VTT Technical Research Centre of Finland has developed a Fabry-Perot Interferometer (FPI) based hyperspectral imager
compatible with light weight UAV (Unmanned Aerial Vehicle) platforms (SPIE Proc. 74741, 8186B2). The FPI based
hyperspectral imager was used in a UAV imaging campaign for forest and agriculture tests during the summer 2011
(SPIE Proc. 81743). During these tests high spatial resolution Color-Infrared (CIR) images and hyperspectral images
were recorded on separate flights. The spectral bands of the CIR camera were 500 - 580 nm for the green band,
580 - 700 nm for the red band and 700 - 1000 nm for the near infrared band. For the summer 2012 flight campaign a new
hyperspectral imager is currently being developed. A custom made CIR camera will also be used. The system which
includes both the high spatial resolution Color-Infrared camera and a light weight hyperspectral imager can provide all
necessary data with just one UAV flight over the target area. The new UAV imaging system contains a 4 Megapixel CIR
camera which is used for the generation of the digital surface models and CIR mosaics. The hyperspectral data can be
recorded in the wavelength range 500 - 900 nm at a resolution of 10 - 30 nm at FWHM. The resolution can be selected
from approximate values of 10, 15, 20 or 30 nm at FWHM.
VTT Technical Research Centre of Finland has developed a Fabry-Perot Interferometer (FPI) based hyperspectral imager
compatible with the light weight UAV platforms. The concept of the hyperspectral imager has been published in the
SPIE Proc. 7474 and 7668. In forest and agriculture applications the recording of multispectral images at a few
wavelength bands is in most cases adequate. The possibility to calculate a digital elevation model of the forest area and
crop fields provides means to estimate the biomass and perform forest inventory. The full UAS multispectral
imaging system will consist of a high resolution false color imager and a FPI based hyperspectral imager which can be
used at resolutions from VGA (480 x 640 pixels) up to 5 Mpix at wavelength range 500 - 900 nm at user selectable
spectral resolutions in the range 10...40 nm @ FWHM. The resolution is determined by the order at which the Fabry-
Perot interferometer is used. The overlap between successive images of the false color camera is 70...80% which makes
it possible to calculate the digital elevation model of the target area. The field of view of the false color camera is
typically 80 degrees and the ground pixel size at 150 m flying altitude is around 5 cm. The field of view of the
hyperspectral imager is presently is 26 x 36 degrees and ground pixel size at 150 m flying altitude is around 3.5 cm. The
UAS system has been tried in summer 2011 in Southern Finland for the forest and agricultural areas. During the first test
campaigns the false color camera and hyperspectral imager were flown over the target areas at separate flights. The design and calibration of the hyperspectral imager will be shortly explained. The test flight campaigns on forest and crop fields and their preliminary results are also presented in this paper.
VTT Technical Research Centre of Finland has developed a lightweight Fabry-Perot interferometer based hyperspectral
imager weighting only 400 g which makes it compatible with various small UAV platforms. The concept of the
hyperspectral imager has been published in SPIE Proc. 74741 and 76682. This UAV spectral imager is capable of
recording 5 Mpix multispectral data in the wavelength range of 500 - 900 nm at resolutions of 10-40 nm,
Full-Width-Half-Maximum (FWHM). An internal memory buffer allows 16 Mpix of image data to be stored during one
image burst. The user can configure the system to take either three 5 Mpix images or up to 54 VGA resolution images
with each triggering. Each image contains data from one, two or three wavelength bands which can be separated during
post processing. This allows a maximum of 9 spectral bands to be stored in high spatial resolution mode or up to 162
spectral bands in VGA-mode during each image burst. Image data is stored in a compact flash memory card which
provides the mass storage for the imager. The field of view of the system is 26° × 36° and the ground pixel size at 150 m
flying altitude is around 40 mm in high-resolution mode. The design, calibration and test flight results will be presented.
KEYWORDS: Cameras, Sensors, Telecommunications, Chemical analysis, Safety, 3D modeling, Visualization, Optical sensors, Algorithm development, Control systems
The Second Generation Locator for Urban Search and Rescue Operations (SGL for USaR) is an EC-funded project
solving critical problems following massive destruction and large scale structural collapses in urban locations. One part
of the project is the development of a standalone portable first responder device (FIRST) for the operational rescue
teams. It will combine field chemical analysis, spectral analysis with audio and video analysis capabilities for the early
location of entrapped people, the detection of buried people and air quality monitoring in confined spaces for ensuring
safety and security of first responders.
Hardware selected for the optical sensors of the FIRST-device will be responsible for the fluorescence, visible (VIS),
near infrared (NIR) and long wavelength infrared (LWIR) range detection as well as supplying required illumination.
FIRST shall identify images of fires or other events, damage patterns, temperature of living humans, motion of body
parts and human postures. The device requirements were based on the operational input and feedback received from
European rescue teams - partners within the project (final product end-users). Some of the critical properties for the
selected components were compact physical size, low power consumption, refresh rate and adequate resolution of the
sensor image data. During the project, special image libraries were collected and suitable image processing algorithms
based on the collected data were developed.
The performance of a random target method for fast MTF measurement of a lens is evaluated. Although the method is well-known, its potential for fast lens testing has not been assessed in the open literature. To optimize speed, the simplest possible instrument setup with minimum amount of mechanical movements during measurement execution is used. The setup includes only a random target, lens under test and a CCD camera with focus adjustment. The target consists of a random black and white pattern of a flat spectrum. The MTF of the lens is acquired by imaging the random target on the CCD using the lens, and then analyzing the spatial frequency content of the image using an ordinary PC. It was found out that a suitable compromise between speed and precision is achieved using a matrix of 128*128 samples per measured field point. This provides better than 2% precision and a few second's total execution time per lens including best focus evaluation and the measurement of tangential and sagittal MTF curves of 5 field points. Using commercially available components, measurement frequencies up to 100 cycles/mm seem achievable using the simple instrument setup.
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