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Remote Sensing Image Interpretation in Geological Works
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Remote Sensing Image Interpretation in Geological Works


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  • 1. TWC Remote Sensing Image Interpretation in Geological works Xiaogang (Marshall) Ma Tetherless World Constellation Rensselaer Polytechnic Institute Geo I course, 2013-11-14
  • 2. TWC • Acknowledgements – The majority of this lecture is from Dr. Tsehaie Woldai’s lecture ‘Image Interpretation - Part 1’ in a course RS & GIS for Earth Resources Exploration at ITC, Enschede, The Netherlands, in 2009 2
  • 3. TWC 1. Geological mapping, remote sensing data and image interpretation
  • 4. TWC Geological Mapping Geologists follow paths of exploration and discovery in quest of solutions to some of society's most challenging problems. Geological mapping is the starting point for all understanding of the earth's crust and hence for all logically conceived programs of exploration for earth resources North Africa: Landsat MSS (b7,5,4) 4
  • 5. TWC Printed maps and digital maps 日本語 / English English / Español / Português
  • 6. TWC Geological map online services OneGeology • 116 nations participating by middle 2010 • 50 of them providing geodata services online • Most data are in English
  • 7. TWC Remote Sensing (RS) • Use of Earth orbiting satellites to capture information about the surface and atmosphere below • Satellites vary depending on how much detail can be seen, what parts of the electromagnetic spectrum are sensed • Signals transmitted to Earth receiving stations where they are transformed for dissemination as digital images Courtesy:
  • 8. TWC Two main types of RS • Passive RS: – detect natural radiation (e.g., sunlight) that is emitted or reflected by the object or surrounding areas • Active RS: – emits energy (e.g., laser light) in order to scan objects and areas whereupon a sensor then detects and measures the radiation that is reflected or backscattered from the target Images from:
  • 9. TWC A few RS systems • • • • • • • • Airphotos Airborne Multispectral/Hyperspectral Scanners Airborne Thermal Scanners Airborne Radar Satellite Photography Satellite Digital Imagery Side-Scan Sonar Laser Altimeters
  • 10. TWC Night lights of Australia as observed by the Visible Infrared Imaging Radiometer Suite (VIIRS) on the Suomi NPP satellite in April and October 2012
  • 11. Fires TWC More information:
  • 12. TWC Remote Sensing RS for geology What do geologists want to know? • Composition of earth materials Detect, identify, measure geological features • Dynamic processes in the Earth Monitor and measure geodynamic processes • Environmental impact Identify, monitor and assess 12
  • 13. TWC Why the need for remote sensing data? • RS  A multifaceted TOOL for geology • Analysis of RS data for Geological applications – – Measure physical characteristics of geo-bodies Geological interpretation 13
  • 14. TWC Why the need for remote sensing data? 1. 2. 3. 4. 5. Synoptic View Construct regional geological maps, useful for small scale analyses Planning field traverses to sample and verify various units for detailed mapping Understand the spatial distribution and surface relationships between the units Cost, time A synoptic view of regional scale is a much different perspective than point ground observations when trying to map lithological or structural elements. 14
  • 15. TWC Broad Regional Coverage Synoptic View 15 Landsat TM of the Bogda Shan Mts., Xinjiang Uugur Aut. Region, China
  • 16. TWC Analyzing Complex Areas Uniform Accuracy and Precision Metavolcano-Sedimentary Assemblage Gneissic Terrain Ophiolite Assemblage Gneissic Terrain Granitoids 16
  • 17. TWC Dataset in hand for Image Interpretation ASTER data (b3n/3b) Perspective view Digital Terrain Model 17
  • 18. TWC Dataset in hand for Image Interpretation Creation of DEM’s/Anaglyphs Algeria Morocco 18 Anaglyphs From: Drury, 2002
  • 19. TWC Possibility of stereo viewing SPOT, Radarsat, etc. Southern Image Northern Image Stereo Pair - New York City USA 19
  • 20. TWC Geoscience knowledge management system Needs of Geological Surveying Organizations Priorities of Geological Surveys are changing - away from publication of maps and related documents towards maintaining a geoscience knowledge management system of reusable elements from which users can obtain specific responses to meet their specific needs, with maps seen as illustrative visualizations, not as end products Text c. British Geological Survey 20
