1 Practical Vector GIS Globe to map 2 The where is it… How do we locate Syracuse in space on the...
-
Upload
beryl-cannon -
Category
Documents
-
view
219 -
download
0
Transcript of 1 Practical Vector GIS Globe to map 2 The where is it… How do we locate Syracuse in space on the...
![Page 1: 1 Practical Vector GIS Globe to map 2 The where is it… How do we locate Syracuse in space on the earth’s surface? On a FLAT surface?](https://reader033.fdocuments.us/reader033/viewer/2022051622/5697c0211a28abf838cd2fc8/html5/thumbnails/1.jpg)
1
Practical Vector GIS
Globe to map
![Page 2: 1 Practical Vector GIS Globe to map 2 The where is it… How do we locate Syracuse in space on the earth’s surface? On a FLAT surface?](https://reader033.fdocuments.us/reader033/viewer/2022051622/5697c0211a28abf838cd2fc8/html5/thumbnails/2.jpg)
2
The where is it…
• How do we locate Syracuse in space on the earth’s surface?
• On a FLAT surface?
![Page 3: 1 Practical Vector GIS Globe to map 2 The where is it… How do we locate Syracuse in space on the earth’s surface? On a FLAT surface?](https://reader033.fdocuments.us/reader033/viewer/2022051622/5697c0211a28abf838cd2fc8/html5/thumbnails/3.jpg)
3
The where is it…
• How do we locate Syracuse in space on the earth’s surface?
• On a FLAT surface?
![Page 4: 1 Practical Vector GIS Globe to map 2 The where is it… How do we locate Syracuse in space on the earth’s surface? On a FLAT surface?](https://reader033.fdocuments.us/reader033/viewer/2022051622/5697c0211a28abf838cd2fc8/html5/thumbnails/4.jpg)
4
Syracuse
-76.19 W 43.07N
How do we locate Syracuse on earth?
-76.19 degrees west of meridian through Greenwich, England
43.07 degrees N of the equator
![Page 5: 1 Practical Vector GIS Globe to map 2 The where is it… How do we locate Syracuse in space on the earth’s surface? On a FLAT surface?](https://reader033.fdocuments.us/reader033/viewer/2022051622/5697c0211a28abf838cd2fc8/html5/thumbnails/5.jpg)
5
-76.19 degrees west of meridian through Greenwich, England
43.07 degrees N of the equator
![Page 6: 1 Practical Vector GIS Globe to map 2 The where is it… How do we locate Syracuse in space on the earth’s surface? On a FLAT surface?](https://reader033.fdocuments.us/reader033/viewer/2022051622/5697c0211a28abf838cd2fc8/html5/thumbnails/6.jpg)
6
Earth’s Coordinate SystemX is Longitude and is measured E and W from Greenwich, England. West is negative, East is positiveY is latitude and is measured N and S from the equator. North is positive and S is negative.
These are called Geographic Coordinates
North Pole
South Pole
Lat = 0º
Lat = -30º
Long = -6 0º
Lat = 30º
![Page 7: 1 Practical Vector GIS Globe to map 2 The where is it… How do we locate Syracuse in space on the earth’s surface? On a FLAT surface?](https://reader033.fdocuments.us/reader033/viewer/2022051622/5697c0211a28abf838cd2fc8/html5/thumbnails/7.jpg)
7
Coordinates on EarthNorth Pole
South Pole
Latitude
Longitude
Equator
Meridians
Parallels
![Page 8: 1 Practical Vector GIS Globe to map 2 The where is it… How do we locate Syracuse in space on the earth’s surface? On a FLAT surface?](https://reader033.fdocuments.us/reader033/viewer/2022051622/5697c0211a28abf838cd2fc8/html5/thumbnails/8.jpg)
8
X, Y = Longitude, Latitude
Lines of constant LongitudeLines of constant Latitude
0-90 +90-180 +180
0
-30
30
-90
90
-60
60
Equator
Stretch the top
Stretch the bottom
![Page 9: 1 Practical Vector GIS Globe to map 2 The where is it… How do we locate Syracuse in space on the earth’s surface? On a FLAT surface?](https://reader033.fdocuments.us/reader033/viewer/2022051622/5697c0211a28abf838cd2fc8/html5/thumbnails/9.jpg)
9
X, Y = Longitude, Latitude
Lines of constant LongitudeLines of constant Latitude
0-90 +90-180 +180
0
-30
30
-90
90
-60
60
Equator
90E, 30N
90W, 30S
+90, +30
-90 -30
W76.15° N43.04°
-76.12° 43.08°
![Page 10: 1 Practical Vector GIS Globe to map 2 The where is it… How do we locate Syracuse in space on the earth’s surface? On a FLAT surface?](https://reader033.fdocuments.us/reader033/viewer/2022051622/5697c0211a28abf838cd2fc8/html5/thumbnails/10.jpg)
10
The world in Geographic Coordinates
IsAntarcticaReally that
big?
