0

I'm taking an online GIS course of a reputed university and the instructor categorized GIS data types as

  1. Raster
  2. Vector, and
  3. Triangulated Irregular Network (TIN).

Now I know that TIN is a vector based surface consisting of non-overlapping triangles. But can it be considered a different data type? Especially when it is vector based by its very definition.

2
  • I wouldn't classify it that way, but this seems more a matter for discussion than an answerable question. You should probably discuss this with your instructor first.
    – Vince
    Oct 7, 2023 at 13:43
  • Well, in my point of view it is an answerable question (see my answer) and it is obvious that TINs are maybe a specific form of GIS vector data, but not a "major data type" like vector or raster data.
    – winnewoerp
    Oct 7, 2023 at 13:49

2 Answers 2

2

An irregular mesh of triangles is clearly a vector data set because triangles are just polygons. The OGC Simple Features definition agrees, and includes TIN in their structure diagram. When people say "vector data", at least in Open GIS contexts, they mean "Simple Features":

enter image description here

But if you read these docs you'll see that this does not define any properties of the triangle or the vertices. Most usage of TINs (or other "meshes") are useful because they are interpreted as each triangle being a planar linear interpolation of values at the three vertexes of the triangle (often heights, to define an elevation model), and in this context they define a complete continuous planar surface with a value defined at all (x,y) coordinates, much like a raster data set (where the raster data is defined as constant within cells, rather than defined only at grid points).

I think this use of TINs to define elevation models is the source of confusion, and I can trace this back to when I started working in GIS in 1990, when ARC/INFO had a specific module for TIN analysis. The use of a TIN for a DEM was probably because storage space was at a premium and a DEM defined by a TIN can efficiently define flat surfaces with few triangles but adapt to rugged areas with more triangles to not lose detail. Computing linear interpolations at any point in the triangle is quite fast. Contrast this to a raster DEM where you have a constant cell size even if half your area is flat.

1
  • That definitely makes sense. Thanks for the help.
    – SVK99
    Dec 10, 2023 at 11:24
0

No, TINs cannot be considered a GIS data type at the same level as vector and raster data. Triangulated irregular networks are basically the same as 2D or 3D GIS vector data. They consist of triangular polygon surfaces derived from a set of vertices (points).

You can find additional information in the TIN in ArcGIS Pro documentation.

Your Answer

By clicking “Post Your Answer”, you agree to our terms of service and acknowledge you have read our privacy policy.

Not the answer you're looking for? Browse other questions tagged or ask your own question.