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NAD 27 or WGS84 ???

Although some time ago the Geographic Institutes in Latin America officialized the change to wGS84 as a standardized projection, the change in use level goes a bit slow. Actually the projection is always cylindrical and the change hardly implies a Datum change between NAD27 and NAD83, however the implications become more complex than moving the maps a uniform vector. Among the most important reasons that affect standardization are the following:

1. The majority of existing cartography in many Hispanic countries is in NAD27, And little product has been generated in the new projection. Therefore the easiest thing is to not complicate life and use information in the formats that abound.

2. For “cartographic” purposes, It is often unaffected to use both systems, aspect that is harmful because in some cases the information becomes “Painted maps“. However, those of us who work from the municipal approach, such as cadastre, the projection aspect is vital, if you want to manage nomenclatures of cadastral key under the criterion of quadrants; since the grids in both systems are different, which implies that the identity of a property changes if we migrate from one system to another. Additionally most new GPS do not bring all the options of the NAD27 projection.
2. The autonomy that the governmental instances it is affected by the lack of leadership on the part of the regulatory entities in matters of cartography and territorial ordering. Although the official changes to the new projection are known many years ago, in some cases a little more is required than to say it, since there must be inter-agency spatial data commissions that can regulate the uniformity of projection for national management. The loss of leadership in the last century, after the US army has let down its guard, has caused major setbacks in some countries where they have only been left with printed materials or in similar formats, without haste to migrate to technologies for the publication of information according to time.

3. The fact that many computer systems have no problem in Reproject data on the fly It makes standardization not urgent. However it is not enough to reproject, sometimes it is necessary to normalize information, because in many cases what is done is to move the cartography a uniform vector of so many meters to the north and so many to the east, however the reprojection implies much more than that in function of the scale and relevance of the data.

It is possible to complicate or simplify things with Google Earth, Jeje Which reads as follows:

  • Normally, the data you import to Google Earth are created with a specific geographic coordinate system, such as the Universal Transverse Mercator (UTM) projection and a Datum NAD27 (Datum Of North America of 1927)
  • Currently, Google Earth does not support files that use the NAD83 projection.

Golgi Alvarez

Writer, researcher, specialist in Land Management Models. He has participated in the conceptualization and implementation of models such as: National Property Administration System SINAP in Honduras, Management Model of Joint Municipalities in Honduras, Integrated Cadastre-Registry Management Model in Nicaragua, Territory Administration System SAT in Colombia . Editor of the Geofumadas knowledge blog since 2007 and creator of the AulaGEO Academy that includes more than 100 courses on GIS - CAD - BIM - Digital Twins topics.

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  1. Saludes: my criterion based on surveys.
    In zone 16 P, a UTM WGS 84 coordinate, taken in that zone, you can find the equivalent in NAD 27, approximately 200 meters, in a North-South geographical direction.

  2. first they have to know that the GPS is a planimetric measure and is not real to the real surface or that is where there is a lot of relief its presicion is quite erroneous in terms of its measurements

  3. I consulted the converter (
    , And I wonder how do the conversion from nad27 to wgs84? So that I can use the same algorithm to program it in java, python, etc.
    I have a database with records that contain coordinates in NAD27, and I want to update them to WGS84.
    So, the program that I have to code must read and transform register by register (it is an option). But I would also like to be able to transform “on the fly”, interactively.
    As you can see, I need the transformation algorithm.

  4. Much Bla Bla and no one knows how to convert wgs84 to nad27 or biceversa ???? Just say how they become and do not send us to another place to continue spending time.


  6. With the same know the tool to use with arc map to convert wgs 84 to nad 27

  7. Can someone tell me which tool to use in 10 arc map to change coordinates nad 27 to wgs 84 or biseversa

  8. It's not the same, but it's almost the same. The differences are less than a millimeter, but take a look at the regulations of INEGI, which reads on page 8:

    Any horizontal geodesic survey must comply with the provisions of the Technical Standards for Geodetic Surveys, where it is specified that the reference system that Should be used in said
    Type of surveys is the International Terrestrial Reference Framework (ITRF)
    Of the International Rotation Service (IERS) for year 1992 with data from the 1988.0 period, established as the official reference system for Mexico.

    However for surveys of geographic information for cartographic purposes The WGS84 system can be considered equivalent (World Geodetic System) which is to which the Global Positioning System (GPS) is referenced.

    I leave the links:

  9. I would like to know if anyone can tell me if the wgs84 datum and itrf92 is the same, Thanks.

  10. Greetings colleagues….!

    I started in this environment by purchasing a Garmin 60SCx GPS and observed the following:

    1. For navigation and hiking is perfect even following your internal map.
    2. For distance measurements also has good accuracy.
    3.To measure elevations and / or heights has good acceptance in its accuracy and improvement if calibrated with a landmark or cartographic landmark.
    4. and….here is my concern in the measurements of specific locations, UTM coordinates have variations of up to 400 or more meters in both the X and Y coordinates and they worsen or improve depending on the “datum” data formats and tables that I choose from your memory, for example: NAD27, GRS80, SOUTAMER69, EUROPE79 etc…

    The best was Europ79, which lowered the errors to 100 mts and 200mts respectively, in the end none has been +/- accurate.

    Could someone guide me, why so much punctual variation ...?

    Thank you….

  11. Hello everyone. I would like to publish practical autocad manuals. everything that is being published until today, is perfect, but, it would not be comprehensible if we do not know the basic autocad, then it would be necessary to first teach us the basic autocad for the complementation of these courses.

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