Research for development of small-format multi-spectral aerial photographing system
named PKNU 3
2. Application
2.1. Chronologic table of this study
This study was initiated on January 2004, and the field study, supported by the Ministry of
Maritime Affairs & Fisheries and the Korea Environmental Institute, was completed with the 2 nd
aerial photography test on September 2004. Objectives pertaining to each test are shown in the
following table 1.
Table 1 chronologic table of this study
2.2. Multi-spectral aerial photographing system named PKNU 3
PKNU 3 consists of a sensor array, data storage system and platform as shown in figure 1. The
sensor portion utilizes a REDLAKE MS 4000 multi-spectral camera and Raytheon IRPro thermal
IR camera, both supports by gimbals to prevent the vibration of the platform and allow for
adjustability of the photographic angle. The Data storage system is composed of an MPEG
board, which can compress and transfer moving pictures in real time as high quality images, and
two computers each with 120 Gigabyte memory capacities to store data in volume. The
helicopter was chosen as the aerial platform because it could fly a low-speed and rotate 360 o
thus making it able to fly in ways that fixed-wing aircraft are unable.
2.2.1. Sensor part
In the PKNU2 system had drawbacks in its ability to obtain composite 4-band images of any
particular target area because the task of photographing the color and near infrared images was
divided between the separate Kodak DCS 460 color and infrared cameras respectively. In
addition, it was difficult to control the least overlapping rate (60%) due to the 12-second interval
of storage. Therefore, the REDLAKE MS 4000 sensor was introduced to overcome this
drawback as well as provide the capability of obtaining moving picture data.
The REDLAKE MS 4000 sensor is a triple CCD camera that can take R, G, B, and IR band
images simultaneously so it can produce RGB and CIR images of the target area of 1600 ×1200
pixels (7.4 . per pixel). The light sensitivity of the camera lens is controllable using gain
values and an electronic shutter. The thermal infrared camera, a Raytheon IRPro, used in this
study, senses the energy of the 7~14 . wavelength as still and moving pictures and displays
through an LCD viewer. Distribution of thermal energy in images can be displayed through
the use of 5 colors (red, orange, yellow, green, and blue) and temperatures be shown in terms of
brightness values. These two cameras (REDLAKE MS 4000 & Raytheon IRPro) are mounted
on gimbals specially designed to prevent platform vibration as well as provide a wide
adjustability of the photography angle. While the MS4000 has automatic focus ability, the
thermal IR camera does not; therefore, a separate unit to remotely control the thermal IR
camera's focus was added to the gimbals/camera assembly.
2.2.2. Data Storage system
A high capacity data storage system is necessary record the volumes of images due to the 1
second data storage time of MS 4000. Two compact computers of 120 Gigabyte storage
capacities with a 12-volt power supply were implemented for the data storage system because
the PKNU 3 depends on onboard power of the aerial platform. The two computers are tightly
packaged in a special case that insulates from the vibration energy of the helicopter platform.
To further reduce vibration, a wiring harness was implemented that consolidates every connector
between the sensor components and the data storage system as one thick cable.
2.2.3. GPS
A GPS antenna was included with PKNU 3 to compute the flight course, flight velocity, and
altitude of aerial platform as well as provide 3 dimensional coordinates of each exposure station
(x, y, z), and rotation angle of platform , . , K ) for exterior orientation.
