MassGIS logo

MassGIS maintains a comprehensive, statewide database of spatial information for mapping and analysis supporting emergency response, environmental planning and management, transportation planning, economic development, and transparency in state government operations.

Visit the MassGIS website

Browse all MassGIS data layers

Other Access

The information on this page (the dataset metadata) is also available in these formats.

JSON RDF

via the DKAN API

MassGIS Data: Digital Orthophoto Topographic Breaklines

April 2003

Breaklines define and control surface behavior in terms of smoothness and continuity. As their name implies, breaklines are linear features.

Download this layer
Zipped shapefile (205 MB)

 They have a significant effect in terms of describing surface behavior when incorporated in a surface model such as a triangulated irregular network (TIN). Breaklines can describe and enforce a change in the behavior of the surface. Two types of breaklines are included in this layer: hard and soft. Hard breaklines define interruptions in surface smoothness and are typically used to define streams, ridges, shorelines, building footprints, dams, and other locations of abrupt surface change. Soft breaklines are used to ensure that known "Z" (elevation) values along a linear feature (such as a roadway) are maintained in a TIN. Soft breaklines can also be used to ensure that linear features and polygon edges are maintained in the TIN surface model by enforcing the breakline as TIN edges. Soft breaklines, however, do not define interruptions in surface smoothness.  

The breaklines in this layer were created using Digital Terrain Model (DTM) data points collected during the production of the 1:5000 Black and White Digital Orthophoto images . They were used as input  in creating TINs which were the basis for the 3-meter Elevation Contours (1:5,000) datalayer. These breaklines are accurate to National Map Accuracy Standards (+- 1.5 meters).

In ArcSDE the layer name is BREAKLINES_ARC.

Production

The breaklines were produced using the Arc/INFO GENERATE command. The INPUT file was a .GEN file produced with an awk script which contained DTM point coordinates coded either "hard" or "soft". All of these data were extracted from the original DTM files collected on stereo analytic plotters. The Orthophoto Index Grid coverage was used as a CLIP coverage as the DTM points overlap 5-10 percent in both directions.

Attributes

In the layer's arc attribute table, hard breaklines have an L-ID of 3. The L-ID of each soft breakline is coded 2.

Maintenance

This datalayer is maintained by MassGIS. For related datalayers see:

Last Updated 10/5/2017

Items

Contributor
Modified Date
2017-12-26
Release Date
2017-12-26
Identifier
363937f4-c096-4336-b1f3-6d1336ab47bb
Spatial / Geographical Coverage Location
Massachusetts
License
Author
MassGIS
Contact Name
MassGIS
Contact Email
Public Access Level
Public
Data Quality
False
Content Type
Language
English (United States)