Current UAV Payloads Owned by GRI and NGI
March 12, 2014
As most of you that have operated UAS know, there are quite a few choices when it comes to payloads: RGB, CIR, lasers, hyperspectral imagers, the works. Of course, depending on your UAS carrying capacity and energy constraints, you might not be able to utilize the spectrum of imagers available.
This is the current case with our operations. Mississippi State University currently owns two birds: the Altavian Nova, a roughly 11 pound bird that can carry up to 3 pounds, and the Robota Triton, a 3 pound payload that is much more limited.
We currently have three payloads in use for these UAS.
Altavian Non-Metric Mapping Payload
The Nova uses a non-metric payload, which consists of a Canon EOS T2i camera coupled with a Xsens GPS-Aided AHRS for direct georeferencing. The effective resolution is 18 megapixels (5184x3456).
In the current setup, the field-of-view is approximately 31.42 x 21.24 degrees.
Currently, this camera only captures in the visible spectrum (RGB). Modifications are being investigated, however, to capture blue, green, and near-infrared instead.
The payload is also capable of capturing images at a rate of better than an image per second.
Robota Triton RGB Mapping Payload
The Triton payload consists of a compact Sony RX100 camera at a resolution of 20 megapixels. It is not currently tied into its own GPS, instead utilizing the same GPS readings as the autopilot system.
Note that while the camera has a better overall resolution than the Nova payload, it is not a DSLR, which means that the data quality does not match that of the Nova payload, and the larger field-of-view means that per-pixel GSD is not as high, either.
The Triton takes images at roughly four seconds per image, although this number may be reduced a bit.
Tetracam ADC Lite
The ADC Lite is used in quite a few small UAS applications. It captures imagery that approximates Landsat bands 2, 3, and 4 (green, red, and near-infrared) at a resolution of 3 megapixels.
Some of the tradeoffs with this camera are the lack of storage (only 2GB maximum) and the imaging frequency. The best mode for storage and data quality is 10-bit DCM, but this limits the imaging frequency to roughly seven seconds. The 10-bit RAW mode is better, but takes up significantly more space, leading to very quickly filling up the Compact Flash card when taking images at the allowable rate of five per second. The last mode, 8-bit RAW, gives better capability to store images, but also reduces the granularity of each pixel's value, from 1024 possible values to only 256 per band.
A rough breakdown of ground sample distance (GSD) per pixel is given in the table below.
||Field-of-View (WxH, deg, in-track)
||GSD @ 400 ft AGL (in)
||5184 x 3456
||21.24 x 31.42
||5472 x 3648
||32.45 x 48
|Tetracam ADC Lite
||2048 x 1536
||34.18 x 44.52