Georeferencing Step By Step

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The purpose of georeferencing is to assign geographic coordinates, i.e. latitude and longitude, to a verbal locality description. Because of uncertainties inherent in many steps of the georeferencing process, a range of coordinates describes a locality better than a single set of coordinates. For the purposes of this project, this range is described as a single point with lat/long coordinates and an error radius around that point calculated using the MaNIS Coordinates and Error Calculator. The resulting circle should include all possible lat/long coordinates for a locality description.Assigning lat/long coordinates to a verbal description is a complicated process that requires subjective interpretation by the georeferencing staff at each institution. MaNIS has compiled a set of guidelines for georeferencers to follow in order to minimize the need for assumptions. Following these guidelines results in highly consistent coordinates with low error rates.


The following is a list of the steps to be followed for georeferencing localities from the HerpNET collaborative gazetteer. By following these steps, we will ensure the consistency in methodology and compatibility of results from all participants.

| Step 1|Step 2| Step 3|Step 4| Step 5| Step 6| Step 7|Step 8|Step 9|Step 10|
|Table 1 All Data fields|Table 2 Data fields not to change |What all finished files should have |
No Georeferencing Reasons|Access97 Database Template |Important Note |

Step 1- Read Georeferencing Guidelines

Read and understand the Georeferencing Guidelines document , print out and read the "Georeferencing for Dummies" document and read the Manual for MaNIS Coordinates and Error Calculator. The MaNIS/HerpNET/ORNIS georeferencing guidelines explain how to georeference and the theory behind it. These must be read first. The "Georeferencing for Dummies" document was developed to ease the process of georeferencing and should be used in addition to the guidelines.

Step 2 - Browse Checklist

Look at the HerpNET Georeferencing Checklist to determine which geographic areas have already been claimed and which are still available for georeferencing.

Step 3- Download Localities

Use the HerpNET Gazetteer to find and download unclaimed localities for georeferencing. Commence your gazetteer query by first looking for North American regions that your institution has strong holdings and resources or simply a desire to georeference. Georeferencing these localities first will ensure that our extended goal of georeferencing all American localities during this project is met, and that any application of HerpNET funds for georeferencing outside the Americas will make the most of the expertise and resources that individual institutions have. Download the localities to your computer as a tab-delimited text file (.txt extension).

Step 4- Import Localities

Open the downloaded locality data in Excel, Access, or any other spreadsheet or database software that can 1) import and export a tab-delimited text file, 2) preserve the column order and structure of the original file, 3) preserve the data types of the imported and exported files without format modifications. Dates should use four-digit years and all digits of original numeric data must be preserved. An explanation of the data fields in the downloaded file is given below in Tables 1 and 2. An Access97 database template that data can be imported into is provided here. The program Access is only available on PC (or virtual PC).
A copy of the template in Excel is available here.

Step 5- Commit

After importing the localities, announce your commitment to georeference a geographic area on the HerpNET email list by sending a message to the HerpNET listserv. In the message, describe the geographic area to which you have committed, e.g., "The MVZ claims Honduras for georeferencing". It is best if you include in the message what values you used for your gazetteer query and how many localities you downloaded, e.g. Country: Honduras, 6790 localities. Your commitment will be posted on the HerpNET Georeferencing Checklist.

Step 6- Georeference

Follow the Georeferencing Guidelines to assign geographic coordinates to the localities in the downloaded data. See below (Tables 1) for an explanation of the fields to be filled in by the georeferencer. Then, use the Georeferencing Calculator to determine the maximum error distance for each locality. Determine the coordinates and error at the same time, since you have to look at a map to find coordinates and to determine extents of named places. Some useful sources of digital maps & gazetteers can be found on the resources page.

IMPORTANT: Do not change existing data and do not georeference or calculate error values for localities that already have coordinates. Also, do NOT georeference any MVZ localities that appear in the gazetteer.

Step 7- Save Finished Localities

Rename the file you have been working on (the Excel spreadsheet, Access database or any other format) to reflect the institution at which the georeferencing has taken place, the geographic scope of its content, and the date the file was finished. For example, a file of Peruvian localities finished by the Field Museum on Halloween would be FMNH-Peru-2003-10-31.txt. Make a backup of this file and store it in a safe place.

Step 8- Sending Finished Localities

Send files directly to atrox@berkeley.edu or atrox10@gmail.com, informing Carol separately at atrox@berkeley.edu that you will be sending the files and which ones you are sending back. The file will be checked for data integrity and saved. If there are problems with the data, Carol will get back to you to resolve them.

Step 9- Repeat

Stand up, stretch your fingers,congratulate yourself and return to Step 2.


Data Fields Included In the Downloaded File:

The data provided in the download file are meant to aid in the georeferencing process. An explanation of each of the fields is given below in Tables 1 and 2. The proliferation of seemingly redundant fields is the result of creating a gazetteer with a superset of all of the locality-related fields currently used by the collaborating institutions. Not every field is used by every institution. Only the fields listed below in (Table 1) will be updated in the collaborative gazetteer when the data are returned. The rest (Table 2) should be considered a part of the original locality description, which will NOT be updated in the gazetteer.

Please make additions or changes only to the following fields:

Table1. Data Fields to be completed by Georeferencing Staff

Field Name

Field Description

DeterminedByPerson

The name of the person who georeferenced this locality.

DeterminedDate

The date on which the locality was georeferenced completely.

