Victorian Bounding Box
for MapInfo Professional users

Who is affected by the bounding box?
What you must do
Background
The Victorian Bounding Box
Defining projections in MapInfo Professional
Converting existing MapInfo Professional tab files
MIF file and CoordSys line
Further information

Who is affected by the bounding box?
Any MapInfo Professional user that wants to store MapInfo Professional data to millimetre precision and cover Victoria should use the projections defined in this document.

The information in this document has been prepared in consultation with MapInfo Australia. The Victorian Spatial Council supports this initiative.

What you must do
If you are using a version of MapInfo preceding V9.0, and the software does not have the defined projections, download the mapinfow_victoria.prj (PRJ - 1 Kb)
file and add it to your MAPINFOW.PRJ file as described in this document.

Store, manipulate and supply Mapinfo Professional data using the projections defined in this document.

Read the brochure Victorian bounding box 2006 (PDF - 674 Kb)
if detailed background and technical information about the Victorian bounding box is required.

Background
The Department of Sustainability and Environment and the Department of Primary Industries (DSE/DPI) store their corporate spatial data to millimetre precision. When converting this data to a MapInfo Professional file using MapInfo Professional’s Universal Translator, a global bounds box is applied resulting in rounding and a loss of spatial precision. Map Grid of Australia (MGA) data covering Victoria can only be stored to 0.01 metre accuracy when the default bounds are applied. Even worse, data stored in geographic coordinates and Vicgrid coordinates can only be stored to 0.1 metre precision when the default bounds are applied.

A centimetre shift may sound trivial when the spatial accuracy of the data is known to be metre rather than sub-metres. This is not so. When translating data, any positional shift is highly undesirable and should be avoided at all times. The shift may be cumulative when the dataset is repeatedly projected from one coordinate reference system to another. Some applications require an exact spatial match and return unexpected results if this is not the case. Processing overheads may be significant when rounding occurs and algorithms need to be applied to overcome a spatial mismatch. Application of a fuzzy tolerance may complicate data usage. Finally, many issues may be encountered when the data is edited and stored back in the source database.

To overcome these problems, various government departments and organisations within Victoria have adopted their own bounds to store data to millimetre accuracy. This is often unsatisfactory as many of the issues discussed in the previous section are encountered unless the bounds are identical.

The Victorian Bounding Box
In maximising the spatial coverage of a dataset, the precision in which the data is stored is compromised. That is, the greater the coverage, the lesser the precision of the stored data. Therefore, to create a dataset that enables storage of data to millimetre accuracy, the bounds must be limited. The bounding box specified has been carefully selected to cover an area of most interest to Victoria while storing the data to millimetre precision.

The bounds endorsed for commonly used coordinate reference systems in Victoria are shown on the map within the attachment Victorian bounding box 2006 (PDF - 674 Kb)


Geographical Bounds are:
X 138 to 154 (degrees)
Y - 44 to –28 (degrees)

Map Grid of Australia (MGA) Bounds are:
X - 500,000 to 1,500,000 (metres)
Y 5,000,000 to 7,000,000 (metres)

Vicgrid94 Bounds are:
X 1,500,000 to 3,500,000 (metres)
Y 1,500,000 to 3,500,000 (metres)


For further background and technical information about the Victorian bounding box, down load the brochure Victorian bounding box 2006 (PDF - 674 Kb)


Defining projections in MapInfo Professional
The following MapInfo Professional MAPINFOW.PRJ projection records have been defined to enable storing of data at millimetre precision and provide spatial coverage of Victoria and its surrounding environs:

“VIC VicGrid66 (AGD 66) ", 2003, 12, 7, 145, -37, -36, -38, 2500000, 4500000, 1500000, 3500000, 3500000, 5500000
“VIC VicGrid94 (GDA 94)", 2003, 116, 7, 145, -37, -36, -38, 2500000, 2500000, 1500000, 1500000, 3500000, 3500000
"VIC AMG Zone 54 (AGD 66)", 2008, 12, 7, 141, 0, 0.9996, 500000, 10000000, -500000, 5000000, 1500000, 7000000
"VIC AMG Zone 55 (AGD 66)", 2008, 12, 7, 147, 0, 0.9996, 500000, 10000000, -500000, 5000000, 1500000, 7000000
"VIC MGA Zone 54 (GDA 94)", 2008, 116, 7, 141, 0, 0.9996, 500000, 10000000, -500000, 5000000, 1500000, 7000000
"VIC MGA Zone 55 (GDA 94)", 2008, 116, 7, 147, 0, 0.9996, 500000, 10000000, -500000, 5000000, 1500000, 7000000
"VIC Longitude / Latitude (AGD 66)", 2001, 12, 138, -44, 154.666666667, -27.333333333
"VIC Longitude / Latitude (GDA 94)", 2001, 116, 138, -44, 154.666666667, -27.333333333

MapInfo Professional will support these map projections in releases after version 8.5. If these records are not present in the MAPINFOW.PRJ projection file, they must be added by downloading the MAPINFOW_VICTORIA.PRJ file and appending it to the Mapinfo Professional MAPINFOW.PRJ file that is usually found in the directory C:\Program Files\MapInfo Mapx\Program.

If you have successfully installed the Victorian projection file, you will see a new category “Victorian Projections“ at the bottom of the projection category list with the category members listed above.

Converting existing MapInfo Professional tab files
To convert existing MapInfo tab files to files using the Victorian bounding box, open the tab file and save it with the relevant Victorian projection.

For instance, to convert a Vicgrid (GDA94) tab file to use the Victorian bounding box follow the steps below:

Open the tab file
Select File->Save Copy As
In the Save Copy of Table pane, hit the Projection button
In the Choose Projection Window, select the Category Victorian Projections at the bottom of the drop down list.
Select Category Member VicGrid94 (GDA94)
Save the tab file with a different name