Introduction to Aerial Photography Interpretation

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Introduction to Aerial Photography Interpretation. *DRAFT*. History of Aerial Photography. 1858 - Gasparchard Tournachon photographs Bievre (outside Paris) from a balloon 1860 - James Black photographs Boston Harbor from a tethered balloon (earliest existing - perhaps first in US). - PowerPoint PPT Presentation

Transcript of Introduction to Aerial Photography Interpretation

  • Introduction to Aerial Photography Interpretation*DRAFT*

  • History of Aerial Photography1858 - Gasparchard Tournachon photographs Bievre (outside Paris) from a balloon1860 - James Black photographs Boston Harbor from a tethered balloon (earliest existing - perhaps first in US)Boston Harbor 1860

  • History of Aerial PhotographyUS Civil War - Union General George McClellen photographs confederate troop positions in VA. 1882 - E.D. Archibald, British Meterologist takes first kite photograph1903 - Pigeon cameras1906 - George Lawrence photographs San Francisco after great earthquake and fire

  • History of Aerial Photography1906 - George Lawrence photographs San Francisco after great earthquake and fireSan Francisco in Ruins, by George Lawrence, was taken with a kite 6 weeks after the Great 1906 Earthquake.

  • History of Aerial Photography1909 - Wilbur Wright and a motion picture photographer are first to use an aircraft as a platform - over Centocelli, ItalyWW2 - Kodak develops camouflage-detection filmused with yellow filtersensitive to green, red, NIR camouflage netting, tanks painted green show up as blue instead of red like surrounding vegetation

  • History of Aerial Photography2002 - Field workers document the effects of the M7.9 Denali Fault Earthquake with digital cameras from planes and helicoptersMosaic view of rock avalanches across Black Rapids Glacier. Photo by Dennis Trabant, USGS; mosaic by Rod March, USGS.

    Aerial view of the Trans-Alaska Pipeline and Richardson Highway. Rupture along the fault resulted in displacement of the highway. Photo by Patty Craw, DGGS.

  • History of Aerial Photography 2006 - Effie Kokrine Charer School Students take digital flotographs at Twin Bears Camp, Alaska

  • Types of Air Photos High (horizon) & Low (no horizon) ObliqueHigh oblique photo by Austin Post. Oasis Branch, Baird Glacier, Alaska 08/09/61.

  • Types of Air PhotosVerticalStereo/3DColor infrared (CIR) stereopair of the Galbraith Lake, Alaska area.

  • Types of Air PhotosUsing a stereoscope to view CIR stereopairs in the field

  • Aerial CamerasA large format oblique cameraKeystones Wild RC-10 mapping camera

  • Film TypesPanchromatic (B& W)most often used in photogrammetrycheapColoreasy to interpretfuzzy due to atmospheric scattering

  • More Film TypesBlack & White Infraredpopular for flood mapping (water appears very dark)vegetation mappingsoils - dry vs. moistFalse Color Infrared (CIR, Standard False Color)vegetation studieswater turbidity

  • CIR and True Color Film Type ExamplesCIRTrue Color

  • ProductsContact Prints - 9x 9sFilm Positives - DiapositivesEnlargementsMosaicsIndices (a reference map for air photo locations)Rectified Photos (can import into a GIS)Orthorectified Photos (can import into a GIS)Digital Orthophotos (can import into a GIS)

  • Printed Information/AnnotationAlong the top edge, youll find:Date of Flight Time - (optional - beginning/end of flight line)Camera focal length in mm (optional - frequently 152.598 mm = 6)Nominal scale (RF)Vendor/Job #Roll #, Flight line & Exposure #

  • Determining Photo ScaleSometimes (at beginning and end of a flight line) Nominal Scale is printed at the top of a photo, usually as RF

  • Determining Photo ScaleMore likely you will have to compute scale using ruler, map, calculator and this formula 1(MD)(MS)/(PD)where:MD = distance measured on map with ruler (cm or in)MS = map scale denominator (e.g., 24,000 for USGS Quads)PD = photo distance measured in same units as map distanceRF =No scale here.

  • Determining Photo ScaleYou can also roughly estimate scale from cultural features if there are any in the image (problematic in Alaska), e.g., tracks, athletic fields, etc.

