Status: #📥/🟨 Tags: #archivedCards/geog150
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' GEOG 150 Week 6
Class:: GEOG150
Notes
GPS
? Global Positioning Systems
- technology that allows us to locate ourselves accurately on the surface of the earth
- know how the system operates to effectively use the data that is generated from it to allow the user to conduct spatial movements and explore objects
The main components are ? a receiver (user segment GPS a series of satellites (space segment) and ground control stations (base stations)
GPS finds location by ?
- calculating distance from other satellites, draws a ring at each satellite where they all intersect
- Sends a signal and times the travel time to find out distance
- Distance = Speed (light) x time
Receivers store time as ;; time + a (offset), making distance = speed x (5+a)
Factors to find location include;; latitude, longitude, altitude, and time
Spacial data comes from GPS, but there are other sources
Errors
Dilution of precision;; satellites are clustered
Propagation is when;; signal receiver is affected by atmosphere
Multipath error;; when signal takes a longer route due to reflection and interference
Ephemeris;; when orbit changes
Receiver noise;; Intereference on receivers, buy expensive equipment
Relativistic;; Time runs at different rate depending on relative speed between two observers, clock runs slower in space
Differential GPS
GIS Data Sources
GIS database purpose and method of connection ?
- store data from multiple sources
- linked together by identifier or common projected coordinate system
Data quality ? overall suitability of a dataset for a specific purpose
Completeness;;data must be spatially and temporally complete
Compatible;; multiple datasets used in the same project must be of the same format, scale, and extent
Consistent;; multiple datasets should undergo consistent methods of data capture, storage, manipulation and editing
Applicable;; data must be suitable for the analysis or project
Errors tell us about ? our confidence in what is known about the data
Discretization is ;; representing spatially continuous features using points, lines, polygons
Types of errors ? Boundary problems Overgeneralization
Accuracy;; measures how close our data is compared with reality
Precision;; level of detail in which we record data
Uncertainty;; confidence about what is not known
Metadata
? information about data, describes a specific data set
Meta stylesheets ? define the layout and style information about the data
Metadata is needed to ?
- Identify, exchange, manipulate, catalogue geospatial resources
Documenting data quality ? Location accuracy and precision (error between data and ground loc) Attribute accuracy and precision (how well are ground features represented?) Logical consistency (does the data follow normal rules of logic) Completeness (is the data complete or lacking in coverage?) Data currency (is the data up to date) Accessibility (readily accessible?)
GIS Data Input Sources
Scanning ? Create digital file from paper map, use a scanner (flat bed, drum roller)
Census data is useful for ;;social analysis in a GIS
Geospatial Revolution - Episode Two
Cities
- Used to tell when buses are
- Get data to make planning decisions
- LIDAR is when air craft gets terrain model
- Helps solve convenience for citizens (easy access to necessities, transit)
Package delivery
- Plans route
- Sees location of driver, seatbelt fastened, door opened, speed, stopping at a stop sign
- Plan new routes for package delivery
Healthy Supermarkets
- See the neglected/poorer areas that needed supermarket places
Thoughts/Questions
Created:: 2021-10-19 17:10