Hydrographic Transfer Format
The Hydrographic Transfer Format (HTF) file is an ASCII file that can be opened in any text editor (such as Notepad). It consists of three sections:
• HTF Header, which contains information about the data, such as coordinate system, survey title, date, data density, number of positioning systems etc.
• Sounding Header, which describes the fields that are in the sounding data section.
• The sounding data record contains the exported data on depths and other relevant information.
The total number of fields generated in the sounding data record depends on the survey. At the start of the sounding data record is a Field Population Key that gives each field a 1 bit to show that a field is included, or a 0 bit to show if a field is not included.
For example: [0000111110000000000]
In the above Field Population Key, fields 5 to 9 contain data (hence the 1 bits), while fields 1 to 4 and 10 to 20 contain no data (hence the 0 bits). Fields without data are not written to the HTF file when it is generated. There are a total of 20 HTF fields in the sounding data record. Two additional fields are added by the Export Wizard for beam and profile number. Extra fields can be added, if needed. The HTF export automatically exports
TPU depth and TPU position values if these are included in the track line.
The HTF file contains an ordered list of all possible fields and a description of each field.
Hydrographic Transfer Format Template
Sometimes the same header information can be used for multiple HTF files. The export wizard gives you the option of saving a header for use in another file. Headers are saved as HTFT files (Hydrographic Transfer Format Template). The file is in XML format that can be viewed in a text editor or an XML-compliant Internet browser.