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Mapping and Projections Web resources: Geographer’s Craft, Department of Geography, University of...
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![Page 1: Mapping and Projections Web resources: Geographer’s Craft, Department of Geography, University of Colorado at Boulder - particularly Peter H. Dana’s part.](https://reader031.fdocuments.net/reader031/viewer/2022013004/56649e795503460f94b798f5/html5/thumbnails/1.jpg)
Mapping and ProjectionsWeb resources:
Geographer’s Craft, Department of Geography, University of Colorado at Boulder - particularly Peter H.
Dana’s parthttp://www.colorado.edu/geography/gcraft/
contents.html
Laurie Garo, Map Projections module, in Virtual Geography Department, U. of Texas at Austin (hosted
at U. of Colorado)http://www.colorado.edu/geography/virtdept/
contents.html
![Page 2: Mapping and Projections Web resources: Geographer’s Craft, Department of Geography, University of Colorado at Boulder - particularly Peter H. Dana’s part.](https://reader031.fdocuments.net/reader031/viewer/2022013004/56649e795503460f94b798f5/html5/thumbnails/2.jpg)
Map Projections
•Basic problem:–Earth is round–Paper is flat
![Page 3: Mapping and Projections Web resources: Geographer’s Craft, Department of Geography, University of Colorado at Boulder - particularly Peter H. Dana’s part.](https://reader031.fdocuments.net/reader031/viewer/2022013004/56649e795503460f94b798f5/html5/thumbnails/3.jpg)
Conformal
![Page 4: Mapping and Projections Web resources: Geographer’s Craft, Department of Geography, University of Colorado at Boulder - particularly Peter H. Dana’s part.](https://reader031.fdocuments.net/reader031/viewer/2022013004/56649e795503460f94b798f5/html5/thumbnails/4.jpg)
Equivalent or Equal Area
![Page 5: Mapping and Projections Web resources: Geographer’s Craft, Department of Geography, University of Colorado at Boulder - particularly Peter H. Dana’s part.](https://reader031.fdocuments.net/reader031/viewer/2022013004/56649e795503460f94b798f5/html5/thumbnails/5.jpg)
Equidistant
![Page 6: Mapping and Projections Web resources: Geographer’s Craft, Department of Geography, University of Colorado at Boulder - particularly Peter H. Dana’s part.](https://reader031.fdocuments.net/reader031/viewer/2022013004/56649e795503460f94b798f5/html5/thumbnails/6.jpg)
Equidistant CylindricalMap from Carlo Futuri
![Page 7: Mapping and Projections Web resources: Geographer’s Craft, Department of Geography, University of Colorado at Boulder - particularly Peter H. Dana’s part.](https://reader031.fdocuments.net/reader031/viewer/2022013004/56649e795503460f94b798f5/html5/thumbnails/7.jpg)
Solving the Problem
• How do you represent a curved surface on a flat surface?– Bonehead way - just plot latitude
vs. longitude as cartesian rectangular coordinates
– Projection - fit a flat surface around (or through) a sphere, and trace the pertinent information on it
![Page 8: Mapping and Projections Web resources: Geographer’s Craft, Department of Geography, University of Colorado at Boulder - particularly Peter H. Dana’s part.](https://reader031.fdocuments.net/reader031/viewer/2022013004/56649e795503460f94b798f5/html5/thumbnails/8.jpg)
Unprojected map
![Page 9: Mapping and Projections Web resources: Geographer’s Craft, Department of Geography, University of Colorado at Boulder - particularly Peter H. Dana’s part.](https://reader031.fdocuments.net/reader031/viewer/2022013004/56649e795503460f94b798f5/html5/thumbnails/9.jpg)
Types of projections
• Three main families:– Cylindrical - wrap sheet of paper around
globe in cylinder shape• Also pseudocylindrical - like cylindrical but the
sheet of paper bends inward at the poles
– Conic - form sheet of paper into a cone and insert globe • Also polyconic - multiple cones
– Azimuthal - place flat sheet of paper next to globe; project features out onto it
![Page 10: Mapping and Projections Web resources: Geographer’s Craft, Department of Geography, University of Colorado at Boulder - particularly Peter H. Dana’s part.](https://reader031.fdocuments.net/reader031/viewer/2022013004/56649e795503460f94b798f5/html5/thumbnails/10.jpg)
Cylindrical Projection
![Page 11: Mapping and Projections Web resources: Geographer’s Craft, Department of Geography, University of Colorado at Boulder - particularly Peter H. Dana’s part.](https://reader031.fdocuments.net/reader031/viewer/2022013004/56649e795503460f94b798f5/html5/thumbnails/11.jpg)
Cylindrical Projection• Formed by wrapping a large, flat plane
around the globe to form a cylinder.
