Types of data supported in LAS datasets

There are two major data sources to LAS datasets: lidar data stored in LAS files and surface constraints stored in shapefiles or feature classes.

Lidar

Lidar (light detection and ranging) is an optical remote-sensing technique that uses laser light to densely sample the surface of the earth producing highly accurate x,y,z measurements.

General characteristics of lidar include:

A LAS dataset is designed and optimized to support LAS files from an airborne lidar collection. The LAS dataset can support lidar data in LAS format from a terrestrial collection, however, they should only be displayed as points. With an airborne collection you can visualize the LAS dataset in ArcMap, ArcScene, and ArcCatalog as points or as a triangulated surface.

Surface constraints

Surface constraints are surface features stored in either geodatabase feature classes or shapefiles, which are usually derived from some sort of remote sensing technique like photogrammetry.

Photogrammetrically derived breaklines:

GPS Points:

Surface constraint type

Feature class

Z-value source in the feature class

Thematic data type examples

Points (x,y,z locations)

Point feature class

  • Shape geometry; x,y,z per vertex

or

  • Attribute column holding one z-value per shape
  • Spot heights
  • Survey points
  • GPS points

Polygon feature class

  • Shape geometry; x,y,z per vertex

or

  • Attribute column holding one z-value per shape
  • Shoreline delineation

Breaklines (hard or soft)

Line feature class

  • Shape geometry; x,y,z per vertex
  • Attribute column holding one z-value per shape
  • No height source; z-values interpolated for each feature from the surface before being added
  • Contours
  • Edge of pavement
  • Water lines (streams, rivers, canals, and shorelines)

Polygon feature class

  • Shape geometry; x,y,z per vertex
  • Attribute column holding one z-value per shape (such as a shoreline)
  • No height source; z-values interpolated for each feature from the surface before being added
  • Lake shoreline

Clipping polygons (hard or soft)

Polygon feature class

  • Shape geometry; x,y,z per vertex
  • Attribute column holding one z-value per shape (such as a shoreline)
  • No height source; z-values interpolated for each feature from the surface before being added
  • Study area boundary

Erase polygons (hard or soft)

Polygon feature class

  • Shape geometry; x,y,z per vertex
  • Attribute column holding one z-value per shape
  • No height source; z-values interpolated for each feature from the surface before being added
  • Lake shoreline
  • Obscured areas (dense forest canopy)

Replace polygons (hard or soft)

Polygon feature class

  • Shape geometry; x,y,z per vertex
  • Attribute column holding one z-value for all vertices in each shape
  • Water bodies

Related Topics

3/5/2014