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Preparing for Photogrammetric Data Processing

August 2016

With an ever-growing landscape of photogrammetric software solutions, Altavian strives to build payloads which are compatible with as many software packages as possible. This article provides a detailed look at the logic and file structures of Fusion MP22 series payloads, outlining the location and formats of all information required for photogrammetric data processing.

Fusion MP22 Data Logic

Each time a Fusion MP22 series payload is started, a new folder is created on its internal hard drive with the following naming convention:

Root:/DATA/YYYY-MM-DD-HH-MM-SS_MODEL_SERIAL (In Coordinated Universal Time)

Contained within each directory is:

  • Every image captured throughout the flight
  • Text files for performance troubleshooting
  • A ‘nav.txt’ file containing each image’s positional data in the following format: ImageName,TimeStamp(SecondsOfWeek),Latitude,Longitude,Altitude,Roll,Pitch,Yaw

nav.txt file

In addition to the nav.txt file, GPS data is also written directly to each image’s EXIF tags (embedded metadata fields inside of image files). The nav.txt file is used for programs that cannot read custom EXIF values (such as INS) and for dataset management in Flight Visualizer.
 

GPS / INS Conventions

 
GPS values are represented in Latitude and Longitude using WGS84 decimal degrees.

Altitude values are represented in meters ‘MSL’, as defined by WGS84 ellipsoidal height with EGM96 undulation.

INS values (roll, pitch, yaw) are represented in degrees relative to North.

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