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[Index]

Sections
Install

Batch Conversion
Grid to Grid
Datum to Grid
Datum to Datum
Manage Grids
Manage Datums
Coordinate Formats
License Key
Supported countries

Manage Datums

One of the new features in CoordTrans v2.0 is that you can manage a large database of grids and datums. This section shows how you can import, export, remove and create new datums that you can use in your conversions.

The Datum Manager

You can find the datum manager by clicking "Datums" under the Tools-menu in the main display (see figure 1). This will show you a dialog similiar to the dialog where you select a datum for conversion, with the addition of some input fields. When you select a datum, the fields will be populated and you can edit the datum as you wish.

Figure 1 - finding the datum manager

Datum Variants

Each datum available for selection is actually a class of datums, i.e. each selectable datum branches out into several datums. The common denominator is the ellipsoid - it is the transformation to WGS84 that differs between the variants of the datums. Each variant encapsulates a parameter set for conversion to WGS84, and a transformation is required for a conversion to take place. The variant that is used when converting is the one set to default in a particular region. You can change this by clicking the Default in [region] button in the variant field of the datum manager. See figure 2.

Figure 2 - selecting a datum variant

Enabling transformations

Some datums in the database, such as RT38 (Stockholm), does not have any transformation to WGS84 associated with them. For this reason, you cannot transform coordinates given in RT38 (Stockholm) - or any of the grids based on RT38 (Stockholm) - to another datum. To enable transformations, you need to add or modify a datum variant and mark it enabled for transformations. To do that, check "Datum transformations enabled" (see figure 3) and fill out the parameters. Once you have done this, you can use the datum as any other datum.

Figure 3 - enabling transformations on a datum

Importing/Exporting

Every datum available in the database and the datums you create can be exported so that it can be imported later or on another machine. To export a datum, simply select it and click export. If you select an existing file you are given the option to merge the datum into the file, which means that you can create a database containing several datums and/or grids and/or coordinate formats. See figure 4.

To import a datum you simply click import and select the file that contains the datums. The datums will be imported and sorted according to the regions they are associated with in the file being imported. If a datum being imported already exists in the database you are given the option to overwrite the existing datum if it differs from the one being imported.

Figure 4 - exporting a datum

Copying a datum to a different region

If you wish your datum(s) to be accessible in another region, just drag the datum(s) from the datum list and drop it/them on the region in which it should be accessible. This will associate the datum(s) with a new region, i.e. if you change the datum(s) in one region, it/they will change in the other as well.

Can't find your datum?

If you don't know where your datum is, you can always search for it in the find-box (see figure 5). To search for a datum, simple enter part of its name, ESRI number, reference meridian etc to search through the database. Note that when you search for a datum, you don't associate the selection with a region. This means that if you remove a datum you have found from a search, it will be completely removed from the database.

Figure 5 - searching the database for a datum

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