MTM Notes

This page was generated with GPS Visualizer, using these tracks as input, and the following options: width=1100, fullscreen (?), trackOpacity=100, trackWidth=1, waypointStyle=smallTriangles, permanentLabels.

There are two discontinuities in zones, which can be grouped as follows:

• zones 1 and 2 : reference meridian on degree (53, 56)
• zones 3 to 11 : reference meridian on half degree (58.5 to 82.5 incl)
• zones 12 to 32 : reference meridian on degree (81 to 141 incl)

To cover problem cases, where the MTM definitions here don't match your needs, the reference meridian can be explicitly provided when converting to/from MTM. Right now, the false easting cannot be changed, but if there is need, I could add this too. I don't think MTM makes sense on water.

Some specific notes:

• Nova Scotia

  Nova Scotia really covers four zones, from 3 to 6, but uses only zones 4 and 5, and extends each a bit into the other zones (at the NE and SW tips of the province) to keep things simpler (my understanding).

• Quebec

  Quebec extends zone 3 to its full width, ie. from 57 to 60, and defines a zone 2 (on half degree, ie from 54 to 57 -- so not the same definition as NRCan's zone 2), but there is only a very small part of the province in that zone, and only when using the more extensive border (there is a border dispute here around Labrador).

  With the official NRCan definitions, a very narrow band of Quebec land west of 79.5 appears in zone 12 instead of zone 10 as it should (from Quebec's point of view). This is one place where the "MTM ref meridian" of the tool would be useful (or you can use the QC versions of the tool). I think the border between Quebec and Ontario is just a bit west of 79.5, but GSRUG checks for lon=79.5 exactly (here as well) to switch between zones 10 and 12.

  Note also that SCOPQ (Système de coordonnées planes du Québec) is (perhaps more correctly: uses) MTM. Quebec spans zones 3 to 10 in practice.

• Ontario

  Ontario is a bit confusing at first. Essentially, two sets of zones (ref meridian on half degree, ref meridian on degree) overlap here, separated by a staircase line separating south-eastern Ontario from north-western. See above image.

• Alberta

  Here are the notes I currently have from them.

  Alberta also has three-degree zones that extend to four degrees in some cases, while others are limited to 2 degrees. Here MTM is know as 3TM (3 degree traverse Mercator), and they do not use a false easting.

  • MTM in Alberta is formally known as the 3TM (3-Degree Transverse Mercator) mapping plane. I believe the MTM (or Modified Transverse Mercator) designation is an Ontario-based nomenclature that we didn't adopt out here. As I say, we don't call it MTM in AB.
  • In Alberta we don't refer to the various zones as "zones". Instead we simply break it down by the particular reference (central) meridian to which a user is referring.=20
  • We (Government of Alberta) complicate the matter of 3TM by increasing or reducing the width of the zone in order to accommodate the display of information on our Alberta Survey Control Marker (ASCM) index maps. By this I mean:
    • For ASCMs in urban cadastral areas, the 3TM zone widths are 3-degrees wide where the zone central meridians are 111, 114, 117, and 120 degrees longitude.
    • For ASCMs in rural cadastral areas, the 3TM zone widths are 2-degrees wide for those zones centered around the 111 and 117 degree longitude central meridians; and 4-degrees wide for those zones centered around the 114 and 120 degree longitude central meridians. The reason for this departure from the traditional 1.5 degrees either side of the central meridian is that it allowed us to depict rural ASCMs on 1:250K index maps without having to span onto another mapsheet, but still having the same central meridian.

Other provices do not appear to use MTM zones.

Another view of MTM zones from www.posc.org.

Comments/corrections most welcome: (français, English, Deutsch).