Summary

Description

Terrain data, as defined in FEMA Guidelines and Specifications, Appendix N: Data Capture Standards, describes the digital topographic data that were used to create the elevation data representing the terrain environment of a watershed and/or floodplain. Terrain data requirements allow for flexibility in the types of information provided as sources used to produce final terrain deliverables. Once this type of data is provided, FEMA will be able to account for the origins of the flood study elevation data. (Source: FEMA Guidelines and Specifications, Appendix N, Section N.1.2).LIDAR data is remotely sensed high-resolution elevation data collected by an airborne collection platform. By positioning laser range finding with the use of 1 second GPS with 100hz inertial measurement unit corrections; Terrapoint's LIDAR instruments are able to make highly detailed geospatial elevation products of the ground, man-made structures and vegetation. The LiDAR flightlines for this project was planned for a 50% acquisition overlap. The nominal resolution of this project without overlap is 1.25m (Optech) and 1m (ALTMS) spacing. Four returns were recorded for each pulse in addition to an intensity value. GPS Week Time, Echo, Intensity, Flightline number and scan angle attributes were provided for each LiDAR point. Data is provided as random points, in LAS v1.0 format, classified according to ASPRS Class Code 2=Ground 1=Undefined.