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Calculating Visual Connectivity …an animated series of slides demonstrating 2D and 3D

Calculating Visual Connectivity …an animated series of slides demonstrating 2D and 3D visual connectivity from increasing viewer height (0’ to 20,000’). Prepared by Joseph K. Berry Keck Scholar in Geosciences, University of Denver

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Calculating Visual Connectivity …an animated series of slides demonstrating 2D and 3D

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  1. Calculating Visual Connectivity …an animated series of slides demonstrating 2D and 3D visual connectivity from increasing viewer height (0’ to 20,000’) Prepared by Joseph K. Berry Keck Scholar in Geosciences, University of Denver Principal, Berry & Associates // Spatial Information Systems (BASIS) Fort Collins — jberry@innovativegis.com Website www.innovativegis.com/basis

  2. Mount St. Helens Topography(project area) Raster Image 7,799 Feet 6,312 Feet Viewer Location Second Ridge 7,799 Feet 3,219 feet First Ridge 6,312 Feet Point of Interest3,267 feet 466 row 327 col + + 6 miles North  Digital Elevation Model (DEM) (Grid Surface configured as 466 rows by 327 columns with 30m cells ) 0 miles

  3. Calculating Visual Connectivity(Approach) POI Height Rise Similar triangles can be used to determine the minimum POI height needed to be visibly connected … Tangent = Rise / Run1 POI Elevation = (Tangent * Run2) + Viewer Elevation Run1 Run2 Viewer Location First Ridge (300c, 114r) Point of Interest + First Ridge Elevation (134c, 325r) 6,312 Feet Point of Interest Minimum Visible Elevation 11,380 Feet Seen N Viewer Elevation 3,219 Feet Not Seen . Viewer Location (33c, 454r) + 6 miles North  Viewshed at 0 feet rise 0 miles

  4. Calculating Visual Connectivity(Approach) Similar triangles can be used to determine the minimum POI height needed to be visibly connected … Tangent = Rise / Run = (6312 ft – 3219 ft) / (SQRT[(134 – 33)2 + (454 – 325) 2 ] * 98.4251 ft) = 3093 ft / (163.835 * 98.4251 ft) = 3893 ft / 16125 ft = 0.1918 Height = (Tangent * Run) + Viewer Height = (0.1918 * (SQRT[(300 – 33)2 + (454 – 114) 2 ] * 98.4251 ft)) + 3219 ft = (0.1918 * 432.307 * 98.4251 ft) + 3219 = 11,380 Feet Viewer Location First Ridge (300c, 114r) Point of Interest + First Ridge Elevation (134c, 325r) 6,312 Feet Point of Interest Minimum Visible Elevation 11,380 Feet Seen N Viewer Elevation 3,219 Feet Not Seen . Viewer Location (33c, 454r) + 6 miles North  Viewshed at 0 feet rise 0 miles

  5. Visual Connectivity(500’ above the terrain) Point of Interest + …an animated series of “viewsheds” from increasing viewer heights demonstrates the importance of a 3-dimensional GIS …advance slides for 1000’ viewer height increases  First Ridge 6,312 Feet Seen 3,219 + 500 = 3,719 Feet N . Viewer Location + 6 miles North  Viewshed at 500 feet rise 0 miles

  6. Visual Connectivity(1000’ above the terrain) Point of Interest + Second Ridge Seen 3,219 + 1,000 = 4,219 Feet N Second Ridge Elevation (187c, 258r) 7,799 Feet . Viewer Location + 6 miles North  Viewshed at 1000 feet rise 0 miles

  7. Visual Connectivity(2000’ above the terrain) Point of Interest + Second Ridge 7,799 Feet Seen 3,219 + 2,000 = 5,219 Feet N . Viewer Location + 6 miles North  Viewshed at 2000 feet rise 0 miles

  8. Visual Connectivity(3000’ above the terrain) Point of Interest + Seen 3,219 + 3,000 = 6,219 Feet N Second Ridge 7,799 Feet . Viewer Location + 6 miles North  Viewshed at 3000 feet rise 0 miles

  9. Visual Connectivity(4000’ above the terrain) Point of Interest + Seen 3,219 + 4,000 = 7,219 Feet N Second Ridge 7,799 Feet . Viewer Location + 6 miles North  Viewshed at 4000 feet rise 0 miles

