Hyperspectral Mapping with the ULTRIS 20
Cubert’s newest hyperspectral video camera, the ULTRIS 20, is most suited for UAV mapping. Since it comes with a much higher spatial resolution of 400×400 pixel (spectral camera), each covering 100 spectral bands, an additional panchromatic camera is not needed to provide enough spatial information that is needed to stitch the single image cubes. Preparing the camera prior to start the UAV usually takes less then 15 minutes. Connect all parts, start the software, do a white calibration to adapt the system to the current light conditions – that’s all you need to do. GPS data is stored with each image cube full automatically.
- Area: Markbronn, Southern Germany
- Acquisition Date: May 08th, 2020
- Flight Height: 35m
- Ground Sampling Distance (GSD): 5.5cm / pixel
- Integration time: 3.8 ms
- Image Overlap: 80%/70%
- Number of single snapshot images: 188
The image below shows a Colored Infrared (CIR) from a rural area with winter wheat and rapeseed.
Hyperspectral Mapping with the FireflEYE 185
The FireflEYE 185 is a hyperspectral snapshot camera that takes the complete data cube within one blink of an eye. In sunny conditions the necessary integration time varies around 1ms. The 185 comes with 125 spectral bands covering 450-950 nm, and it weighs 490 g. This makes it most suitable to be used on UAVs. Together with cables and mini computer the payload is still less than 1kg. If attached with its customized two-axis gimbal the overall payload weight is 1.7 kg, allowing it to mount the camera on most of commercially available UAVs.
The FireflEYE 185 integrates two sensors:
- The spectral camera, resolution 50×50 pixel, 125 bands
- The panchromatic camera, resolution 1000×1000 pixel (1 MPixel), 1 band
The panchromatic camera is used to increase the spatial resolution of the camera, as it allows a pansharpening on the data, resulting in hyperspectral data cubes with a size of up to 1000x1000x125. As resampling methods you can choose nearest neighbor and bicubic.
We offer several lenses with different Field of View. Usually we recommend going for the 10mm (30° FOV) or 16mm (20°), because of the resulting larger area size per snapshot image.
The table gives an overview on the influence of lens/FOV and flight height to the spatial resolution of each pixel, for both camera sensors of the 185.
When programming your UAV with a waypoint mission consider enough overlap between the single snapshots (60-80% in both directions). This makes it easier to stitch the images to one hyperspectral mosaic. Together with the implemented GPS the panchromatic camera provides enough information for a stitching software such as Pix4D or Agisoft Photoscan to generate the mosaic. An additional IMU is not needed.
Furthermore, stitching the snapshot images not only provides a hyperspectral map, but also a orthomosaic and a Digital Surface Model as side products.
Flexibility in choosing the UAV Platform
The FireflEYE 185 is not bound to be used onboard a multicopter system, it can also be attached on a fixed wing system. The image below shows an example from an aerial survey in China taken with a Firefl<font color=#CC0605>EYE</font> 185, the image shows a hyperspectral NDVI.
- Platform: VTOL JOUAV CW-10 (hybrid UAV fixed wing / multicopter)
- Flight height: 180m
- Flight speed: 22-24 m/s
- Lens: 10mm
- Integration time: 3ms
- Overlap: 60%
- Overall file size: 30GB
- Stitching software: Agisoft Photoscan
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