2013 Harford County, MD Aerial Lidar Data

This metadata record describes the classified bare earth lidar data products derived from the Harford County, MD LiDAR project covering the defined project area of Harford County and immediate surroundings.

To acquire detailed surface elevation data for use in conservation planning, design, research, floodplain mapping, dam safety assessments, and hydrologic modeling. LAS and bare earth DEM data products are suitable for 2 foot contour generation and orthorectification of aerial imagery collected in conjunction with the lidar data.

Original deliverable data products generated from the raw aerial lidar data are: LAS format data for: Classified lidar, Bare Earth lidar, First Return (SEM) lidar, classified by flight line lidar, unclassified by flightline lidar. Project Projection, Datums and Units. Projection : State Plane Coordinate System (SPCS) Maryland. Horizontal datum : North American Datum of 1983 (2011)). Vertical datum : North American Vertical Datum of 1988 (NAVD88(GEOID03)) Units : U.S. Survey foot. Projection, units, and vertical datum have been changed for ingest into the Digital Coast Data Access Viewer.

Harford County, MD provides the geographic data "as is". This organization makes no guarantee or warranty concerning the accuracy of information contained in the geographic data. Also, this organization makes no warranty, either expressed or implied, regarding the condition of the product or its fitness for any particular purpose. The burden for determining fitness for use lies entirely with the user. Although these files have been processed successfully on computers at this organization, no warranty is made by this organization regarding the use of these data on any other system, nor does the fact of distribution constitute or imply such a warranty.

Any conclusions drawn from the analysis of this information are not the responsibility of NOAA, the Office for Coastal Management or its partners

Data is available online for custom downloads

None

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be aware that temporal changes may have occurred since this data set was collected and some parts of this data may no longer represent actual surface conditions.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.

Horizontal positional accuracy for LiDAR is dependent upon the quality of the GPS/INS solution, sensor calibration and ground conditions at the time of data capture. The standard system results for horizontal accuracy meet or exceed the project specified 0.6 meter RMSE. Qualitative value: 0.6, Test that produced the valued: This value is computed by comparing ground control to an intensity based image derived from the classified LiDAR data and represents the RMSE of residuals on controls within the project area.

Vertical accuracy requirements for the Harford County lidar project are defined as sufficient to support 2' contour or RMS = to 1/2 of the 2' contour interval (0.67') for well defined points. Vertical positional accuracy for LiDAR is dependent upon the quality of the GPS/INS solution, sensor calibration and ground conditions at the time of data capture. The lidar capture was composed of 3 separate flight missions on 2 separate dates . Lines 18-30 and lines 31-40 flown 20130309 and lines 1-17 flown 20130406. Each of the 3 flight missions was post processed and classified as separate blocks and then combined vertical accuracy statistics developed for the entire data set. The vertical accuracy of the bare earth lidar DEM, utilizing 22 well defined control points in the project area, was tested with a resultant RMSE of 0.223'.Qualitative value:0.223, Test that produced the value: Meeting the vertical accuracy requirement is ensured by comparing ground control elevation to the classified LiDAR ground surface. The project-wide RMSE is calculated from the vertical differences between surveyed ground control and the bare earth lidar surface and represents the RMSE on controls within the project area.

LiDAR data is collected for the project area. Post processing of the simultaneously acquired GPS/INS is performed and applied to the laser returns to output a point cloud in the specified project coordinate system and datums. The point cloud data is then subjected to automated classification routines to assign all points in the point cloud to ground, water, overlap and unclassified point classes. Anomalous laser returns that occur infrequently are removed entirely from the data set. The ground class points are then compared to surveyed ground control to develop an accuracy measure of the laser terrain data.

LiDAR data is collected within the project area, processed and verified against control.