2008 FEMA Bare-Earth Lidar: West Creek, Schoharie County (NY)

Terrain data, as defined in FEMA Guidelines and Specifications, Appendix N: Data Capture Standards, describes the digital topographic data that was 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).

Reflective surface data represents the DEM created by laser energy reflected from the first

surface encountered by the laser pulse. Some energy may continue beyond this initial surface to be reflected by a subsequent surface as represented by the Last Return data. Intensity information is captured from the Reflective Surface pulse and indicates the relative energy returned to the sensor as compared to the energy transmitted. The Intensity image is not calibrated or normalized but indicates differences in energy absorption due to the interaction of the surface materials with laser energy at the wavelength transmitted by the sensor.

LIDAR data is used for 3D visualization, elevation based analysis and for feature extraction.

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A final footprint for the 2008 Schoharie Bare Earth project area vist here:

https://noaa-nos-coastal-lidar-pds.s3.amazonaws.com/laz/geoid18/5043/supplemental/ny2008_fema_be_schoharie_m5043.kmz

LAS 1.2 format (class 2 only)

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Any conclusions drawn from the analysis of this information are not the responsibility of the

Federal Emergency Management Agency (FEMA), Sanborn Map Company, Inc, Medina Consultants, the Office for Coastal Management or its partners.

This data can be obtained on-line at the following URL: https://coast.noaa.gov/dataviewer

The data set is dynamically generated based on user-specified parameters.

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Users should be aware that temporal changes may have occurred since this data set was collected

and some parts of this data may no longer represent actual surface conditions. Users should not use this data for critical applications without a full awareness of its limitations.

Microsoft Windows XP Version 5.1 (Build 2600) Service Pack 2; ESRI ArcCatalog 9.2.4.1420

Contracted to meet 1 meter (RMSE) horizontal accuracy.

LiDAR data accuracy determination shall employ the National Standard for Spatial Data Accuracy (NSSDA). Contracted to meet 18.5cm (RMSE) on open bare terrain and 37.0cm for obscured areas.

LIDAR raster data is visually inspected for completeness to ensure that any gaps between flight lines

or loss of signal represents less than 5% of required collection area. LIDAR is self-illuminating and has minimal cloud penetration capability. Water vapor in steam plumes or particulates in smoke may cause reflection of LIDAR signals and loss of elevation information beneath these plumes. Glass structures and roofs may appear transparent to the LIDAR signal and therefore may not register on the reflective surface. Some asphalt formulations have been shown to absorb topographic LIDAR wavelength energy resulting in "pitting" of roof surfaces using this material.

All LAS formatted LIDAR data are validated using commercial GIS software to ensure proper formatting and loading before delivery. This validation procedure ensures that data on delivery media is in correct physical format and is readable.