  • 21. TWC Geoscience knowledge management system Needs of Geological Surveying Organizations Geological Survey organizations also cannot afford to send their staff into the field indefinitely mainly because they cannot afford it anymore Hence there is a dire need for image interpretation prior to fieldwork mapping to reduce cost, time and energy. Text c. British Geological Survey 21
  • 22. TWC Image interpretation - Definition Image interpretation can be defined as: • • • The study of the imaged objects using the image/photo interpretation criteria; The extraction of those features relevant to the object of study; The analysis of the selected features with the objective to come to a deduction of their significance for the specific field of study. 22
  • 23. TWC 2. Principles and steps in RS image interpretation
  • 24. TWC Knowledge-driven image interpretation Leading principles Exploits image data from multiple sensors for interpretation in a GIS environment Capitalizes on use of available information  X1     X2  X  3   ....   ....   .....  X   n Traverse 200422 Employs qualitative & quantitative interpretation methods Plays an important role in fieldwork planning 24
  • 25. TWC What information can be obtained from RS images • • • • • • • Topographic pattern Drainage pattern Landform units Lithological/rocks units Geological structures Mineral deposits location Susceptible area for erosion, mass-movement, earthquake, volcanic, etc.
  • 26. TWC Geological RS image interpretation • The aim is to obtain lithological, stratigraphy and geological structure • The status is not as an alternative of field geology; fieldwork always carried out to check the result of the image interpretation; the results of the image interpretation are supposed similar with data from other sources.
  • 27. TWC Geological map resulting from RS image interpretation • Lithological units: may composed of single rock or group of rocks • Geologic structures indicators: dip slope, bedding plane • Continue or discontinue of the bed layers • Indicators of fault and unconformity • Landform units • Drainage pattern, can be used to identify the lithology and structure • Control point, important location, ground control
  • 28. TWC How to upgrade the geoscience knowledge base through the use of RS? • How do we actually extract geological information from images? • What are the criteria? • Which methods can be employed? • How can it support mapping? • What are the success factors? 28
  • 29. TWC Image characteristics for interpretation purposes • • • • • • • Tone Texture Pattern Shape/form Site Association Shadow
  • 30. TWC How to interpret the lithology • Lithological units are easily to identify from remote sensing image (especially aerial photograph): – – – – – – Sandstone Shale stone Limestone A certain igneous and metamorphic rocks Unconsolidated material, such as: sand, gravel, clay Intercalation resistance and non resistance rocks
  • 31. TWC Igneous rocks • Based on mineral composition: – Acidic: light photo tone – Intermediate: light to medium photo tone – Basic: dark to dark photo tone • Extrusive rocks: – – – – – – Associate with volcanic landform Porosity and permeability: high External drainage Basic lava: shield volcano, joint are predominate Acidic lava: bocca, spatter cone, lava blister Intermediate lava: strato volcano • 3.Intrusive rocks: – – – – Homogeny Topography hummocky (humid) and sharp (arid) Joint: frequent Drainage pattern with low density
  • 32. TWC Metamorphic rock • Massive topography, stratigraphy not clearly appear • Permeability is low; drainage density high to medium; drainage pattern: dendritic, trellis or parallel. • Quartzite: resistant, massive topography, low permeability, dendritic, trellis; gray photo tone • Marble: in arid and semi arid resistant, in humid similar to limestone • Slates: low resistant, high drainage density, dendritic; dark to medium gray • Gneiss: resistant, massive topography, low permeability, dendritic, trellis; gray photo tone
  • 33. TWC Geological structure • FLAT-LAYING BEDS: – Contrasting tone of different sedimentary rocks – Break of slope along the contour – Dendritic drainage pattern • DIPPING BEDS (FOLDS) – Topographic surfaces coincide with bedding surface – Asymmetrical slope can be used to determine the direction of the dip – Pattern of outcrop on valley can be used to determine the direction of the dip – Major stream usually flow parallel to the strike of the stratified beds.
