Coordinate formats allow you to define exactly how the coordinates in a file should be represented. When
you perform a batch conversion, you first define how the input coordinates are define. This is necessary since
CoordTrans needs to be able to understand the coordinates in the file. Once understood, CoordTrans can write
the coordinates to a destination file using another coordinate format. Thus, you can choose to represent
your coordinates in any way you like!
CoordTrans maintains a database of coordinate formats that you can edit as you wish. By selecting
Tools->Coordinate Formats in the batch converter dialog, you reach a coordinate format manager. Here
you can create, edit, remove, import and export coordinate formats.
|Figure 1 - managing the coordinate formats
There are two ways to create a new format - you can create a coordinate format from scratch or you can
base your new coordinate format on an existing format. To create a coordinate format from scratch, you
simple click new and fill out the fields. To base your format on an existing format, you need to clone
the existing formats. To do this, simply select the existing format, right click it an select clone. Now you
have an identical copy of the coordinate format which you can alter without editing the existing format!
A Coordinate Format can be defined in two ways; either using a simple coordinate format expression or a regular expression. The simple
expression will generate a regular expression, so it is possible to start with a simple expression and refine it by altering the
The fastest way to define a coordinate format is to use a simple expression, which is composed of the letters D, M and S. Uppercase characters
represent the integer part and lowercase characters represent the decimal part. Thus, D represents the integer part of degrees (i.e. 90 if
degrees is 90.56) and d represents the decimal part (i.e. 56 if degrees is 90.56).
Coordinate formats can be used both to interpret a coordinate read from a text file, and to format a coordinate so it can be written
to the text file. However, different rules apply to input and output coordinate formats. The distinctions are:
The first X letters of a specific in an input coordinate format means "X or more occurances", while it means "at least X occurances"
in out put formats. This means that DD means that the integer part of degrees occupies two or more characters in the input, while it it
should occupy at least to characters in the output. If the degrees does't require two characters, i.e. if it is less than ten, it
will be padded with zeros.
Input formats can have optional part. For instance, a decimal degrees coordinate format would be D.d, i.e. a coordinate such as
12.123 would be a valid coordinate. However, 12 is also a valid coordinate. Thus, you can make the decimal part optional by surrounding it
with "(" and ")". The input format would then be D(.d). However, this is not valid for output. Instead the output format must be D.d. If the
actual coordinate doesn't allow a decimal, the decimal part will be 0.
If you define an input coordinate format as D.ddd, it will mean that input coordinates contains three or more decimal numbers. However, the
output coordinate format D.ddd means that the output contains no less than one and no more than three decimals.
An input coordinate format can divide numbers into sections, which is useful for an input such as 1,000,000.00 for grids. Such a coordinate
format would be written D(,DDD)(,DDD)(.d). That can however not be used for output.
|18° 48' 40.764"
The coordinate in this example is a very common coordinate format generally referred to as a DMS-format. It means that the coordinate is
defined through a combination of degrees, minutes and seconds. This can easily be understood by CoordTrans by defining an appropriate
coordinate format. We note above that we have 18 degrees, 48 seconds and 40.764 seconds. Degrees are represented by D, minutes M, seconds
S and s respectivelly. So the coordinate format can be defined as
D° MM' SS.s"
This means "one or more characters for degrees", "two characters for minutes", "two characters for seconds" and "one or more characters in
decimal seconds". However, 18° 48' 40" is also a valid coordinate, so we need to make the decimal part of seconds. This done by
encapsulating the decimal part with "(" and ")". The format then becomes:
D° MM' SS(.s)"