1. Georeferencing with Paper Maps
Map Basics
How to Georeferencing with Paper Maps
Latitude and Longitude Mathematically
Error Calculator
(pay attention, you are doing this next!)

2. Pros and Cons of Paper Maps
Necessary for certain localities, such as distances by road and topographic features, especially when GIS layers are not readily available
Extents more readily obtained
Old paper maps may be the only option for obtaining coordinates for historic localities
Cons
Time-consuming
Good quality paper maps may be hard to find
Map printing errors

3. Map of Canada’s Wonderland, N of Toronto, Canada3

5. Map Basics Projection Map Anatomy: Citing Map as Georeferencing Source
Scale
Graticule
Datum
Citing Map as Georeferencing Source

6. Which compromise is right for the map?
Projection
Map projection is about rendering 3D into 2D.
Map projection is about compromises in order to preserve either area, linear distance or shape. 
Which compromise is right for the map?

7. Projection Geographic Mercator preserves NS distance
preserves shape (terrible for poles, distorts area)

8. Projection Winkel Tripel (NGS solution)
reduced distortion in both area and distance

9. Projection “Butterfly” map – Cahill 1909 emphasis on symmetry
preserves area, shape
contiguous land masses

10. Projection: Regional
Squat California (Geographic) vs. Equal-Area California (Teale Albers)

11. The Paper Map

12. Map Anatomy: Map Scale
Header

13. Map Anatomy: Map Scale
Usually recorded as a ratio, such as 1:100,000, or a fraction, such as 1/100:000
“Large scale” (Fine scale) maps, such as 1/10,000, show finer detail, less area
“Small scale” (Broad scale) maps, such as 1/500,000, show less detail, greater area
Think of “large” & “small” scale as the value of 1 in the fraction.
Example 1/10,000 > 1/500,000

14. Map Anatomy: Map Scale 1:25,000 Large Scale
Tofino
tof 14

15. Map Anatomy: Map Scale 1:250,000 Smaller Scale15

16. Map Anatomy: Map Scale 1:500,000 Smaller than before

17. Map Anatomy: Map Scale 1:1,000,000 Small Scale smaller than before17

18. Map Anatomy: Grid

19. Map with no grid labeled
Map Anatomy: Grid
Map with no grid labeled

20. Map Anatomy: Grid
Shows the placement of the parallels and meridians on maps
Used to determine latitude and longitude
Maps with graticule cannot be used to determine coordinates – only to determine extents
Can have more than one grid system in place (e.g., easting and northings for UTM and latitude and longitude)

21. Universal Transverse Mercator

22. The Grid/ Graticule
UTM
Northings
Add slide UTMs
UTM
Eastings

23. Map with no grid labeled
Map Anatomy: Datum
Map with no grid labeled

24. Map Anatomy: Datum
If datum is recorded, usually found near the map scale or publisher’s name
Use Horizontal Datum, not Vertical
Occasionally, if no datum is recorded but the reference ellipsoid is, then one can determine the datum using the pdf document found at (Use Appendix B)

25. Determining Coordinates from Paper Maps: Georeferencing Source
For Georeferencing Sources be sure to include the following:
Publisher name
Map Date
Map Scale
Map name
Example: USGS 15’ Topographic Series Boone 1956 or
USGS Topoquad 1:24000 Key West 1962

26. Determining Coordinates from Paper Maps
Paper maps are necessary when gazetteers will not report needed coordinates
Especially useful for distances by roads and topographic features like rivers and mountain ranges
Pay special attention to the grid lines and the hemisphere (latitudes in the southern hemisphere are negative, and longitudes in the western hemisphere are negative) when reporting in decimal degrees

27. Coordinate Integers for Hemispheres

28. Determining Coordinates from Paper Maps
Nauru Island, Pacific Islands Geographic
Society, :12,000

29. Determining Coordinates from Paper Maps: Latitude

30. Determining Coordinates from Paper Maps: Latitude

31. Determining Coordinates from Paper Maps: Longitude

32. Determining Coordinates from Paper Maps: Longitude

33. Determining Coordinate Precision
Determining Coordinate Precision for the Georeferencing Calculator:
The smallest measurement using our rulers is 1 mm ( = 0.1 cm), therefore we need to convert millimeters to minutes:
0.1 cm x (2 minutes/14 cm) = min
Choose the next largest fraction of a minute on the calculator.
For minutes, select 0.1 minutes.

34. Determining Coordinates from Paper Maps: Error Calculation

35. In Conclusion
Pay attention to whether you should add or subtract the offsets to the grid points
Measure from the center of your feature to the edge for extent
Plot your coordinates to double check your work
Explain any decisions you had to make in the GeoreferenceRemark field
Explain any errors in the locality description in the LocalityErrors field

36. Round up to 0.1 minute precision
For Georeferencing Source be sure to include the following:
Publisher name
Map Date
Map Scale
Map name
Example: United States Geological Society (USGS) Topographic Map California, 1956, map scale 1:24,000, map name “Boone”
Determining Lat and Long:
Determining Coordinate Precision:
0.1 cm x (2 minutes/14 cm) = min
Round up to 0.1 minute precision

37. Determining Coordinates Using the Error Calculator
Find a set of coordinates on the map from which lat and long increase. This is your “starting point”
Measure orthogonal offsets from these coordinates
Use calculator to determine “end point” coordinates
Use the calculator a second time for the error calculation
Latitude Increases
Longitude Increases

38. Measuring Orthogonal Offsets from Grid Coordinates
Measure distance south of latitude grid line.
Measure distance east of longitude grid line.

39. Determining Coordinates

40. Determining Coordinates

41. Error Calculation