lab 1: projection yingjie hu. what is a projection? a projection is the rendering of the earth’s...
TRANSCRIPT
![Page 1: Lab 1: Projection Yingjie Hu. What is a projection? A projection is the rendering of the earth’s round, three-dimensional surface onto a flat map. Projection](https://reader035.vdocument.in/reader035/viewer/2022062407/56649dc05503460f94ab41be/html5/thumbnails/1.jpg)
Lab 1: Projection
Yingjie Hu
![Page 2: Lab 1: Projection Yingjie Hu. What is a projection? A projection is the rendering of the earth’s round, three-dimensional surface onto a flat map. Projection](https://reader035.vdocument.in/reader035/viewer/2022062407/56649dc05503460f94ab41be/html5/thumbnails/2.jpg)
What is a projection?
• A projection is the rendering of the earth’s round, three-dimensional surface onto a flat map.
Projection
![Page 3: Lab 1: Projection Yingjie Hu. What is a projection? A projection is the rendering of the earth’s round, three-dimensional surface onto a flat map. Projection](https://reader035.vdocument.in/reader035/viewer/2022062407/56649dc05503460f94ab41be/html5/thumbnails/3.jpg)
What do we need to make a projection?
• A surface• A method to project the features of the earth
on our surface
![Page 4: Lab 1: Projection Yingjie Hu. What is a projection? A projection is the rendering of the earth’s round, three-dimensional surface onto a flat map. Projection](https://reader035.vdocument.in/reader035/viewer/2022062407/56649dc05503460f94ab41be/html5/thumbnails/4.jpg)
Surface
• Plane surface• Azimuthal projection (planar projection)
![Page 5: Lab 1: Projection Yingjie Hu. What is a projection? A projection is the rendering of the earth’s round, three-dimensional surface onto a flat map. Projection](https://reader035.vdocument.in/reader035/viewer/2022062407/56649dc05503460f94ab41be/html5/thumbnails/5.jpg)
Surface
• Cylinder • Cylindrical
![Page 6: Lab 1: Projection Yingjie Hu. What is a projection? A projection is the rendering of the earth’s round, three-dimensional surface onto a flat map. Projection](https://reader035.vdocument.in/reader035/viewer/2022062407/56649dc05503460f94ab41be/html5/thumbnails/6.jpg)
Surface
• Cone• Conic
![Page 7: Lab 1: Projection Yingjie Hu. What is a projection? A projection is the rendering of the earth’s round, three-dimensional surface onto a flat map. Projection](https://reader035.vdocument.in/reader035/viewer/2022062407/56649dc05503460f94ab41be/html5/thumbnails/7.jpg)
![Page 8: Lab 1: Projection Yingjie Hu. What is a projection? A projection is the rendering of the earth’s round, three-dimensional surface onto a flat map. Projection](https://reader035.vdocument.in/reader035/viewer/2022062407/56649dc05503460f94ab41be/html5/thumbnails/8.jpg)
How to project? Surface aspect
• Equatorial
![Page 9: Lab 1: Projection Yingjie Hu. What is a projection? A projection is the rendering of the earth’s round, three-dimensional surface onto a flat map. Projection](https://reader035.vdocument.in/reader035/viewer/2022062407/56649dc05503460f94ab41be/html5/thumbnails/9.jpg)
Surface aspect
• Transverse
![Page 10: Lab 1: Projection Yingjie Hu. What is a projection? A projection is the rendering of the earth’s round, three-dimensional surface onto a flat map. Projection](https://reader035.vdocument.in/reader035/viewer/2022062407/56649dc05503460f94ab41be/html5/thumbnails/10.jpg)
Surface aspect
• Oblique
![Page 11: Lab 1: Projection Yingjie Hu. What is a projection? A projection is the rendering of the earth’s round, three-dimensional surface onto a flat map. Projection](https://reader035.vdocument.in/reader035/viewer/2022062407/56649dc05503460f94ab41be/html5/thumbnails/11.jpg)
Surface aspect
• Polar
![Page 12: Lab 1: Projection Yingjie Hu. What is a projection? A projection is the rendering of the earth’s round, three-dimensional surface onto a flat map. Projection](https://reader035.vdocument.in/reader035/viewer/2022062407/56649dc05503460f94ab41be/html5/thumbnails/12.jpg)
Tangency
• Definition– Location at which the projection surface and the
globe touch.
![Page 13: Lab 1: Projection Yingjie Hu. What is a projection? A projection is the rendering of the earth’s round, three-dimensional surface onto a flat map. Projection](https://reader035.vdocument.in/reader035/viewer/2022062407/56649dc05503460f94ab41be/html5/thumbnails/13.jpg)
Secancy
• Definition– Location at which the projection surface cuts
through the globe
![Page 14: Lab 1: Projection Yingjie Hu. What is a projection? A projection is the rendering of the earth’s round, three-dimensional surface onto a flat map. Projection](https://reader035.vdocument.in/reader035/viewer/2022062407/56649dc05503460f94ab41be/html5/thumbnails/14.jpg)
Distortion
• The earth has a curved surface. When transforming the round globe to a flat surface, we will inevitably lose accuracy at places where the “paper” doesn’t touch the globe.
