MN GIS/LIS NEWS
Fall 2007
ISSUE 50

MN GIS/LIS NEWS
The Newsletter of the Minnesota GIS/LIS Consortium

Table of Contents

MN GIS/LIS Consortium

2007 Conference
Silent Auction
From the Chair
Polaris Awards
Student Scholarship Competition
Our 50th Issue

State
LMIC Budget Restored
Parcel Inventory Updated
Monument Coordinates in Feet

Governor's Council
New Members
Annual Report
GIS for LCCMR
Regional Collaboration Panel

Regional
Met Council Map Site
MetroGIS Address Dataset

Local
New Funding for Land Data
GeoMoose Web Mapping
Hennepin Co. Mobile Assessor Tool
Remote Aircraft Photography
Clay Co. Addresses

Federal
USGS Maps in GeoPDF
Free Landsat Images
TerraLook Free Imagery
NOAA Satellites
USGS Resources for Teachers

Higher Education
St. Mary's Update

K-12 Education
Geography, History Online

Private
ESRI Map Help

Non-Profits
Google Earth Pro Grants

Other Places
Bring Back Geography!
New Parcel Study
MAPPS Loses Lawsuit

 

Geodetic Control Monument Coordinates Now Published in Feet

By Richard Morey, Minnesota Department of Transportation

 

At the request of several Minnesota surveying and GIS organizations, the National Geodetic Survey (NGS) will now publish state plane coordinates for Minnesota’s geodetic control monuments in feet as well as in meters; the conversion will be based on the U.S. Survey Foot. These monuments are used by the surveying and GIS communities, and most users would like the coordinates published in English (feet) units.

 

For the current datum, NAD83, NGS publishes the coordinates only in metric units until a state informs them which conversion factor the state would like them to use to convert meters to feet. There are two different conversions:

 

  • The international (SI) based upon 1 inch = 2.54 centimeter
  • The U.S. Survey Foot based upon 1 meter = 39.37 inches.

 

While the difference between the two factors is not large, it makes a difference over large distances such as those represented by the state plane coordinate system.

 

States can specify the conversion factor either through legislation or through a letter from the main surveying and GIS organizations within the state agreeing upon which conversion factor to use. Minnesota had not enacted such legislation, although the preferred conversion factor may be inferred by the fact that M.S. 505.20 specifies that NAD27 coordinates are expressed in “U.S. Survey Feet” and NAD83 coordinates are expressed in “meters.”

 

In the absence of legislation, the following groups requested that NGS provide Minnesota’s geodetic control monument locations in English coordinates using the U.S. Survey Foot as the conversion factor:

 

·         Minnesota Department of Transportation

·         Minnesota Society of Professional Surveyors

·         Minnesota Association of County Surveyors

·         Minnesota GIS/LIS Consortium

·         Minnesota Governor’s Council on Geographic Information

 

The letter is posted at: http://www.gis.state.mn.us/Policies/NGS_coordinates.pdf

 

For more information, contact Richard Morey at:  richard.morey@state.mn.us or 651-366-3504.