2019 NOAA NGS 4-band Ortho-rectified Mosaic of Chesapeake Bay (Gwynn to Newport News, VA)

This orthoimagery data set includes 0.3 meter 8-bit 4-band (RGB-IR) digital orthoimage tiles in GeoTIFF format. Geographic Extent: 7 counties in Maryland, covering approximately 569 total square miles. Dataset Description: The Chesapeake Bay NOAA Option 3 project called for the planning, acquisition, processing, and derivative products of imagery data to be collected at a ground sample distance (GSD) of 0.3 meter. 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 NAD1983 2011 UTM Zone 18N, Meter. Orthoimagery data were delivered in 164 individual 3000 m x 3000 m tiles as 0.3 meter 8-bit 4-band (RGB-IR) orthophoto tiles in GeoTIFF format.

Ground Conditions: Imagery was collected in fall 2018 and spring 2019, while no snow was on the ground and rivers were at or below normal levels. In order to post process the imagery data to meet task order specifications and meet ASPRS horizontal accuracy guidelines, Quantum Spatial, Inc. utilized a total of 3 ground control points to assess the horizontal accuracy of the data.

These data depict geographic features on the surface of the earth. The dataset was created to current imagery data for Maryland.

Project VA1901-TB-Imagery

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 ASPRS standards. The horizontal accuracy was tested with 3 checkpoints located throughout the project area. These checkpoints were not used in the calibration or post-processing of the imagery data. The checkpoints were distributed throughout the project area and were surveyed using GPS techniques. See survey report for additional survey methodologies. The x and y positions of where the checkpoints fell on the orthoimagery were collected. These values were then compared to the surveyed control point x and y values

Qualitative value: Tested 0.154 meters RMSEx. The RMSEx of the imagery was calculated using 3 checkpoints. Tested 0.195 meters RMSEy. The RMSEy of the imagery was calculated using 3 checkpoints. Tested 0.249 meters RMSEr. The RMSEr of the imagery was calculated using 3 checkpoints.

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 mosaicking 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.

Radiometry is verified by visual inspection of the digital orthophoto. Slight systematic radiometric differences may exist between adjacent orthoimage files; these are due primarily to differences in source image capture dates and sun angles along flight lines. These differences can be observed in an image's general lightness or darkness when it is compared to adjacent orthoimage file coverages. Tonal balancing may be performed over a group of images during the mosaicking process which may serve to lighten or darken adjacent images for better color tone matching

Aerial imagery was acquired using a UltraCam Eagle camera with a flight design that included a total of 10 flight lines. Aerial imagery was supplemented with the simultaneous acquisition of airborne GPS/IMU data, which captured the ground coordinate for the nadir point of each photograph. Aerial imagery was exposed at an altitude of 13100 feet above mean terrain. Softcopy aerotriangulation was performed utilizing the airborne GPS/IMU data, GPS ground control and image coordinate measurements allowing the direct computation of the exterior orientation parameters for each image of the project. A compilation of topographic land form elevation datasets developed using in-house LiDAR data and data from the National Elevation Dataset for use in developing digital ortho imagery. Quantum Spatial performed a geodetic control survey in support of the digital orthophoto production project. A total of 3 points were used for QC testing.