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Remote Sensing & GIS

Remote Sensing & GIS. Dr. Kodge B. G. Department of Computer Science, S. V. I. T. M. Udgir (MS), India kodgebg@svspm.edu.in. Remote Sensing.

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Remote Sensing & GIS

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  1. Remote Sensing & GIS Dr. Kodge B. G. Department of Computer Science, S. V. I. T. M. Udgir (MS), India kodgebg@svspm.edu.in

  2. Remote Sensing • Remote sensing is the acquisition of information about an object or phenomenon, without making physical contact with the object. In modern usage, the term generally refers to the use of aerial sensor technologies to detect and classify objects on Earth (both on the surface, and in the atmosphere and oceans) by means of propagated signals (e.g. electromagnetic radiation emitted from aircraft or satellites). The term RS was coined by Naval Research geographers of US in 1960s.

  3. Remote Sensing

  4. Remote Sensing • There are two main types of remote sensing: • Passive remote sensing detect natural radiation that is emitted or reflected by the object or surrounding area being observed. Reflected sunlight is the most common source of radiation measured by passive sensors. Examples of passive remote sensors include film photography, infrared etc. • Active remote sensing emits energy in order to scan objects and areas whereupon a sensor then detects and measures the radiation that is reflected or backscattered from the target. RADAR and LiDAR are examples of active remote sensing where the time delay between emission and return is measured, establishing the location, height, speed and direction of an object.

  5. RS & GIS Integration • The following terms may responsible for the success of any GIS application: • Geo-data acquisition • Data quality and resolution • Geo-reference and projections • Geo-data File formats • Software uses (front-end and back-end) • System requirements and designing • End user interface

  6. Electromagnetic RS • Two characteristics of electromagnetic radiation are particularly important for understanding remote sensing. These are the wavelength and frequency. Wavelength and frequency are related by the following formula:

  7. Electromagnetic RS E- Electric field, M- Magnetic Field and C- speed of light

  8. Imaging Characteristics of RS • The RS imaging system posses four major resolution characteristics. • Spatial resolution • The size of a pixel that is recorded in a raster image – typically pixels may correspond to square areas ranging in side length from 1 to 1,000 meters. • Spectral resolution • The wavelength width of the different frequency bands recorded – usually, this is related to the number of frequency bands recorded by the platform.

  9. Imaging Characteristics of RS • Radiometric resolution • The number of different intensities of radiation the sensor is able to distinguish. Typically, this ranges from 8 to 14 bits, corresponding to 256 levels of the gray scale and up to 16,384 intensities of color, in each band. • Temporal resolution • The frequency of flyovers by the satellite or plane, and is only relevant in time-series studies or those requiring an averaged or mosaic image as in deforesting monitoring.

  10. Extraction of metric information from remotely sensed images • Photogrammetry is used to obtain reliable measurements by means of photography. It uses computers and digital images to produce accurate topographic maps or orthoimages. • Non-Photographic RS System (Thermal infrared sensor, GPS, Reflected RADAR Signals). • Thematic Information (Image classification, LULC )

  11. Integration of RS & GIS • Separate but equal • Seamless integration • Total integration

  12. GIS Data Quality • The data quality refers to ‘fitness for use’ of data for intended applications. • Scope of geo-data quality (reliable, projected, relevant and current/updated). • Accuracy (roundup, inadequate survey ) • Precision (exact single/double float points) • Errors ( gross, systematic & random errors) • Uncertainty (lack of data confidence)

  13. Components of GIS data quality The seven dimensions for GIS data quality: • Lineage (documentation of when, why data) • Positional accuracy (closeness of coordinates) • Attribute accuracy (descriptive closeness, TIN) • Logical consistency (real world model) • Completeness (final spatial & thematic data) • Temporal accuracy (world time & DB time) • Semantic accuracy (label with relational data)

  14. Sources of Errors in GIS • Sources Inherent Operational Map Projection Y N Map Scale Y N Field survey measurements Y Y Image analysis Y Y Sampling design Y Y Digitizing Y Y Raster to vector Y N Overlay analysis Y N Attribute data input Y Y

  15. Finding & Modeling Errors • Checking for errors • Probably the simplest means of checking for data errors is by visual inspection. • Various statistical methods can be employed to help pinpoint potential errors. • Estimating degree of an error helps in controlling and correcting errors.

  16. Internet Resources of GIS • The Internet contains a tremendous amount of information resources pertaining to the study and use of geographic data, Scientific papers on the concepts, techniques, and applications of GIS as well as information about hardware and software products. • Students are encouraged to take advantage of the power of search engines: Google, AltaVista, Yahoo.