![Page 11: 1 Practical Vector GIS Globe to map 2 The where is it… How do we locate Syracuse in space on the earth’s surface? On a FLAT surface?](https://reader033.fdocuments.us/reader033/viewer/2022051622/5697c0211a28abf838cd2fc8/html5/thumbnails/11.jpg)
11
The where is it…
• How do we locate Syracuse in space on the earth’s surface?
• On a FLAT surface?
![Page 12: 1 Practical Vector GIS Globe to map 2 The where is it… How do we locate Syracuse in space on the earth’s surface? On a FLAT surface?](https://reader033.fdocuments.us/reader033/viewer/2022051622/5697c0211a28abf838cd2fc8/html5/thumbnails/12.jpg)
12
The where is it…
• How do we locate Syracuse in space on the earth’s surface?
• On a FLAT surface?
• What we just did, plot Long, Lat coordinates, put the globe on a flat surface but DISTORTION
• Why distorted?
![Page 13: 1 Practical Vector GIS Globe to map 2 The where is it… How do we locate Syracuse in space on the earth’s surface? On a FLAT surface?](https://reader033.fdocuments.us/reader033/viewer/2022051622/5697c0211a28abf838cd2fc8/html5/thumbnails/13.jpg)
13
![Page 14: 1 Practical Vector GIS Globe to map 2 The where is it… How do we locate Syracuse in space on the earth’s surface? On a FLAT surface?](https://reader033.fdocuments.us/reader033/viewer/2022051622/5697c0211a28abf838cd2fc8/html5/thumbnails/14.jpg)
14
![Page 15: 1 Practical Vector GIS Globe to map 2 The where is it… How do we locate Syracuse in space on the earth’s surface? On a FLAT surface?](https://reader033.fdocuments.us/reader033/viewer/2022051622/5697c0211a28abf838cd2fc8/html5/thumbnails/15.jpg)
15
![Page 16: 1 Practical Vector GIS Globe to map 2 The where is it… How do we locate Syracuse in space on the earth’s surface? On a FLAT surface?](https://reader033.fdocuments.us/reader033/viewer/2022051622/5697c0211a28abf838cd2fc8/html5/thumbnails/16.jpg)
16
![Page 17: 1 Practical Vector GIS Globe to map 2 The where is it… How do we locate Syracuse in space on the earth’s surface? On a FLAT surface?](https://reader033.fdocuments.us/reader033/viewer/2022051622/5697c0211a28abf838cd2fc8/html5/thumbnails/17.jpg)
17
Maps are Flat
• The globe is an ideal model of the earth (almost)
• But you can’t put a useful one in your pocket usless
• So the problem is to put data from a sphere (almost) onto a flat surface
• Xerox can’t do it
![Page 18: 1 Practical Vector GIS Globe to map 2 The where is it… How do we locate Syracuse in space on the earth’s surface? On a FLAT surface?](https://reader033.fdocuments.us/reader033/viewer/2022051622/5697c0211a28abf838cd2fc8/html5/thumbnails/18.jpg)
18
Overview
1. There are a number of problems that apply when converting to flat maps
• Geographic coordinate systems• #1 problem – Datums• #2 problem – Projection• #3 problem – Scale• #4 problem – Generalization
2. Here they are, 1 by 1
![Page 19: 1 Practical Vector GIS Globe to map 2 The where is it… How do we locate Syracuse in space on the earth’s surface? On a FLAT surface?](https://reader033.fdocuments.us/reader033/viewer/2022051622/5697c0211a28abf838cd2fc8/html5/thumbnails/19.jpg)
19
Problem #1, Datums
• Earth is NOT a sphere!• It is more pear shaped• To accommodate this geographers and
surveyors have created models of the earth’s surface
• These are called Datums• And this is booby trap #1 because…• Different shapes different coordinates
![Page 20: 1 Practical Vector GIS Globe to map 2 The where is it… How do we locate Syracuse in space on the earth’s surface? On a FLAT surface?](https://reader033.fdocuments.us/reader033/viewer/2022051622/5697c0211a28abf838cd2fc8/html5/thumbnails/20.jpg)
20
Trees Don’t Move Much• But their coordinates
can change• The Long/Lat of this
tree will be different depending on which datum is being used!
