TIN editing basics

Available with 3D Analyst license.

You can edit existing triangulated irregular networks (TINs) and add any supplemental data you have. If you have a TIN surface representing the study area and data that shows how the surface has changed since the TIN was constructed, you can add these features to the TIN and optionally save it as a new TIN. For example, this could include line feature classes that represent roadways or new elevation data, such as point feature classes that show mining excavation in the study area.

There are two ways to edit a TIN in: using the interactive TIN Editor in a map view and using the Edit TIN geoprocessing tool in the TIN Management toolset in the 3D Analyst toolbox.

The TIN editing tools allow you to interactively edit individual features that contribute to the TIN surface. The TIN editing tools allow you to directly add, remove, or modify TIN nodes, breaklines, or polygons. For an overview of the TIN Editor, see Interactive TIN Editor in ArcGIS Pro.

The process of editing TIN surfaces with geoprocessing tools can include adding new feature classes to an existing TIN, copying a TIN, or defining the data area. The existing TIN may already have features in it, or may be an empty TIN with no features. Editing TIN surfaces using geoprocessing does not involve changing attributes, or values, of nodes or triangle faces. Those changes must be accomplished through the interactive TIN Editor, editing the source data, or converting features in the TIN to vector features (points, lines, or polygons).

The following summary describes how source measurements are represented on a TIN surface. For more information on how to modify these properties, see Edit data contributing to a TIN with geoprocessing tools.

Height source

The height source in geoprocessing tools is listed as height_field. If the input feature has z-values associated with it, they can be incorporated into the TIN surfaces. An example is line features that represent breaklines that can help further define the TIN surface. Breaklines normally have an elevation associated with each vertex in the line layer. If the feature is 3D enabled, the height source contains either shape or feature z-values represented as a separate attribute.

Surface feature type (SF_type)

The surface feature type in geoprocessing tools is listed as SF_type. A feature class added to a TIN surface can be any one of several types listed in this property. The surface feature type helps define the TIN surface and categorizes the input features according to behaviors associated with their vector types. Points, for instance, can only be added as mass points. Mass points are added as individual nodes in the TIN. Line features can be represented as hard or soft breaklines, and polygons can be hardclip, softclip, hardreplace, softreplace, harderase, softerase, hardvaluefill, or softvaluefill.

Hard and soft qualifiers for line and polygon feature types are used to indicate whether a distinct break in slope occurs on the surface at their location. A hard line is a distinct break in slope, while a soft line is represented on the surface as a more gradual change in slope.

Breaklines are enforced in the triangulation as a series of triangle edges. Steiner, or densification, points are added as needed to maintain conformance to a Delaunay triangulation.

Clip polygons delineate the data area, or interpolation zone, of the TIN. Their boundaries are enforced in the triangulation as breaklines. Triangles falling outside the polygons are masked. They become NoData as far as interpolation is concerned. Erase polygons also influence the data area of the TIN. Their boundaries are enforced in the triangulation as breaklines. Then triangles falling inside the polygons are masked. Replace polygons are used to define flat areas. Their boundaries are enforced in the triangulation as breaklines using a constant height. All nodes inside the polygons have their z-values set to the same constant.


The tag value in geoprocessing tools is listed as tag_field. Tag value fill polygons assign integer values, that are used as a form of attribution to triangles. Their boundaries are enforced in the triangulation as breaklines. Triangles inside these polygons are attributed with the tag values. Tags are stored as signed long integers. Triangle tags represent user-defined criteria about areas. Landcover codes are an example. The TIN can subsequently be rendered by symbolizing the triangles based on these tags. The Explore tool also reports their values.

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