The Esri TIN format is a popular yet proprietary geospatial vector data format for geographic information system (GIS) software for storing elevation data as a triangulated irregular network.
The Esri TIN format can spatially describe elevation information including breaking edge features.
[1] [2] A TIN stored in this file format can have any shape, cover multiple regions (e.g. islands) and contain holes (e.g.
[4] Since then, the Virtual Terrain Project, an open-source software, has implemented support for reading the format, without the need of ArcGIS being installed.
superpoints) and k triangles, the file sizes calculate to: Contains and array of X and Y coordinate values, one pair for each point of the TIN.
Contains an array of indices and separators, that defines the outer boundary of the TIN and its holes.
Contains an array of bits (stored in 4 byte integers) that specify the visibility of the triangles of the TIN.
Record 2: The data of record number 2 contain the following variable length structure: Bit 0 (least significant bit) of the first integer contains the visibility flag (invisible if set to 1) of the first triangle defined in tnod.adf.
Bit 1 of the first integer contains the visibility flag (invisible if set to 1) of the second triangle, and so on.
Depending on the information stored in the TIN, some extra files are needed.
The file can be either in the Esri flavour of the well-known text representation of coordinate reference systems format (WKT), a simple keyword-value notation (Keyword: Projection, Datum, Spheroid, Units, Zunits, Xshift, Yshift, Zone,...) or have a single line {B286C06B-0879-11D2-AACA-00C04FA33C20}, which signifies an unknown coordinate system.
Each data set is structured as follows: Contains are array of 4 byte integer value, one for each (tagged) point of the TIN.
The file structure remains the same, just the field containing the number of breaking edges is additionally used.
Each data set is 16 byte long and structured as follows: Since ArcGIS 10 this file has changed a little.
Breaking edges are still marked using negative values, but the index don't point to the file position in tnod.dbf and tedg.dbf anymore, instead the absolute of the value is the number of the entry of the breaking edge in teval.dbf.
In the absence of an official file format description this term was chosen to reflect the properties of these points.
The triangles that are built with these points are usually masked (made invisible) in the tmsk.adf file.