Photogrammetric Orthorectification

Job Title: Photogrammetric Orthorectification

Location: Flagstaff, AZ

Duties:

• The work involves orthorectification of approximately 400 black-and-white historical aerial images of Parker Valley, Arizona in a ‘core’ area of interest (AOI-1). There will be an option to extend the contract to additional AOIs on the Colorado River floodplain in Mohave Valley, Nevada-California (AOI-2), Palo Verde / Cibola Valley, California-Arizona (AOI-3) if pricing and additional funding allows. Each option will involve the same orthorectification of approximately 400 black-and-white historical aerial images. The key available digital aerial photo series have varying scales and span the historical period of 1930 to 1954 and digital copies of all photos will be provided to the Candidate. This first contract opportunity will focus on aerial photos from the 1930s (highest priority), 1940s (second priority), and 1950s (third priority).
• The Candidate will perform the orthorectification and mosaicking of AOI-1 in the base period of performance and there will be two options to extend the contract to AOI-2 and AOI-3 areas which is subject to pricing and availability of funds. Such options will involve the same photogrammetric orthorectifications work and include 400 black-and-white historical aerial images each.
• Final products (individual orthorectified aerial photographs and mosaics) must meet National Standard for Spatial Data Accuracy (NSSDA) criteria. (National Standard for Spatial Data Accuracy. Candidate will deliver all digital geospatial data with metadata files that comply with the Federal Geographic Data Committee and accord with data requirements of ScienceBase.
• Candidate will employ the National Standard for Spatial Data Accuracy (NSSDA) method for evaluating map accuracies. The NSSDA standard offers a means of statistically testing positional accuracy independent of map scale. The NSSDA reports accuracies as the Root Mean Square Error (RMSE) of evaluated test points for each spatial data set at the 95% confidence level.
• Simply stated, the RMSE is a measure of the difference between a set of calculated values and a set of the most probable values. These calculations are made by comparing positions of well-defined points in an independent orthorectified dataset. The Candidate will use the most recently collected National Aerial Inventory Program (NAIP) digital quarter quadrangle aerial image data as the independent dataset. The NAIP quarter quadrangle aerial images are publicly available at The USGS National Map website. These digital datasets have horizontal accuracies of 6 meters at a 95% confidence level (pre-2016) or 4 meters at a 95% confidence level (post-2016)
• Accuracy calculations will follow methods recommended by NSSDA, which states: “…accuracy is reported in ground distances at the 95% confidence level.” This means, “…95 % of the positions in the dataset will have an error with respect to true ground position that is equal to or smaller than the reported accuracy value. Accuracy calculation methods (including a downloadable spreadsheet) are provided at the NSSDA link.
•  The Candidate will submit statements of the horizontal accuracies in the terms of the RMSE thusly:
  • “Tested________feet horizontal accuracy at 95% confidence level”
• The Candidate will test for and provide report on horizontal accuracy in rectification by comparing the planimetric coordinates of well-defined, identifiable points in mosaic dataset(s) with coordinates of the same points from an independent source of higher accuracy, e.g., recent NAIP orthophotography or LiDAR datasets, each of which is available from the USGS National Map. A minimum of 20 well-distributed check points shall be tested, distributed to reflect the geographic area of interest and the distribution of error in the dataset. When 20 points are tested, the 95% confidence level 4 allows one point to fail a 3 m threshold.
• Accurately orthorectified and mosaicked photographs of 1930 and 1939 vintage as raster datasets compatible with ESRI ArcPro GIS software:
  • Photomosaics must be aesthetically pleasing, tonally balanced, seamless and developed with emphasis on least distorted photo- center regions
  • GeoTiff Format; NAD83 UTM Zone 11N
  • Feature class that defines the boundaries of photos and mosaics
  • Explanation of mosaicking method and related properties used to control the mosaicking and any derivative images
  • Seamline feature class for seamline mosaicking
• Candidate will provide Federal Geographic Data Committee (FGDC) compliant metadata for all mosaic datasets and ensure compliance with SciencBase metadata requirements.

Education & Qualifications:

• Must have proven expertise and evidence of exceptional past performance in digital photogrammetry and orthorectification of historical (early to mid-twentieth century) aerial photography in similar geologic contexts (i.e. river and floodplain).
• Candidate-provided data will be in the public domain and distributed on ScienceBase.gov.