2018 NOAA NGS Ortho-rectified 4 band Mosaic of Lexington Park, MD

This orthoimagery data set includes 30-cm 8-bit 4-band (RGBNIR) digital orthomosaics in GeoTIFF format. Geographic Extent: A multipart AOI covering approximately 463 total square miles of Maryland and Virginia along the coastline of the Chesapeake Bay. Dataset Description: The NOAA Chesapeake Bay Topobathy 2018 Orthoimagery Project called for the planning, acquisition, processing, and derivative products of imagery data to be collected at a ground sample distance (GSD) of 30 centimeters. Project specifications are based on the American Society of Photogrammetry and Remote Sensing (ASPRS) standards. The data were developed based on a horizontal projection/datum of NAD83 (2011), UTM Zone 18N, Meters. Imagery data were formatted to 325 individual 3,000-meter x 3,000-meter orthomosaic tiles and 539 uncompressed stereo images. Ground Conditions: Imagery was collected in spring and summer of 2018, while no snow was on the ground and rivers were at or below normal levels.

Ortho-rectified mosaic tiles are an ancillary product of NOAA's Coastal Mapping Program (CMP), created through a wider Integrated Ocean and Coastal Mapping initiative to increase support for multiple uses of the data.

The ground sample distance (GSD) for each pixel is 0.30 m.

Users must assume responsibility to determine the usability of these data. These photographs were obtained for use by NGS during the course of its development of potential final products to fulfill its statutory mission. Although NGS is making these photographs available to others who may find the photographs of value, NGS does not warrant, endorse, or recommend the use of these photographs for any given purpose. NGS is providing these photographs "as is," and NGS disclaims any and all warranties, whether expressed or implied, including (without limitation) any implied warranties of merchantability or fitness for a particular purpose. In no event will NGS be liable to you or any third party for any direct, indirect, incidental, consequential, special, or exemplary damages or lost profits resulting from any use or misuse of these data. 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.

OS Independent

The project specifications require that only horizontal accuracy be computed for orthoimagery files. The required accuracy meets or exceeds the ASPRS Class I Accuracy standards for 1" = 200' maps, derived according to the latest ASPRS standards. The horizontal accuracy was based on the use of the airborne GIS and IMU flown in a process of precise point positioning (PPP). Control was taken from existing orthoimagery, and accuracy was determined relative to the provided orthoimagery. Accuracy has been tested to meet 2 feet(0.6 meter) or better RMSE using ASPRS Class I Accuracy Standards.

Tested 0.254 meter RMSEx as defined by the ASPRS Class 1 Accuracy Standards for 1" = 200' maps.

Tested 0.142 meter RMSEy as defined by the ASPRS Class 1 Accuracy Standards for 1" = 200' maps

Tested 0.291 meter RMSEh as defined by the ASPRS Class 1 Accuracy Standards for 1" = 200' maps.

All GeoTIFF tagged data and image file sizes are validated using commercial GIS software to ensure proper loading before being archived. This validation procedure ensures correct physical format and field values for tagged elements. Seamlines and tile edges are visually inspected. Seamline mismatches are corrected unless the overall displacement is less than one pixel.

Orthoimages are visually inspected for completeness to ensure that no gaps or image misplacements exist within and between adjacent images. These images are derived by mosaicing multiple images to ensure complete coverage. Source imagery is cloud free.

The extent of image coverage is limited to the acquired flight lines which were planned to map the shoreline and therefore may not include all areas within the bounding coordinates.