• Transfer latitude, longitude, shapes onto cylinder, then unfolded into a flat plane.
• Typically used to represent the entire world; often projected from center of globe with equator as tangent line
• Most types show parallels and meridians forming straight perpendicular lines.
![Page 12: Mapping and Projections Web resources: Geographer’s Craft, Department of Geography, University of Colorado at Boulder - particularly Peter H. Dana’s part.](https://reader031.fdocuments.net/reader031/viewer/2022013004/56649e795503460f94b798f5/html5/thumbnails/12.jpg)
Cylindrical Projection
![Page 13: Mapping and Projections Web resources: Geographer’s Craft, Department of Geography, University of Colorado at Boulder - particularly Peter H. Dana’s part.](https://reader031.fdocuments.net/reader031/viewer/2022013004/56649e795503460f94b798f5/html5/thumbnails/13.jpg)
Pseudocylindrical Projection
• Projection surface is not rectangular
• Instead, it curves inwards at the poles.
• Latitude lines are straight; central meridian is straight, but other meridians are curved (concave toward the central meridian).
• Often used for world maps
![Page 14: Mapping and Projections Web resources: Geographer’s Craft, Department of Geography, University of Colorado at Boulder - particularly Peter H. Dana’s part.](https://reader031.fdocuments.net/reader031/viewer/2022013004/56649e795503460f94b798f5/html5/thumbnails/14.jpg)
Pseudocylindrical Projection
![Page 15: Mapping and Projections Web resources: Geographer’s Craft, Department of Geography, University of Colorado at Boulder - particularly Peter H. Dana’s part.](https://reader031.fdocuments.net/reader031/viewer/2022013004/56649e795503460f94b798f5/html5/thumbnails/15.jpg)
Pseudocylindrical Projection
![Page 16: Mapping and Projections Web resources: Geographer’s Craft, Department of Geography, University of Colorado at Boulder - particularly Peter H. Dana’s part.](https://reader031.fdocuments.net/reader031/viewer/2022013004/56649e795503460f94b798f5/html5/thumbnails/16.jpg)
Pseudocylindrical Projection
![Page 17: Mapping and Projections Web resources: Geographer’s Craft, Department of Geography, University of Colorado at Boulder - particularly Peter H. Dana’s part.](https://reader031.fdocuments.net/reader031/viewer/2022013004/56649e795503460f94b798f5/html5/thumbnails/17.jpg)
Conic Projection
![Page 18: Mapping and Projections Web resources: Geographer’s Craft, Department of Geography, University of Colorado at Boulder - particularly Peter H. Dana’s part.](https://reader031.fdocuments.net/reader031/viewer/2022013004/56649e795503460f94b798f5/html5/thumbnails/18.jpg)
Conic Projection
• Points from the globe are transferred to a cone fit around the sphere.
• Usually, the pointy end of the cone is directly over the north or south pole, but you can do it anywhere.
• Can represent both hemispheres, but distortion increases the farther along the cone you go
![Page 19: Mapping and Projections Web resources: Geographer’s Craft, Department of Geography, University of Colorado at Boulder - particularly Peter H. Dana’s part.](https://reader031.fdocuments.net/reader031/viewer/2022013004/56649e795503460f94b798f5/html5/thumbnails/19.jpg)
Conic Projection• Often used to project areas that
have a greater east-west extent than north-south, e.g., the United States.
• When projected from the center of the globe, conic projections typically show parallels forming arcs concave toward the North or South pole, and meridians are either straight or curved and radiate outwards from the direction of the point of the cone.