DeterminationRef

The reference used to make the Lat-Long determination (e.g., map, software, gazetteer, etc.) The reference should be specific enough for another person to find the locality in the same resource.

OrigCoordSystem

The original coordinate system in which the Lat-Long was recorded. Use ONLY one of the following values: decimal degrees, degrees minutes seconds, or UTM. When entering the determined Latitude and Longitude, it should be in the OrigCoordSystem indicated here. Translations to other coordinate systems will be made in bulk when the data are returned.

Datum

The geodetic datum of the resource used to measure the coordinates, e.g. NAD27, WGS84. If the datum is not recorded on the resource, enter not recorded.

DecLat

The latitude in decimal degrees. Preserve as many digits of precision as given by the source. North is a positive real number between 0 and 90. South is a negative real number between 0 and 90.

DecLong

The longitude in decimal degrees. Preserve as many digits of precision as given by the source. East is a positive real number between 0 and 180. West is a negative real number between 0 and 180.

LatDeg

The degrees part of latitude, if latitude was determined in degrees minutes seconds.

LatMin

The minutes part of latitude, if latitude was determined in degrees minutes seconds.

LatSec

The seconds part of attitude, if latitude was determined in degrees minutes seconds.

LatDir

The latitude direction, if latitude was determined in degrees minutes seconds.

LongDeg

The degrees part of longitude, if longitude was determined in degrees minutes seconds.

LongMin

The minutes part of longitude, if longitude was determined in degrees minutes seconds.

LongSec

The seconds part of longitude, if longitude was determined in degrees minutes seconds.

LongDir

The longitude direction, if longitude was determined in degrees minutes seconds.

UTMZone

The UTM zone, if the coordinates are in UTM.

UTMEW

The easting in a UTM coordinate.

UTMNS

The northing in a UTM coordinate.

MaxErrorDistance

The maximum error distance for the Lat-Long determination as calculated using the MaNIS Coordinates and Error Calculator.

MaxErrorUnits

The units of the error distance. These MUST be the same as for the distance measures in the specific locality description.

LatLongRemarks

Any assumptions and comments about the determination of the coordinates. It is especially important to note anything that is not covered in the georeferencing guidelines.

CaptiveFlag

A flag to denote whether this location represents captive individuals. The default value is zero, which means that the locality represents wild occurrences. Change this field to one if the locality is not a wild one (e.g., "San Diego Zoo", "captive bred at Hastings", etc). Do NOT georeference captive records.

NoGeorefBecause

If a locality cannot be georeferenced, give the reason in this field. List of reasons.

LocalityAnnotation

Use this field to make comments about a locality itself for the edification of the institution that provided it. Institutions will use these annotations to rectify inconsistencies within the locality (e.g., Bakersfield is not at an elevation of 6000 ft) or between the locality and the higher geography (e.g., Bakersfield is in Kern Co., not Inyo Co.). Do not make any changes to the original locality description.

Extent

The distance from the center of the named place to its furthest extent. A measure of the area covered by a named place used as a marker in the locality description. Please make sure you have read and understood the Georeferencing Guidelines section that explains how to estimate the extent of a named place.

Named Place

The town, river, building, intersection, or other feature that was used as a marker to determine the geographic coordinates.

Finished localities should either be georeferenced or have a NoGeorefBecause completed field.
All georeferenced localities MUST have:

1) DecLat and DecLong

2) Datum

3) Extent

4) Named Place

5) MaxErrorDistance and MaxErrorUnits

6) OriginalCoordSystem

ALL localities, georeferenced or not, MUST have:

1) DecLat and DecLong or NoGeorefeBecause

2) DeterminedBy

3) DeterminedDate

4) DeterminationRef


Please do NOT make any changes to the following data fields. These fields contain the original locality description as received from the institution that holds specimens from that locality.

Table2. Fields that should not be changed

Field Name

Field Description

LocalityID

A unique identifier for the locality record. This will be used to link the lat/long back to the institutions' original database and must not be changed under any circumstances.

CollectionCode

The code institution that provided the locality record.

Highergeog

A concatenation of all of the geopolitical subdivision levels above specific locality.

Spec_Locality

The text of the specific locality description.

ElevationText

Elevation information as descriptive text.

MinElev

The minimum elevation in an elevation range, as text.

MaxElev

The maximum elevation in an elevation range, as text

ElevUnits

The units in which the MinElev and MaxElev were recorded.

LatText

The latitude, as text. If this field is populated it means that the locality was downloaded with Lat-Long information already provided and the locality should not be georeferenced.

LongText

The longitude, as text. If this field is populated it means that the locality was downloaded with Lat-Long information already provided and the locality should not be georeferenced.

TRS

Township, Range, Section information as text.

Township

Township, as an integer.

TownshipDir

The Township direction, N or S.

Range

Range, as an integer.

RangeDir

The Range direction E or W.

TRSSection

The section in a TRS description as an integer.

TRSPart

The section part description.

DetByAgentID

The ID of the person who made the determination. If this field is populated it means that the locality was downloaded with Lat-Long information already provided.


NDanos 16JUL2003. Modified from John Wieczorek, Rev. 5 Sep 2002, MaNIS Georeferencing Steps (http://elib.cs.berkeley.edu/manis/GeorefSteps.html)

University of California, Berkeley, CA 94720, Copyright 2001, The Regents of the University of California.

Updated by CL Spencer, 11 Oct 2007.



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