![Page 15: Lab 1: Projection Yingjie Hu. What is a projection? A projection is the rendering of the earth’s round, three-dimensional surface onto a flat map. Projection](https://reader035.vdocument.in/reader035/viewer/2022062407/56649dc05503460f94ab41be/html5/thumbnails/15.jpg)
Map properties
• Conformality (Conformal projection)– Retention of correct angles on a map– Retaining the shapes and directions of the
features on the earth– Lose the accuracy of area– Applied in navigation
![Page 16: Lab 1: Projection Yingjie Hu. What is a projection? A projection is the rendering of the earth’s round, three-dimensional surface onto a flat map. Projection](https://reader035.vdocument.in/reader035/viewer/2022062407/56649dc05503460f94ab41be/html5/thumbnails/16.jpg)
Map properties
• Equivalence (Equivalent projection)– Retention the accuracy of the area on a map– Lose shape and direction of the features on the
globe– Applied in area calculation
![Page 17: Lab 1: Projection Yingjie Hu. What is a projection? A projection is the rendering of the earth’s round, three-dimensional surface onto a flat map. Projection](https://reader035.vdocument.in/reader035/viewer/2022062407/56649dc05503460f94ab41be/html5/thumbnails/17.jpg)
Map properties
• Compromise projections– Neither conformal nor equivalent– Avoid extreme distortion of one map property
![Page 18: Lab 1: Projection Yingjie Hu. What is a projection? A projection is the rendering of the earth’s round, three-dimensional surface onto a flat map. Projection](https://reader035.vdocument.in/reader035/viewer/2022062407/56649dc05503460f94ab41be/html5/thumbnails/18.jpg)
Map properties
• Short summary– Distortion is inevitable, since the globe is round
while paper is flat.– Preserving one property (shape) results in the
distortion of another property (area).– Conformality retains shape and direction, but it
loses area accuracy. Equivalency has the opposite properties.
![Page 19: Lab 1: Projection Yingjie Hu. What is a projection? A projection is the rendering of the earth’s round, three-dimensional surface onto a flat map. Projection](https://reader035.vdocument.in/reader035/viewer/2022062407/56649dc05503460f94ab41be/html5/thumbnails/19.jpg)
How can we get the projection information from a map?
• Surface type– From the shapes constituted by longitudes and
latitudes
Cone
![Page 20: Lab 1: Projection Yingjie Hu. What is a projection? A projection is the rendering of the earth’s round, three-dimensional surface onto a flat map. Projection](https://reader035.vdocument.in/reader035/viewer/2022062407/56649dc05503460f94ab41be/html5/thumbnails/20.jpg)
How can we get the projection information from a map?
• Surface type– From the shapes constituted by longitudes and
latitudes
Cylinder
![Page 21: Lab 1: Projection Yingjie Hu. What is a projection? A projection is the rendering of the earth’s round, three-dimensional surface onto a flat map. Projection](https://reader035.vdocument.in/reader035/viewer/2022062407/56649dc05503460f94ab41be/html5/thumbnails/21.jpg)
How can we get the projection information from a map?
• Surface type– From the shapes constituted by longitudes and
latitudes
Plane
![Page 22: Lab 1: Projection Yingjie Hu. What is a projection? A projection is the rendering of the earth’s round, three-dimensional surface onto a flat map. Projection](https://reader035.vdocument.in/reader035/viewer/2022062407/56649dc05503460f94ab41be/html5/thumbnails/22.jpg)
How can we get the projection information from a map?
• Surface aspect– From the area focused by the map
Polar
![Page 23: Lab 1: Projection Yingjie Hu. What is a projection? A projection is the rendering of the earth’s round, three-dimensional surface onto a flat map. Projection](https://reader035.vdocument.in/reader035/viewer/2022062407/56649dc05503460f94ab41be/html5/thumbnails/23.jpg)
How can we get the projection information from a map?
• Surface aspect– From the area that has the least distortion.
Equatorial
![Page 24: Lab 1: Projection Yingjie Hu. What is a projection? A projection is the rendering of the earth’s round, three-dimensional surface onto a flat map. Projection](https://reader035.vdocument.in/reader035/viewer/2022062407/56649dc05503460f94ab41be/html5/thumbnails/24.jpg)
How can we get the projection information from a map?
• Surface aspect– From the area that has the least distortion.
Transverse
![Page 25: Lab 1: Projection Yingjie Hu. What is a projection? A projection is the rendering of the earth’s round, three-dimensional surface onto a flat map. Projection](https://reader035.vdocument.in/reader035/viewer/2022062407/56649dc05503460f94ab41be/html5/thumbnails/25.jpg)
How can we get the projection information from a map?
• Surface aspect– From the area that has the least distortion.
Oblique
![Page 26: Lab 1: Projection Yingjie Hu. What is a projection? A projection is the rendering of the earth’s round, three-dimensional surface onto a flat map. Projection](https://reader035.vdocument.in/reader035/viewer/2022062407/56649dc05503460f94ab41be/html5/thumbnails/26.jpg)
How can we get the projection information from a map?
• Conformality – The shape is preserved.– The area of the features is distorted.
![Page 27: Lab 1: Projection Yingjie Hu. What is a projection? A projection is the rendering of the earth’s round, three-dimensional surface onto a flat map. Projection](https://reader035.vdocument.in/reader035/viewer/2022062407/56649dc05503460f94ab41be/html5/thumbnails/27.jpg)
How can we get the projection information from a map?
• Equivalence– The area is preserved.– The shape of the continents is distorted.
![Page 28: Lab 1: Projection Yingjie Hu. What is a projection? A projection is the rendering of the earth’s round, three-dimensional surface onto a flat map. Projection](https://reader035.vdocument.in/reader035/viewer/2022062407/56649dc05503460f94ab41be/html5/thumbnails/28.jpg)
Assignment
• All the materials are on Gauchospace.• Answer all the questions, print your answer
sheet, and submit it in the next lab class.• Due date: Oct. 6th (Next Thursday).• Homework which is turned in late will lose
10% of the full score each weekday. Homework which is submitted after 5 weekdays will not be accepted.