# Georeferencing with Paper Maps

## Presentation on theme: "Georeferencing with Paper Maps"— Presentation transcript:

Georeferencing with Paper Maps
Museum of Vertebrate Zoology University of California, Berkeley & Royal Ontario Museum, Toronto

Overview Map Anatomy Georeferencing with Paper Maps Scale Grid Datum
Publisher Georeferencing with Paper Maps Latitude and Longitude Mathematically Error Calculator

Pros and Cons of Paper Maps
Pros 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 of Paper Maps Time-consuming Good quality paper maps may be hard to find Map printing errors

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Map Anatomy: Map Scale

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

Map Anatomy: Map Scale 1:25,000 Large Scale
Tofino tof 7

Map Anatomy: Map Scale 1:250,000 Smaller Scale
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Map Anatomy: Map Scale 1:500,000 Smaller than before

Map Anatomy: Map Scale 1:1,000,000 Small Scale smaller than before
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Map Anatomy: Grid

Map Anatomy: Grid Shows the placement of the parallels and meridians on maps Used to determine latitude and longitude Maps with no grid recorded cannot be used to determine coordinates – only to determine extents

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

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

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)

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: United States Geological Society (USGS) Topographic Map California, 1956, map scale 1:24,000, map name “Boone”

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)

Coordinate Integers for Hemispheres

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

Determining Coordinates from Paper Maps: Latitude

Determining Coordinates from Paper Maps: Latitude

Determining Coordinates from Paper Maps: Longitude

Determining Coordinates from Paper Maps: Longitude

Determining Coordinate Precision
Determining Coordinate Precision for the Georeferencing Calculator: The smallest measurement using our rulers is 1 mm ( = 0.01 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.

Determining Coordinates from Paper Maps: Error Calculation

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

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

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