Spatial analysisA

• Geographic Information Science
• Lecture 2: Spatial Data
• Dr. Qing PEI
• The Department of Land Surveying and Geo-Informatics
• The Department of Chinese History and Culture
• The Hong Kong Polytechnic University

  
• Vector data


  • Lines representing roads in the Boston area
• Raster data


  • Scanned, historic map of the Manitoba

  
• Know about the location information
• It could be, see the next slide.
• Spatial data


  • When an image is georeferenced to a map or has embedded coordinate data
• Data can be transferred, flexible
• Spatial data


  • Contains addresses, which can be geocoded
• No, there is no information you could use to map this data. If the location of each school was listed, it would be tabular spatial data.
• Spatial data


  • It doesn't use the same coordinate system as data that is plotted on the earth, but you could map items on this brain. This scan is raster data since it uses pixels.
• Spatial data


  Information about the locations and shapes of geographic features and the relationships between them, usually stored as coordinates and topology
• Spatial data is all around us, especially because of social media and GPS enabled devices. It's not just in the form of paper maps now.
• Spatial data can come in many different formats and file types.
• Many types of software and programming languages can be used to view and analyse spatial data
• Spatial data presentation
• Software for Viewing Spatial Data


  • GIS Software (ArcGIS, QGIS)
  • Online Mapping Software (ArcGIS Online, CartoDB, Mapbox)
  • Statistical/Data Visualization Software (Tableau, R, MatLab)
  • Programming Languages (Python, Javascript (D3, leaflet), R, MatLab)
• Data Acquisition
• Data Capture for GIS


  • Digitizing in vector format
  • Scanning in raster format
  • Data conversion from other sources
  • Field surveys
  • Remote sensing
  • Laser scanning
  • Photogrammetry
  • GPS
  • Attribute information input
• Horizontal field survey methods


  • Traverse
  • Triangulation
  • Trilateration
• Vertical field survey methods


  • Leveling
• Total Station
• Remote Sensing captures the remote sensing image from the space by satellite, from air by aircraft or UAV
• Remote Sensing collects thematic data (what the object is) and positional data (where the object is located)
• Photogrammetry uses aerial photographs and techniques for making accurate measurements from them, to provide data on topography (ground surface elevations) used for input to GIS
• LiDAR = Light Detection and Ranging, uses a pulse of LASER light emitted, with return time and intensity measured, converted into 3D coordinates
• GPS provides users with positioning, navigation, and timing (PNT) services, with three segments: the space segment, the control segment, and the user segment
• A point cloud is a set of data points (X, Y, Z) in space, which may represent a 3D shape or object
• A mesh model is a collection of vertices, edges and faces that defines the shape of a polyhedral object
• Building information modeling (BIM) describes the process of specifying, creating, and managing digital information about a built asset such as a building, bridge, highway or tunnel
• Map Coordinates or Addresses


  1. Geocode Addresses

  2. Add XY data
• Collect Your Own Data
• GIS projects tend to generate many files, which are generally large in size
• Data Management Tips for file naming


  • Use file names that represent the file
  • Some software programs and tools may have file name constraints
  • Backup Your Data!
• Keep detailed notes about data sources, licensing constraints, data processing, what is stored where, and descriptions of the files you create and use
• The GIS project maintains links to the individual data files (the data is not embedded in the map document itself)