  • 34. TWC – Linear features/lineaments, thin rather than short, in regular direction – Intersecting joint approximately at right angles (vertically, dipping) give a blocky pattern of the topography. – In fine grained clastic rocks joint are generally more closely spaced • FAULTS – Linear features/lineament – Triangle facet – Alignment of vegetation, straight of river/stream segment, alignment of lakes, ponds and springs – Changes of tone, drainage and erosional features on opposite of linear features – Alignment of topography
  • 35. TWC Let’s take the Doon Valley (Dehradun Area), India as an example
  • 36. TWC Dehradun LOCATION
  • 37. TWC Let’s first review a slide from the lecture ‘Crustal Deformation & Mountain Building (Orogenesis)’
  • 38. Plate tectonics: Continent - Continent extent, deformation from collision TWC 38
  • 39. TWC Geology of the Doon Valley – India collision with Asia • During the Early Cretaceous (100 to 150 million years ago), India broke away from Gondwana and began drifting North – Oceanic lithosphere was consumed at a subduction zone along the southern margin of Asia • About 40 to 50 million years ago, India collided with Asia – But because India was too light to subduct, it thrust under Asia
  • 40. TWC Convergent Boundary Continent - Continent Model for India and Asia Collision 40
  • 41. TWC Continued Convergence 41
  • 42. TWC The Doon Valley Geology 42
  • 43. TWC Landsat • The Landsat program is the longest running enterprise for acquisition of satellite imagery of Earth. – Landsat 1 (originally named Earth Resources Technology Satellite 1): launched July 23, 1972, terminated operations January 6, 1978 – Landsat 2: launched January 22, 1975, terminated January 22, 1981 – Landsat 3: launched March 5, 1978, terminated March 31, 1983 – Landsat 4: launched July 16, 1982, terminated 1993 – Landsat 5: launched March 1, 1984, still functioning, but severe problems since November 2011. On December 26, 2012, USGS announced that Landsat 5 will be decommissioned. – Landsat 6: launched October 5, 1993, failed to reach orbit – Landsat 7: launched April 15, 1999, still functioning, but with faulty scan line corrector (May 2003) – Landsat 8: Landsat Data Continuity Mission was launched February 11, 2013. May 30, 2013 Landsat Data Continuity Mission was turned over to USGS and renamed Landsat 8.
  • 44. TWC Landsat 7 before launch Landsat ETM+ The main instrument on board Landsat 7 is the Enhanced Thematic Mapper Plus (ETM+). Landsat 7 and ETM+ Characteristics: Band Number Name 1 2 3 4 5 6 7 Pan Blue Green Red Near Infrared Shortwave IR-1 Thermal IR Shortwave IR-2 Panchromatic Spectral Range (µm) .45 to .515 .525 to .605 .63 to .690 .75 to .90 1.55 to 1.75 10.40 to 12.5 2.09 to 2.35 .52 to .90 Ground Resolution(m) 30 30 30 30 30 60 30 15 Source:
  • 45. TWC
  • 46. TWC Spectral bands are part of optical spectra of polyatomic systems. Current Landsat collection is that of seven bands, including several in the infra-red spectrum, ranging from a spectral resolution of 0.07 to 2.1 μm. Band 4: Red Band 5: Green Band 3: Blue Note this is a false color image: an image that depicts an object in colors that differ from those a photograph (a "true-color" image) would show. the true color image of an area Band 3: Red Band 2: Green Band 1: Blue
  • 47. TWC Image interpretation and project schedule Data collection Georeferencing !!! Georeferencing is often underestimated. If not properly dealt with from the start it will be a pain in the neck throughout the live cycle of a project. Integrated Image Interpretation Fieldwork, ground truthing Synthesis and compilation 47
  • 48. TWC Different Steps in Image Interpretation Data Remotely sensed datasets Discrimination Are targets distinguishable from background? (“separability”) Detection Selective picking out things of informational value Categorization Identification Classification Partitioning and coding “Recognition” Is a discipline-oriented kind of classification Information 48
  • 49. TWC Sensor Return Relate to geology Not related Discriminative Not discriminative Not diagnostic Diagnostic Identification possible Categorization possible Categorization not possible Analysis not possible 49
