Caris NTX Reader/Writer

Licensing options for this format begin with FME Desktop Professional Edition.

The CARIS NTX Reader/Writer allows FME to read and write the CARIS interchange file format known as NTX.


This format is a sequential binary format designed to hold hydrographic or topographic data. Its purpose is to enable data exchange for CARIS users and contractors.

NTX files may contain both two-dimensional (2D) and three-dimensional (3D) features. NTX files store feature geometries as well as a limited number of attributes. The files contain information giving the kind of feature as well as how to view or draw it; that is, both unsymbolized and symbolized forms. They also contain the information necessary to relate the X Y coordinates to latitude and longitude, and different groups of data can have different geographic references.

NTX files do not explicitly store arbitrary attribute values but instead use a feature coding approach in which unique feature codes are assigned to the different types of features stored within the dataset. The FME looks for an extension of .ntx for the input NTX files, but accepts any NTX file as input regardless of the filename or extension.

The NTX file format allows for both big-endian (UNIX) and little-endian (PC) files. The FME will read both types of files, determining the format automatically.

There are ten feature types stored in NTX files, as follows:

  • compacted lines
  • point-to-point lines (also containing dashed lines, circles, and arcs)
  • names
  • ASCII text
  • text with position
  • text blocks
  • symbols (with labels)
  • spot heights
  • soundings
  • header information

FME considers an NTX dataset to be a single CARIS NTX file.

Reader Overview

The NTX reader simply opens the input file, and immediately starts reading features and returning them to the rest of the FME for processing. The reader doesn’t have any requirement for definition statements, as there are no user-defined attributes. Any features flagged with the deleted flag are ignored and not output. All line features flagged with the closed flag are output as polygons.

Each feature that is returned has its feature type set to the geometric type of the feature, as follows:

  • ntx_compacted_line
  • ntx_ptp_line
  • ntx_circle
  • ntx_ascii_tex
  • ntx_name
  • ntx_symbol
  • ntx_text
  • ntx_sounding
  • ntx_spot_height, or
  • ntx_header

Writer Overview

The NTX writer creates and writes feature data to the NTX file specified by the writer dataset. Any NTX file having the same name is overwritten with the new feature data.