GIS week 3 Flashcards
(33 cards)
What is the difference between spatial data capture and transfer?
Capture generates new spatial data; transfer imports existing data into GIS.
What are five common techniques for vector data capture?
Keyboard entry, digitising, field surveying, photogrammetry, and LiDAR.
When is keyboard entry used for vector data capture?
For a small number of point features, manually entering coordinates into a table.
What is digitising in GIS?
Tracing geographical features from a map or image to create vector data.
What are the key steps in on-screen digitising?
Scanning, georeferencing, tracing, editing features, and adding attribute data.
What is digitising used for in GIS?
Creating vector data by tracing boundaries of geographic features.
How does field surveying capture spatial data?
By taking direct measurements in the field using instruments like total stations and GNSS.
What is a total station and how is it used in surveying?
A device combining electronic distance measurement and angular measurement to collect precise spatial data.
What is the purpose of a Global Navigation Satellite System (GNSS) in spatial data capture?
It enables accurate position measurement anywhere on Earth using satellite signals.
What are the three main operational GNSS constellations?
GPS, GLONASS, and Galileo.
How does a smartphone GNSS receiver collect spatial data?
It provides (x, y, z) coordinates using satellite signals via a mobile device.
What is C/N0 in smartphone GNSS, and why is it important?
The signal-to-noise ratio, which measures the quality of satellite signals received.
How does photogrammetry capture spatial data?
By measuring (x, y, z) coordinates from overlapping aerial photographs.
What does LiDAR do in spatial data capture?
It collects dense (x, y, z) point clouds using laser scanning technology.
What are the four main types of raster data from remote sensing?
Visible, infrared, multispectral, and hyperspectral imagery.
What is crowdsourcing in GIS data collection?
Gathering spatial data from the public using web, geotagging, and mobile devices.
What is spatial data transfer in GIS?
Importing and converting existing spatial data from external sources
What are some common digital spatial data formats?
GIS, raster, database, 3D, XML, and point cloud (LiDAR) formats.
What is the Feature Manipulation Engine (FME) in ArcGIS Pro?
A tool for spatial data transfer supporting over 300 data formats.
What are examples of spatial data transformations?
Raster-vector conversion, rubber sheeting, line simplification, and edge matching.
What happens during data structure conversion in GIS?
Converting between raster and vector formats, with potential information loss.
What is rubber sheeting in spatial adjustment?
A geometric transformation used to correct spatial distortions.
What does affine transformation do in spatial adjustment?
Scales, skews, rotates, and translates spatial data without altering angles.
What is line simplification (weeding) in GIS?
Removing redundant points to simplify a line or polygon while preserving shape.