  • Determining Photo OrientationLabels and annotation are almost always along northern edge of photoSometimes eastern edge is usedOnly way to be certain is to use a map

  • Photointerpretation: Recognition ElementsShapeSizeColor/ToneTexturePatternSiteAssociationShadow

  • Photointerpretation: Recognition ElementsShapecultural features - geometric, distinct boundariesnatural features - irregular shapes and boundariesShape helps us distinguish old vs. new subdivisions, some tree species, athletic fields, etc.The pentagonMeandering river in AlaskaInterior Alaskanvillage (note airstripnear top of image)

  • Photointerpretation: Recognition ElementsSizerelative size is an important cluebig, wide river vs. smaller river or sloughapartments vs. housessingle lane road vs. multilane

  • Photointerpretation: Recognition ElementsColor/Toneconiferous vs. deciduous treesCIR - Spruce forest (black) with some deciduous (red) trees.CIR Deciduous(leafy) vegetation(red).CIR- Mixed spruce And deciduous foreston hillside with tundrain valley bottom.

  • Photointerpretation: Recognition ElementsColor/ToneTurbidity - relative amounts of sediment in waterVegetation presence or absenceCIR The big, light blue river in the lower part of the image is the Tanana River. It carries fine particles eroded by glaciers in the Alaska Range.

    The smaller dark blue river flows south from top of the image to the Tanana River. It is fed by surface runoff and groundwater sources and does not carry much sediment.

    Unvegetated gravel bars look bright bluish white.Photo by Maria SoteloRelatively clear ChenaRiver waterTurbid Tanana River water

  • Photointerpretation: Recognition ElementsTexturecoarseness/smoothness caused by variability or uniformity of image tone or colorsmoothness tundra, swamps, fields, water, etc.coarseness - forest, lava flows, mountains etc.CIR- Marshy tundra with manysmall ponds.CIR - Bare roundedMountains (blue)surrounded by tundraand lakes. CIR - Tundra showing drainage pattern

  • Photointerpretation: Recognition ElementsPatternoverall spatial form of related featuresrepeating patterns tend to indicate cultural features - random = naturaldrainage patterns can help geologists determine bedrock typeA dendritic pattern is characteristic of flat-lying sedimentary bedrock

  • Photointerpretation: Recognition ElementsSitesite - relationship of a feature to its environmentdifferences in vegetation based on location: In interior Alaska, black spruce dominant on the north side of hills and deciduous trees on the south side.Vegetation is often has different characteristics by rivers than away from themMeandering Alaskan riverInterior Alaskan hillsideN

  • Photointerpretation: Recognition ElementsAssociationidentifying one feature can help identify another - correlationThe white cloud and black shadow have the same shape, they are relatedThe long straight airstrip near the top of the image indicates that there might be a village or settlement nearby

  • Photointerpretation: Recognition ElementsShadowsshadows cast by some features can aid in their identificationsome tree types, storage tanks, bridges can be identified in this wayshadows can accentuate terrainThe mountain ridge onthe right side of this imageis accentuated by shadow

  • Getting your very ownGeoData Center, UAF Geophysical Institute(907) 474-7487 or (907) 474-7598 (8am to 5 pm Alaska time)email: [email protected] or [email protected]:http://www.gi.alaska.edu/services/geodata10x10 CIR contact prints prices per frame - $18.00 (other sizes available)Digital files low resolution (300 dpi) $12.00, high resolution (1200 dpi) $51.00 (other resolutions available)Contact the GeoData Center to request images. A staff person will find the imagery and respond to your request. Alternatively, browse the website and make a request based on what you find. There are more images in the GeoData archive than what you will see posted on the website.Helpful to know lat./long. of your area of interest

  • Getting your very ownUSGS EROS Data Center(800) 252-4547 (8am-4pm central time)email: [email protected]:http://edc.usgs.gov/Digital files B&W or CIR prices per frame medium resolution $3.00, high resolution $30.00 (other resolutions available)Prints not available, but, contact information is available on the USGS website to direct people to vendors who can make prints from the digital data from USGSRequires using Earth Explorer to web search for Alaskan imagery http://edcsns17.cr.usgs.gov/EarthExplorerHelpful to know lat./long. of your area of interest

    Nominal Scale. The nominal scale of a map is the amount by which the full-sized model of the Earth is shrunken to produce the generating globe used in the projection process that produced the map. The map's actual scale will equal it's nominal scale at the map's point(s) or line(s) of tangency. However, since virtually all map projections distort scale, a map's actual scale will change from place to place across the map. Thus, it is not correct to say that a map's actual and nominal scales are identical at all points on the map. When a map shows its scale (using a scale bar, a verbal description like "1:24,000", or any other means), it is almost always reporting its nominal scale. The map's actual scale will differ from the reported nominal scale at all points other than the map's point(s) or line(s) of tangency. http://www.warnercnr.colostate.edu/class_info/nr502/lg4/glossary/nominal_scale.html