![Page 20: Mapping and Projections Web resources: Geographer’s Craft, Department of Geography, University of Colorado at Boulder - particularly Peter H. Dana’s part.](https://reader031.fdocuments.net/reader031/viewer/2022013004/56649e795503460f94b798f5/html5/thumbnails/20.jpg)
Conic Projection
![Page 21: Mapping and Projections Web resources: Geographer’s Craft, Department of Geography, University of Colorado at Boulder - particularly Peter H. Dana’s part.](https://reader031.fdocuments.net/reader031/viewer/2022013004/56649e795503460f94b798f5/html5/thumbnails/21.jpg)
Equidistant Conic Projection
![Page 22: Mapping and Projections Web resources: Geographer’s Craft, Department of Geography, University of Colorado at Boulder - particularly Peter H. Dana’s part.](https://reader031.fdocuments.net/reader031/viewer/2022013004/56649e795503460f94b798f5/html5/thumbnails/22.jpg)
Albers Equal Area Conic
![Page 23: Mapping and Projections Web resources: Geographer’s Craft, Department of Geography, University of Colorado at Boulder - particularly Peter H. Dana’s part.](https://reader031.fdocuments.net/reader031/viewer/2022013004/56649e795503460f94b798f5/html5/thumbnails/23.jpg)
Polyconic Projection
• Complex projection, used originally by USGS for quadrangle maps of U.S.
• Uses an infinite number of cones applied to an infinite number of tangents across a given hemisphere
• Reduces distortion, but harder to conceptualize and produce
![Page 24: Mapping and Projections Web resources: Geographer’s Craft, Department of Geography, University of Colorado at Boulder - particularly Peter H. Dana’s part.](https://reader031.fdocuments.net/reader031/viewer/2022013004/56649e795503460f94b798f5/html5/thumbnails/24.jpg)
Polyconic Projection
![Page 25: Mapping and Projections Web resources: Geographer’s Craft, Department of Geography, University of Colorado at Boulder - particularly Peter H. Dana’s part.](https://reader031.fdocuments.net/reader031/viewer/2022013004/56649e795503460f94b798f5/html5/thumbnails/25.jpg)
Polyconic Projection(centered at equator, 90ºW)
![Page 26: Mapping and Projections Web resources: Geographer’s Craft, Department of Geography, University of Colorado at Boulder - particularly Peter H. Dana’s part.](https://reader031.fdocuments.net/reader031/viewer/2022013004/56649e795503460f94b798f5/html5/thumbnails/26.jpg)
Azimuthal (Planar) Projection
![Page 27: Mapping and Projections Web resources: Geographer’s Craft, Department of Geography, University of Colorado at Boulder - particularly Peter H. Dana’s part.](https://reader031.fdocuments.net/reader031/viewer/2022013004/56649e795503460f94b798f5/html5/thumbnails/27.jpg)
Azimuthal or Planar Projection
• Globe grid is projected onto a flat plane
• Plane is normally placed above the north or south pole, so normally only one hemisphere, or a portion of it, is represented
• When projected from the center of the globe, a typical polar azimuthal projection shows circular latitude lines with radiating longitude lines
![Page 28: Mapping and Projections Web resources: Geographer’s Craft, Department of Geography, University of Colorado at Boulder - particularly Peter H. Dana’s part.](https://reader031.fdocuments.net/reader031/viewer/2022013004/56649e795503460f94b798f5/html5/thumbnails/28.jpg)
Azimuthal Projection
![Page 29: Mapping and Projections Web resources: Geographer’s Craft, Department of Geography, University of Colorado at Boulder - particularly Peter H. Dana’s part.](https://reader031.fdocuments.net/reader031/viewer/2022013004/56649e795503460f94b798f5/html5/thumbnails/29.jpg)
Azimuthal Projection
![Page 30: Mapping and Projections Web resources: Geographer’s Craft, Department of Geography, University of Colorado at Boulder - particularly Peter H. Dana’s part.](https://reader031.fdocuments.net/reader031/viewer/2022013004/56649e795503460f94b798f5/html5/thumbnails/30.jpg)
Oblique Azimuthal Projection
Orthographic sort of means viewed from
infinite distance
![Page 31: Mapping and Projections Web resources: Geographer’s Craft, Department of Geography, University of Colorado at Boulder - particularly Peter H. Dana’s part.](https://reader031.fdocuments.net/reader031/viewer/2022013004/56649e795503460f94b798f5/html5/thumbnails/31.jpg)
Types of projections