• Could be up to ~50m different in the US
• There are lots of different datums to contend with!
![Page 21: 1 Practical Vector GIS Globe to map 2 The where is it… How do we locate Syracuse in space on the earth’s surface? On a FLAT surface?](https://reader033.fdocuments.us/reader033/viewer/2022051622/5697c0211a28abf838cd2fc8/html5/thumbnails/21.jpg)
21
Problem #2
![Page 22: 1 Practical Vector GIS Globe to map 2 The where is it… How do we locate Syracuse in space on the earth’s surface? On a FLAT surface?](https://reader033.fdocuments.us/reader033/viewer/2022051622/5697c0211a28abf838cd2fc8/html5/thumbnails/22.jpg)
22
Mercator
![Page 23: 1 Practical Vector GIS Globe to map 2 The where is it… How do we locate Syracuse in space on the earth’s surface? On a FLAT surface?](https://reader033.fdocuments.us/reader033/viewer/2022051622/5697c0211a28abf838cd2fc8/html5/thumbnails/23.jpg)
23
The Projection Problem
• There are many mathematical ways of projecting the spherical surface onto a flat surface.
• For the earth these have names likeMercator
AlbersPolyconic
Lambert equal area Azimuthal
Peters
Albers equal area
![Page 24: 1 Practical Vector GIS Globe to map 2 The where is it… How do we locate Syracuse in space on the earth’s surface? On a FLAT surface?](https://reader033.fdocuments.us/reader033/viewer/2022051622/5697c0211a28abf838cd2fc8/html5/thumbnails/24.jpg)
24
Other Projections
Wrong Question – they are all right, just different.
And they all have different properties
![Page 25: 1 Practical Vector GIS Globe to map 2 The where is it… How do we locate Syracuse in space on the earth’s surface? On a FLAT surface?](https://reader033.fdocuments.us/reader033/viewer/2022051622/5697c0211a28abf838cd2fc8/html5/thumbnails/25.jpg)
25
Problem #3
GeographiGeographic SCALEc SCALE
![Page 26: 1 Practical Vector GIS Globe to map 2 The where is it… How do we locate Syracuse in space on the earth’s surface? On a FLAT surface?](https://reader033.fdocuments.us/reader033/viewer/2022051622/5697c0211a28abf838cd2fc8/html5/thumbnails/26.jpg)
26
DefinitionScale =
distance on map(distance unit)distance on ground (distance unit)
A Scale of 1/24,000 means
1 inch (or foot, or furlong) on the map =
24,000 inches (or feet or furlongs) on the ground.
![Page 27: 1 Practical Vector GIS Globe to map 2 The where is it… How do we locate Syracuse in space on the earth’s surface? On a FLAT surface?](https://reader033.fdocuments.us/reader033/viewer/2022051622/5697c0211a28abf838cd2fc8/html5/thumbnails/27.jpg)
27
2,600 Mi
3.5”
Numeric or Ratio scale =1/47,067,429
![Page 28: 1 Practical Vector GIS Globe to map 2 The where is it… How do we locate Syracuse in space on the earth’s surface? On a FLAT surface?](https://reader033.fdocuments.us/reader033/viewer/2022051622/5697c0211a28abf838cd2fc8/html5/thumbnails/28.jpg)
28
Living Room
Kitchen
Dining Room
2.6” / 25’
Scale = 1/115
![Page 29: 1 Practical Vector GIS Globe to map 2 The where is it… How do we locate Syracuse in space on the earth’s surface? On a FLAT surface?](https://reader033.fdocuments.us/reader033/viewer/2022051622/5697c0211a28abf838cd2fc8/html5/thumbnails/29.jpg)
29
Living Room
Kitchen
Dinning Rm.