  10. Visual Connectivity(5000’ above the terrain) Point of Interest + Seen 3,219 + 5,000 = 8,219 Feet N Second Ridge 7,799 Feet . Viewer Location + 6 miles North  Viewshed at 5000 feet rise 0 miles

  11. Visual Connectivity(6000’ above the terrain) Point of Interest + Seen 3,219 + 6,000 = 9,219 Feet N Second Ridge 7,799 Feet . Viewer Location + 6 miles North  Viewshed at 6000 feet rise 0 miles

  12. Visual Connectivity(7000’ above the terrain) Point of Interest + Seen 3,219 + 7,000 = 10,219 Feet N Second Ridge 7,799 Feet . Viewer Location + 6 miles North  Viewshed at 7000 feet rise 0 miles

  13. Visual Connectivity(8000’ above the terrain) Point of Interest + Seen . 3,219 + 8,000 = 11,219 Feet N Second Ridge 7,799 Feet Viewer Location + 6 miles North  Viewshed at 8000 feet rise 0 miles

  14. Visual Connectivity(9000’ above the terrain) Point of Interest + . Seen 3,219 + 9,000 = 12,219 Feet N Second Ridge 7,799 Feet Viewer Location + 6 miles North  Viewshed at 9000 feet rise 0 miles

  15. Visual Connectivity(10000’ above the terrain) Point of Interest + . Seen 3,219 + 10,000 = 13,219 Feet N Second Ridge 7,799 Feet Viewer Location + 6 miles North  Viewshed at 10000 feet rise 0 miles

  16. Visual Connectivity(11000’ above the terrain) Tangent = 0, therefore POI surface location is seen Point of Interest + . 3,219 + 11,000 = 14,219 Feet N Second Ridge 7,799 Feet Surface Seen Viewer Location + 6 miles North  Viewshed at 11000 feet rise 0 miles

  17. Representing Geographic Space(2D and 3D) . 3-D Grid Data Structure is a direct expansion of the 2D structure with X, Y and Z coordinates defining the position in a 3-dimensional data matrix plus a value representing the characteristic or condition (attribute) associated with that location. Increasing Viewer Height (1000’ increments) Point of Interest Seen 12 times 12 3D Volume (Voxel) 3,219 + 11,000 = 14,219 Feet …from 0 Feet Viewer Height All volume locations are assigned a VE value Seen 1 Time 2D Plane (Pixel) Viewer Location 1 All surface locations are assigned a VE value Visual Exposure (VE) …a count of the number of times seen from specified viewer positions (0 – 11,000 feet above the terrain)

  18. Visual Connectivity(12000’ above the terrain) …continue advancing slides for viewsheds of viewer height increases to 20,000’ . N 3,219 + 12,000 = 15,219 Feet Viewer Location 6 miles North  Viewshed at 12000 feet rise 0 miles

  19. Visual Connectivity(13000’ above the terrain) . N 3,219 + 13,000 = 16,219 Feet Viewer Location 6 miles North  Viewshed at 13000 feet rise 0 miles

  20. Visual Connectivity(14000’ above the terrain) 3,219 + 14,000 = 17,219 Feet . N Viewer Location 6 miles North  Viewshed at 14000 feet rise 0 miles

  21. Visual Connectivity(15000’ above the terrain) . N 3,219 + 15,000 = 18,219 Feet Viewer Location 6 miles North  Viewshed at 15000 feet rise 0 miles

  22. Visual Connectivity(16000’ above the terrain) . 3,219 + 16,000 = 19,219 Feet N Viewer Location 6 miles North  Viewshed at 16000 feet rise 0 miles

  23. Visual Connectivity(17000’ above the terrain) . 3,219 + 17,000 = 20,219 Feet N Viewer Location 6 miles North  Viewshed at 17000 feet rise 0 miles

  24. Visual Connectivity(18000’ above the terrain) . 3,219 + 18,000 = 21,219 Feet N Viewer Location 6 miles North  Viewshed at 18000 feet rise 0 miles

  25. Visual Connectivity(19000’ above the terrain) . N 3,219 + 19,000 = 22,219 Feet Viewer Location 6 miles North  Viewshed at 19000 feet rise 0 miles

  26. Visual Connectivity(20000’ above the terrain) . N 3,219 + 20,000 = 23,219 Feet Viewer Location 6 miles North  Viewshed at 20000 feet rise 0 miles

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