  • 50. TWC Recognition process in visual analysis Unknown categories Feedback Spontaneous Recognition External Information Known classes
  • 51. TWC Spontaneous Recognition A D C • memory • experience • “data bank” • etc. B
  • 52. TWC Recognition process in visual analysis Unknown categories Feedback Spontaneous Recognition External Information Known classes 52
  • 53. TWC Logical Inference “man’s superior intelligence” • Knowledge of the area • Past experience in similar terrain • Image photo interpretation characteristics
  • 54. TWC The more explicit rule for photo/image interpretation: In the image interpretation process, the objects of our interest are Measured* in terms of variations in: SHAPE SIZE TEXTURE TONE ** ORIENTATION PATTERN ASSOCIATION * Measurements done at - nominal scale (coding) - ordinal scale (>,<) - seldom used: interval, ratio ** Descriptive terms are often used SITE 54
  • 55. TWC The interpretation element: PATTERN Drainage pattern Internal Draiange 1 Pinnate Dendritic Pectinate Special Patterns Sinkhole Deranged 2 Barbed Dichotomic Dot Angulate Rectangular Contorted Thermokarst Sub-parallel 3 Anastomotic Knob & Kettle Parallel 4 Gilgai Radial Lacunate Braided 5 Annular 55
  • 56. TWC Patterns of folded and faulted rocks Asymmetrical + Thrust Fault Cross fault through nose 56
  • 57. TWC The rule of the ‘V’s 1. Dip direction != slope direction – “V” of layer in stream points in dip direction 2. Dip direction = slope direction && dip amount of layer > slope angle – “V” of layer in stream points in dip direction 3. Dip direction = slope direction && dip < slope – V” of layer in stream points opposite to dip dir 3 is the anomalous case!
  • 58. TWC Different types of Faults
  • 59. TWC Remember these from our recent lectures? 59
  • 60. TWC Remember these from our recent lectures? 60
  • 61. TWC Remember these from our recent lectures? 61
  • 62. TWC Remember these from our recent lectures? 62
  • 63. TWC Remember these from our recent lectures? 63
  • 64. TWC What is this? Hmm… circular pattern 64
  • 65. TWC It is a crater! Manicouagan crater It is thought to have been caused by the impact of a 5 km (3 mi) diameter asteroid about 215.5 million years ago (Triassic Period). 65
  • 66. TWC Recognition process in visual analysis Unknown categories Feedback Spontaneous Recognition External Information Known classes 66
  • 67. TWC External Information
  • 68. TWC Different types of images Flat Irons on Landsat TM+
  • 69. TWC Flat Irons on Anaglyph 69
  • 70. TWC Flat Irons/folding/ lineaments on Shaded SRTM Data STRM – Shuttle Radar Topography Mission
  • 71. TWC Faults on Landsat ETM+
  • 72. TWC Folding on Landsat TM+ 72
  • 73. TWC Folding on Anaglyph
  • 74. TWC Fieldwork Representation of Geological Information 74
  • 75. TWC Fieldwork Representation of Geological Information TW, 2000 TW, 2000
  • 76. TWC Before we end the lecture… • Landsat is only one of the various sources for remote sensing images • And now days there are various RS systems and various of RS data formats • And various software programs available • Yes, geological remote sensing is an active field of research!
  • 77. TWC Recognition Processes Self Test 1 relevant to the quiz in next week Analyze a part of the Landsat TM Coverage of the Doon Valley. 1. What is the first important thing you have to do in order to interpret this image? 2. Spontaneous delineation of lithological boundary is possible, but is it evident to do direct identification of the rock type? 3. Why do we see variations in color? 4. Look into contact A and B. Are they also geological boundaries? 5. Where do you think is the drainage divide? 6. Is Unit C the same outcrop as Unit D? 7. Compare the image with the “Geological Map of the Dehradun Area” given in class. Could you relate the lithological units defined in the geological map with the image? 8. What can guide you to better definition of the lithological units? 77
  • 78. TWC Thank You Image c. British Geological Survey