Scale1/47,000,000
1/46,000
1/115
Is a smaller number than
Is a smaller number than
=0.000000021
=0.000022
=0.008696
Small Scale dataLarge
area/sheetLeast
accurate
Large Scale data
Small area / sheetMost
accurate
![Page 30: 1 Practical Vector GIS Globe to map 2 The where is it… How do we locate Syracuse in space on the earth’s surface? On a FLAT surface?](https://reader033.fdocuments.us/reader033/viewer/2022051622/5697c0211a28abf838cd2fc8/html5/thumbnails/30.jpg)
30
Living Room
Kitchen
Dinning Rm.
Scale1/47,000,000
1/46,000
1/115
Is a smaller number than
Is a smaller number than
=0.000000021
=0.000022
=0.008696
Small Scale dataLarge
area/sheetLeast
accurate
Large Scale data
Small area / sheetMost
accurate
8888
![Page 31: 1 Practical Vector GIS Globe to map 2 The where is it… How do we locate Syracuse in space on the earth’s surface? On a FLAT surface?](https://reader033.fdocuments.us/reader033/viewer/2022051622/5697c0211a28abf838cd2fc8/html5/thumbnails/31.jpg)
31
Problem #4 -Accuracy & Generalization
• When a paper map is made at a very small scale the cartographer is limited by the pen being used
• Can’t draw anything finer than the width of the pen line.
• At a scale of 1/1,000,000 a line 0.05 cm wide = 0.05x1,000,000 cm or 50,000 cm or 500 meters or 19,850” or 1,640’ wide!
• What road is 1,640’ wide!!!• So on the map the road is much, much too
wide
![Page 32: 1 Practical Vector GIS Globe to map 2 The where is it… How do we locate Syracuse in space on the earth’s surface? On a FLAT surface?](https://reader033.fdocuments.us/reader033/viewer/2022051622/5697c0211a28abf838cd2fc8/html5/thumbnails/32.jpg)
32
Accuracy & Generalization
• Take the case of a winding stream
• Shrink it to a Smaller scale (large area, small paper
• Now it is hard to see what is there
• So the cartographer simplifies the stream
![Page 33: 1 Practical Vector GIS Globe to map 2 The where is it… How do we locate Syracuse in space on the earth’s surface? On a FLAT surface?](https://reader033.fdocuments.us/reader033/viewer/2022051622/5697c0211a28abf838cd2fc8/html5/thumbnails/33.jpg)
33
Accuracy & Generalization
• The generalized stream is not as accurate a representation of the stream as the original
• And if you try to mix data of different scale common lines are NOT going to match
Original
Generalized
![Page 34: 1 Practical Vector GIS Globe to map 2 The where is it… How do we locate Syracuse in space on the earth’s surface? On a FLAT surface?](https://reader033.fdocuments.us/reader033/viewer/2022051622/5697c0211a28abf838cd2fc8/html5/thumbnails/34.jpg)
34
Booby Trap Summary
• Using a GIS is more than just combining various data layers – just knowing what buttons to push is NOT sufficient!!!
• You have to be careful that the basic 4 booby traps outlined above do not cause problems
• And 4 possible sources of error give Murphy a field day since problems encountered go up as n2
![Page 35: 1 Practical Vector GIS Globe to map 2 The where is it… How do we locate Syracuse in space on the earth’s surface? On a FLAT surface?](https://reader033.fdocuments.us/reader033/viewer/2022051622/5697c0211a28abf838cd2fc8/html5/thumbnails/35.jpg)
35
Booby Trap Summary
• Using a GIS is more than just combining various data layers
• You have to be careful that the basic three booby traps outlined here do not cause problems
• And 3 possible sources of error give Murphy a field day since problems encountered go up as n2
•Datum
•Projection
•Scale
•Generalization
![Page 36: 1 Practical Vector GIS Globe to map 2 The where is it… How do we locate Syracuse in space on the earth’s surface? On a FLAT surface?](https://reader033.fdocuments.us/reader033/viewer/2022051622/5697c0211a28abf838cd2fc8/html5/thumbnails/36.jpg)
36
icebergAnd that was
just this!
This topic will be a major part of the course!