Obtaining data for GISystems is an expensive and typically complex task. Standards need to be defined (e.g., data quality, data validation, minimum mapping units), processes identified, and more, all operating within the mandate of the agency collecting the data, or requesting the data. One of the more important data collection frameworks involves the use of remote sensing. In this lecture I will briefly review some of the overall elements of data collection, and then more specifically review remote sensing.
Remote sensing was commercialized long before GIS became a mainstream technology, but it took over 30 years–when the two technologies joined forces–before remote sensing truly took off. GISystems require volumes of data, and data quickly becomes out-of-date. Thus, remote sensing has provided to GIS a means of acquiring up-to-date data for large geographic regions at relatively low cost (and GIS has provided the incentive to acquire up-to-date imagery). In particular, when working in fields such as resource management, regional planning, oceanography, disaster management and, increasingly, urban development, you will find that remotely sensed data is a ‘core’ dataset. Thus, a GIS analyst should have a fundamental understanding of remote sensing, given the synergies possible between the two fields.
Learning Objectives
- Understand primary data capture techniques: remote sensing and surveying;
- Recognize the four resolutions of remote sensors;
- Be familiar with the existence of secondary data capture techniques, such as scanning, manual digitizing, vectorization, and photogrammetry;
- Understand sources of digital geographic data and geographic data formats.
Required Readings
Text: Chapter 8: Data Collection in our main text, GI Science & Systems.
Slides for the data collection lecture.
Alternative text: Nothing specific to the topic.
Recommended Readings
An Introduction to Remote Sensing from PhysicalGeography.net provides a brief overview.
American Museum of Natural History: Biodiversity Informatics - The AMNH site has some very insightful interactive tools and overall discussions on the use of remote sensing (especially for land classification) and we recommend you review its content.
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Useful Resources
Some examples of GIS data collection standards: BC GPS data collection guidelines; RISC home page.
There are many sites that offer tutorials on the subject of remote sensing. Some of the main ones include:
- NASA Landsat Science - NASA has produced useful materials at the Goddard Space Flight Center that cover most of the fundamental concepts involved in satellite image interpretation and analysis (it contains some fairly technical details that you can skip over)
- Natural Resources Canada : Tutorial: Fundamentals of Remote Sensing
- ESA Eduspace A set of comprehensive resources is provided on the EDUSpace site developed by the European Space Agency (ESA)
- Measuring Vegetation (A description of NDVI & EVI)
There are many sites that allow you to view / download satellite data:
- USGS: LandsatLook Viewer
- Another USGS site for free satellite imagery: https://earthexplorer.usgs.gov/
- A key remote sensing data catalogue and analysis platform today: Google Earth Engine.
Some resources provided by ESRI:
- ChangeMatters: Infrared Viewer – includes a tutorial [tour] on how to use their system.
- ArcGIS Pro Resources: The image classification wizard
There are an ever-growing number of satellites collecting data that can be used in a GIS environment.
List of some Earth Observation Satellites - A wiki listing of many of the earth-orbiting satellites.
Keywords
EMR, Spectral signatures, active / passive sensors, benefits (subpolygon info, cross boundary info, timely, etc.), NDVI