High frame rate image sequence from the Tanana River, Alaska, July 24, 2019, for Particle Image Velocimetry
Dates
Acquisition
2019-07-24
Citation
Legleiter, C.J., and Kinzel, P.J., 2020, Field measurements of flow velocity and optical image sequences acquired from the Salcha and Tanana Rivers in Alaska in 2018 and 2019 and used for particle image velocimetry (PIV): U.S. Geological Survey data release, https://doi.org/10.5066/P9IJ20O4.
Summary
This data release consists of a sequence of optical images extracted from a high frame rate video and used to derive remotely sensed estimates of surface flow velocity via particle image velocimetry (PIV). These data were acquired from the Tanana River near Nenana, Alaska, on July 24, 2019, along with field measurements of flow velocity used to assess the accuracy of image-derived velocity estimates. The images were obtained using a Zenmuse X5 video camera deployed within a Meeker mount attached to the nose of a Robinson R44 helicopter. The original video was recorded at 30 frames per second while the helicopter hovered in a fixed location approximately 600 m above the river, but the image sequence was extracted at a rate of 10 [...]
Summary
This data release consists of a sequence of optical images extracted from a high frame rate video and used to derive remotely sensed estimates of surface flow velocity via particle image velocimetry (PIV). These data were acquired from the Tanana River near Nenana, Alaska, on July 24, 2019, along with field measurements of flow velocity used to assess the accuracy of image-derived velocity estimates. The images were obtained using a Zenmuse X5 video camera deployed within a Meeker mount attached to the nose of a Robinson R44 helicopter. The original video was recorded at 30 frames per second while the helicopter hovered in a fixed location approximately 600 m above the river, but the image sequence was extracted at a rate of 10 frames per second (10 Hz). The original images were not geo-referenced and had to be stabilized to account for motion of the helicopter platform during acquisition. Image stabilization was performed using the TrakEM2 plugin to the ImageJ software package. The stablized image sequence was then geo-referenced in the Global Mapper software package using tie points selected from an online satellite image accessed through Global Mapper as well as surveyed ground control targets placed in the field and visible within the images. A spatial transformation based on these tie points and control points was derived in MATLAB and then applied to the images to project them into the UTM Zone 6N, NAD83 coordinate system. The resulting geo-referenced images had a spatial resolution (pixel size) of 0.15 m and effectively stabilized the image sequence prior to PIV analysis. The images were converted to grayscale and saved as TIF files with corresponding world files (*.tfw) that contain the spatial referencing information for each image. The sequence consists of 685 individual images representing over one minute of data collection. The entire sequence of TIF images and worldfiles is contained within a zip archive.
For questions concerning this data set, please contact:
Dr. Carl J. Legleiter - cjl@usgs.gov, 303-271-3651
Geomorphology and Sediment Transport Laboratory
United States Geological Survey
4620 Technology Drive, Suite #400
Golden, CO 80403
Purpose
The purpose of this study was to assess the feasibility of inferring flow velocities from optical image sequences acquired from a helicopter hovering above the river by tracking water surface features via Particle Image Velocimetry (PIV) and to develop a modular workflow for performing this type of analysis. Remote sensing of flow velocity could provide a more efficient, cost-effective alternative to conventional field-based methods of measuring velocity and thus become an important component of non-contact approaches to streamgaging. Along with field measurements of flow velocity used for accuracy assessment, these data were used to assess the potential to estimate surface flow velocities in sediment-laden rivers from helicopter-based, hovering image sequences using particle image velocimetry (PIV) techniques.
Rights
Any use of trade, firm, or product names is for descriptive purposes only and does not imply endorsement by the U.S. Government.
Preview Image
Example image extracted from video of the Tanana River used to perform PIV.