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Satellite eyes observe our world: An intro to remote sensing

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A gentle introduction into remote sensing by Harald Schernthanner, Christian Kuntzsch and Andreas Frigge. The presentation was held at Maytime BER on march 1st.

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Satellite eyes observe our world: An intro to remote sensing

  1. 1. Satellite eyes observe our world: An intro to remote sensing Christian Kuntzsch @DeEgge Andreas Fricke @incentivious Harald Schernthanner @hatschito
  2. 2. • What is remote sensing ? History and future ? • Applications, e.g. mapping permafrost • Tutorial: How to derive a vegetation index from Sentinel-2 data ?
  3. 3. Remote Sensing "Remote Sensing is the science and art of obtaining information about an object, area, or phenomenon through the analysis of data acquired by a device that is not in contact with the object, area, or phenomenon under investigation.“ Lillesand, T., Kiefer, R. W., & Chipman, J. (2014). Remote sensing and image interpretation. John Wiley & Sons.
  4. 4. History of remote sensing 1914 WWI 1860 Boston 1854 Nadar 1860 Boston
  5. 5. History of remote sensing 1940´s Colored photography 1942 - Kodak patents first false color I.R. sensitive film CIR (coloured inrared)
  6. 6. Discovering historical imagery in google earth Kreuzberg, 12/1943
  7. 7. History of remote sensing Kreuzberg 03/2015
  8. 8. Milestone in remote sensing - 1940 Color infrared CIR - 1972: Launch of ERTS-1 = Landat 1. Satellite copy of CIR sensor - 80m pixel resolution - 1986: Launch of SPOT-1 - 1999: Landsat 7 ETM - 2000: Shuttle SRTM Mission - 2001: Digitalglobe Quickbird - 61 cm pixel resolution - 2005: Google Inc. releases Keyhole, http://earth.google.com - 2007:- 2014: WorldView 3: Eight band multispectral: 0,31 cm geometric resolution, SWIR: 3,7 - 2015: Launch of Sentinel-2 - 2016 Nano satellites - permanently available HD video from space:
  9. 9. Future ? Nano - Satellites Unmanned aerial vehicles, UAV
  10. 10. How many satellites are in space?
  11. 11. 2,271 satellites: Stuff in Space ?
  12. 12. Where are the satellites? Real time satellite tracking
  13. 13. Applications ? - Primary data source for mapping - Land use/cover classification - Land change - Environmental analysis - Geography / Geology / Hydrology / Forestry - ….. Aral lake shrinking timelapse, classical example
  14. 14. ANDREAS PERMAFROST
  15. 15. Where to get data from ? • Commercial data providers: Price: around 20 US$ / sq. km with minimum order of 24 sq. km = Berlin scene ca. 18 000€ • https://browse.digitalglobe.com/ • http://eyefind.rapideye.com/ • Free data sources: • 15 free data sources: http://gisgeography.com/free-satellite-imagery-data- list/ • USGS Earth Explorer: http://earthexplorer.usgs.gov/ • Sentinels scientific data hub: https://scihub.copernicus.eu/ • How to search Sentinel data: http://www.digital- geography.com/downloading-sentinel-satellite- imagery/#.VtVRDpPhBsM
  16. 16. Where to get data from ? • Data search and preprocessing can be very time consuming! • Knowledge about the data is necessary: • Sentinel-2 processing levels
  17. 17. Sentinel-2a • 6 satellite missions by ESA • Satellite eyes see more! • Sentinel-2A: 13 bands / 10 days revisit time
  18. 18. Data & preprocessing • Downloaded scene covering Berlin: 8GB of data • Acquisition data: 24.12.2015 • Subset and export as geotiff was done in the Sentinel toolbox: http://step.esa.int/main/toolboxes/snap/ • Open source, but unstable and memory consuming, but getting better from version to version… • Dataformat only can be handled by SNAP
  19. 19. Entire scene in false colors: 200 km east-west 320 km north - south Berlin
  20. 20. Video tutorials by Luca Congedo, developer of the semiautomatic classification plugin https://www.youtube.com/user/f romgistors Commercial image processing software Open source image processing software Monteverdi 3.0
  21. 21. NDVI of Berlin • NDVI = Normalized differenced vegetation index • Index of photosynthetic activity of plants • Active vegetation absorbes light in red part of the EMS (electromagnetic spectrum) and reflects in the NIR part IMPORTANT INFORMATION VISUALLY AWFUL
  22. 22. Loading raster data in QGIS GeoTIFF Open raster icon
  23. 23. False color in QGIS
  24. 24. NDVI in QGIS NDVI = (NIR-Red)/(NIR+Red)
  25. 25. Raster calculator QGIS Raster substraction in QGIS
  26. 26. Raster calculator in QGIS
  27. 27. NDVI formula in QGIS Raster calculator Band 1: red, Band 2: green, band 3: blue, band 4: near infrared Expression: float(image@4 - image@1) /(image@4 + image@1) float: conversion from integer to floating point @1…4 : band number
  28. 28. NDVI result
  29. 29. NDVI classes NDVI Barren rock, sand, snow -1 <0,1 Sparse vegetation >0,1 - 0,5 Dense vegetation >0,5 - 1 Ranges from -1 to 1: USGS classification http://phenology.cr.usgs.gov/ndvi_foundation.php
  30. 30. Classify NDVI result Right click on data layer -> properties -> style
  31. 31. Classified NDVI
  32. 32. Want to learn more ? • NASA remote sensing tutorial: http://earthobservatory.nasa.gov/Features/Remote Sensing/ • Great tutorials and youtube channel by Luca Congedo: https://www.youtube.com/user/fromgistors • http://fromgistors.blogspot.com/search/label/Tutor ial?max-results=5
  33. 33. Questions ? Thank you for your attention!

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