  17. Where to start search GIS Information jump Stations • www.gis.com (ESRI portal) • GeoCommunity (www.geocomm.com) • www.gislinx.com • http://map.lib.umn.edu (Minnesota Univ.) • http://www.calmit.unl.edu (Nebraska linkon) • http://rst.gsfc.nasa.gov/

  18. Pointers to Info. Resources • NASA EOS (www.eos.nasa.gov) • USGS-NIMA (egsc.usgs.gov/nimamaps) • NOAA (www.noaa.gov) • USGS-SRTM (www.seamless.usgs.gov) • OGISC (www.opengeospatial.org) • NRSC-Bhuvan (www.bhuvan.nrsc.gov.in) • SOI (www.surveyofindia.gov.in) • NATMO (www.natmo.gov.in)

  19. Pointers to Data Resources • ESRI data online (www.esri.com/data) • Alexandria project (www.alexandria.ucsb.edu) • CIESIN (www.ciesin.org) • ARKANSAS CAST (www.cast.uark.edu) • GIS data depot (www.data.geocomm.com) • DIVA-GIS (www.diva-gis.org/data) • Microsoft Terra server (www.terraserver.com) • SRTM DEM (http://srtm.csi.cgiar.org/)

  20. Pointers to Product Info. • Computer manufacturer’s sites and • ERDAS Inc. (www.erdas.com) • ESRI (www.esri.com) • Intergraph (www.intergraph.com) • PCI Geomatics (www.pcigeomatics.com) • MapInfo (pbinsight.com/welcome/mapinfo) • Oracle Corp. (www.oracle.com) • Geoeye (www.geoeye.com)

  21. Internet based GIS applications • Google earth (www.earth.google.com) • NASA world wind-worldwind.arc.nasa.gov • ARG GIS earth explorer (maps.esri.com) • NASA EOS (svs.gsfc.nasa.gov) • Indian ATLAS (atlas.gisserver.nic.in) • DST-NRDMS-NSDI (http://nsdiindia.gov.in) • VISA card ATM Locator-visa.via.infonow.net

  22. GIS & RS Journals • American Cartographer • Cartography and GIS • IEEE T on Computers & Geosciences • Geometica • Int. Journal of Remote Sensing • Transactions in GIS • Int. journal of GIS • Journal of Remote Sensing of Envi.

  23. Digital Terrain Model • DEM, DSM and DTM. • A digital terrain model is a topographic model of the bare earth – terrain relief - that can be manipulated by computer programs. The data files contain the spatial elevation data of the terrain in a digital format which usually presented as a rectangular grid.

  24. DTM

  25. DTM

  26. DTM • Mappers may prepare digital elevation models in a number of ways, but they frequently use remote sensing rather than direct survey data. One powerful technique for generating digital elevation models is interferometric synthetic aperture radar: two passes of a radar satellite (such as RADARSAT-1 orTerraSAR-X ) are used. DTM files formats like, DEM, DTED, HDT, Gird, xyz, dat, csv, etc. are available.

  27. Approaches

  28. Contours

  29. TIN

  30. DTM Acquisition • Methods Accuracy Area • Ground Survey VH Small Photogrammetry H Large Engg Proj. Cartography L Nation wide Lidar/Radar H Wide GPS H Medium

  31. DTM Visualization • ARC TIN & 3-D Analyst of ESRI • GeoTerrain of Bentley Systems • IMAGINE of ERDAS • MGE Terrain of Modular GIS software • Terraview • FLY of EASI Orthoengine • MATLAB of Mathworks • Global Mapper

  32. DTM Applications • Surveying & Mapping • Hydrological & Geomorphological • Geoscientific • Engineering • Natural Resource Management • Military • National developments

  33. GIS Implementation & Project Management • GIS Project Planning • GIS software evaluation and selection • Hardware consideration and acquisition • GIS Database design methodologies • Software Engineering in GIS • Software design methodologies • System Analysis & User Requirements

  34. GIS Issues and Prospects • GIS Implementation (data, ownership, misusing, privacy, updating, documentation) • Technical issues (Evaluation, speed, memory and Management) • Integration with other applications. • Issues pertaining to people.

  35. The Trend of GIS Development • Enterprise computing and GIS • Spatial data warehouses • Interoperability and Open GIS • National spatial data Infrastructure • Internet and its impact on GIS

  36. Frontiers of GIS Research • Spatial data acquisition & Integration • Distributed computing • Extensions to Geographic representations • Scale • Spatial analysis in GIS environment • Future of spatial information • GIS and Society • Education and training.

  37. Thank You..

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