• Tangent– Flat surface only touches globe along one
circular line (or at one point for Azimuthal)
• Secant– Flat surface passes through globe; touches
surface at two circular lines (or in one circle for Azimuthal)
– Some projection is inward rather than outward
– Reduces distortion of large areas
![Page 32: Mapping and Projections Web resources: Geographer’s Craft, Department of Geography, University of Colorado at Boulder - particularly Peter H. Dana’s part.](https://reader031.fdocuments.net/reader031/viewer/2022013004/56649e795503460f94b798f5/html5/thumbnails/32.jpg)
Tangent Projection
![Page 33: Mapping and Projections Web resources: Geographer’s Craft, Department of Geography, University of Colorado at Boulder - particularly Peter H. Dana’s part.](https://reader031.fdocuments.net/reader031/viewer/2022013004/56649e795503460f94b798f5/html5/thumbnails/33.jpg)
Secant Projection
![Page 34: Mapping and Projections Web resources: Geographer’s Craft, Department of Geography, University of Colorado at Boulder - particularly Peter H. Dana’s part.](https://reader031.fdocuments.net/reader031/viewer/2022013004/56649e795503460f94b798f5/html5/thumbnails/34.jpg)
Secant Projection
![Page 35: Mapping and Projections Web resources: Geographer’s Craft, Department of Geography, University of Colorado at Boulder - particularly Peter H. Dana’s part.](https://reader031.fdocuments.net/reader031/viewer/2022013004/56649e795503460f94b798f5/html5/thumbnails/35.jpg)
Robinson Projection
![Page 36: Mapping and Projections Web resources: Geographer’s Craft, Department of Geography, University of Colorado at Boulder - particularly Peter H. Dana’s part.](https://reader031.fdocuments.net/reader031/viewer/2022013004/56649e795503460f94b798f5/html5/thumbnails/36.jpg)
Goode’s Interrupted Homolosine Projection
![Page 37: Mapping and Projections Web resources: Geographer’s Craft, Department of Geography, University of Colorado at Boulder - particularly Peter H. Dana’s part.](https://reader031.fdocuments.net/reader031/viewer/2022013004/56649e795503460f94b798f5/html5/thumbnails/37.jpg)
Tissot indicators
• Tissot’s idea - to see the effects of distortion, show what shape small circles on the surface of the globe take after projection
• This shows shape, scale, area, and other distortions
![Page 38: Mapping and Projections Web resources: Geographer’s Craft, Department of Geography, University of Colorado at Boulder - particularly Peter H. Dana’s part.](https://reader031.fdocuments.net/reader031/viewer/2022013004/56649e795503460f94b798f5/html5/thumbnails/38.jpg)
Tissot Indicators – Mercator (Conformal)
Image from http://quantdec.com/tissot
![Page 39: Mapping and Projections Web resources: Geographer’s Craft, Department of Geography, University of Colorado at Boulder - particularly Peter H. Dana’s part.](https://reader031.fdocuments.net/reader031/viewer/2022013004/56649e795503460f94b798f5/html5/thumbnails/39.jpg)
Tissot Indicators – Peters Equal Area
Image from http://quantdec.com/tissot
![Page 40: Mapping and Projections Web resources: Geographer’s Craft, Department of Geography, University of Colorado at Boulder - particularly Peter H. Dana’s part.](https://reader031.fdocuments.net/reader031/viewer/2022013004/56649e795503460f94b798f5/html5/thumbnails/40.jpg)
Tissot Indicators – Azimuthal Equidistant
Image from http://quantdec.com/tissot
![Page 41: Mapping and Projections Web resources: Geographer’s Craft, Department of Geography, University of Colorado at Boulder - particularly Peter H. Dana’s part.](https://reader031.fdocuments.net/reader031/viewer/2022013004/56649e795503460f94b798f5/html5/thumbnails/41.jpg)
Tissot Indicators
![Page 42: Mapping and Projections Web resources: Geographer’s Craft, Department of Geography, University of Colorado at Boulder - particularly Peter H. Dana’s part.](https://reader031.fdocuments.net/reader031/viewer/2022013004/56649e795503460f94b798f5/html5/thumbnails/42.jpg)
Silly Projections
![Page 43: Mapping and Projections Web resources: Geographer’s Craft, Department of Geography, University of Colorado at Boulder - particularly Peter H. Dana’s part.](https://reader031.fdocuments.net/reader031/viewer/2022013004/56649e795503460f94b798f5/html5/thumbnails/43.jpg)
Web sites to visit:
• http://www.guilford.edu/geology/Geo340.html