1 / 26

Aerial photography and satellite imagery as data input

Aerial photography and satellite imagery as data input. GEOG 4103, Feb 20th Adina Racoviteanu. Aerial photographs. "bird's-eye" view of the earth Photogrammetry = "the art or science of making measurements from aerial imagery". K-25 WWII Recon Camera. Camera systems.

patrick-riley
Télécharger la présentation

Aerial photography and satellite imagery as data input

An Image/Link below is provided (as is) to download presentation Download Policy: Content on the Website is provided to you AS IS for your information and personal use and may not be sold / licensed / shared on other websites without getting consent from its author. Content is provided to you AS IS for your information and personal use only. Download presentation by click this link. While downloading, if for some reason you are not able to download a presentation, the publisher may have deleted the file from their server. During download, if you can't get a presentation, the file might be deleted by the publisher.

E N D

Presentation Transcript

  1. Aerial photography and satellite imagery as data input GEOG 4103, Feb 20th Adina Racoviteanu

  2. Aerial photographs • "bird's-eye" view of the earth • Photogrammetry = "the art or science of making measurements from aerial imagery"

  3. K-25 WWII Recon Camera Camera systems High Quality Photographic Systems and the Digital Modular Camera

  4. angle Nadir Uncorrected Aerial photographs • Uncorrected aerial photos have distortions • radial distortion (due to lens curvature) • geometric distortions (due to inconsistencies in the • attitude of the airplane) • topographic distortions (due to relief)

  5. Uses of aerial photgraphy • Corrected images are often called orthoimages • GIS applications: land use and land-cover classification, terrain analysis, natural resource mapping, image backdrops for maps, temporal-change analysis, etc...

  6. Black and white aerial photography

  7. Color aerial photography

  8. Stereoscopy (three-dimensional imaging) any technique capable of recording three-dimensional visual information or creating the illusion of depth in an image;

  9. FUNDAMENTALS OF REMOTE SENSING • Energy source • Atmospheric interactions • Target interactions • Sensor records energy • Transmission to receiving station • Interpretation • Application

  10. Gamma Rays X rays Ultra-violet(UV) Visible (400 - 700nm) Near Infrared (NIR) Infrared (IR) Microwaves Weather radar Television, FM radio Short wave radio The EM Spectrum 10-1nm 1 nm 10-2mm 10-1mm 1 mm 10 mm 100 mm 1 mm 1 cm 10 cm 1 m 102m Violet Blue Green Yellow Orange Red

  11. PIXELS: Minimum sampling area One temperature brightness (Tb) value recorded per pixel

  12. Landsat Thematic Mapper (TM) • 30 m spatial resolution • 185 km FOV • Spectral resolution • 0.45-0.52 μm • 0.52-0.60 μm • 0.63-0.69 μm • 0.76-0.90 μm • 1.55-1.75 μm • 10.4-12.5 μm • 2.08-2.35 μm • 16 day repeat pass

  13. EOS Terra MODIS • Image Earth’s surface every 1 to 2 days • 36 spectral bands covering VIS, NIR, thermal • 1 km spatial resolution (29 bands) • 500 m spatial resolution (5 bands) • 250 m spatial resolution (2 bands) • 2330 km swath

  14. Digital processing2 steps needed: 1) Georeferencing: assign real world coordinates 2) Orthorectification: remove all the distortions

  15. Georeferencing • Assigning real world coordinates • Relating information (e.g., documents, datasets, maps, images) to geographic locations • will correct displacements Discrete georeferencing: through place names (i.e., toponyms) and place codes (e.g., postal codes) Geospatial referencing (e.g., longitude and latitude coordinates).

  16. Discrete georeferencingor Geocoding • The process of assigning a geographic location (e.g. latitude and longitude) to a geographic feature on the basis of its address. • E.g. address matching • mapquest.com

  17. Geocoding method • Based on a parcel centroid file that includes: • Street Name • Address • Nine-Digit ZIP Code • Main source for geocoding base map data is TIGER (http://www.census.gov/geog/www/tiger/)

  18. Ground Control Points (GCPs) • To georeference an image we need GCPs which are visible in the photographs, • e.g road intersections, stone wall boundaries, building corners, and solitary trees. • These points will be used to “tell” the GIS software: • where your image is in the world • how to correctly orient the photograph • correct for errors in photo-geometry.

  19. Road curves Rivers Squares Ground Control Points (GCPs) collection X • 24 GCPs – differentially • corrected GPS (vertical and • horizontal accuracy < 1m) • Orthorectification

  20. How many GCPs? • Depends on the amount of distortion in your photograph and your desired level of accuracy • mathematical formula applied to each pixel in the photo • first order (3 points min) does not distort, only shifts • second order (6 points min) • third order (9 points min) - distortions

  21. Georeferencing to an image file in ArcMap: Spatial data (polygons, points, etc.) can be aligned to an image file such as an historical map, satellite image, or aerial photograph.

  22. GCP Georeferencing terrestrial photography

  23. Orthorectification • mathematical process of removing the distortion caused by relief and the camera within a photograph so that the scale is uniform throughout the output image.

  24. Distortion vs.displacement • Distortion - Shift in the location of an object that changes the perspective characteristics of the photo. • Displacement - shift in the location of an object in a photo caused by change in elevation.)

  25. Orthorectification A sports stadium in downtown Toronto before and after rigorous orthorectificationImagery courtesy of DigitalGlobe

More Related