how close the measurement is to other measurements of the same actual value.
