THERMAL-VISUAL DIGITAL SYSTEM IN THE IMAGE OF AREA PHENOMENA
Andrzej Lubecki*, Bogustaw Wiecek**
* Chair of Photogrammetry and Remote Sensing
Olsztyn Uniwersity of Agriculture and Technology-Poland
**Institute of Elektronics
Technical University of Lódz-Poland
Commision |, Working group 3
KEY WORDS: Thermal camera, CCD, Computer, Image, Infrared, Remote sensing.
ABSTRACT
Thermal-vision digital system (TVDS) was worked out on the basis of a thermal scanner of AGEMA LWB 880 and vi-
sion camera CCD. The scanner obtains data in spectrum range 8-12 um and the camera CCD in the range 0,4- 0,9
um. The aim of the system is to register digital data on surface temperatures distribution and their measurements on
the examined objects. Generated thermal and visual images are stored in the computer memory IBM notebook type
and processed on one monitor in parallel. The systemcan work on different stands in a laboratory, in a car while
driving or in a plane during a flight. TVDS may register thermal images, visual images or both of them: a) as single i-
mages, b) as films with given time intervals between registration of particular records, C) in real-time. The registered
digital images undergo elaboration taking into account surrounding temperature, emission coefficient and registration
distance (atmospheric conditions). The elaboration of thermograms can be carried out in TVDS or outside it. There is
a possibility of elaborations in different forms: qualitative or quantitative ones. Graphic image has got a screen form
which can be a layer of a vector map. TVDS is an open system and therefore it can be equipped with necessary ad-
ditional applications.
1. STRUCTURE, FUNCTIONING AND SOFTWARE
TVDS
The interface of camera is an essential element of a
computer system of processing thermographic images
where analog signal carrying information concerning the
temperature of an object which is changed into digital
form and sent to a computer. The possibility of recipro-
cal matching of thermal and optical images was applied
for faster and easier interpretation of thermograms. The-
refore the system was equipped with two cameras:
thermal and CCD visual ones. The methods of pro-
cessing the images concern both thermal and optical
parts. However, they differ as far as different amount of
information in both images is concerned.
Vin
Fig.1. Operation of interface in the thermal camera dia-
gram
116
The optical systems of both cameras have got similar
parameters and software runs in Windows 3.1 and a
computer notebook type-fig.1. The thermal camera
AGEMA LWB 880 is an electromechanical device where
the process of the image analysis takes placedue to ro-
tation of prisms and mirrors. The rate of image genera-
tion by the camera is low because rotational speed of
the scaning system is limited. A low rezolution data a-
cquiring system is recommended. Typically, resolution of
256 pixels/line is quite acceptable. As a result of this re-
solution the data transmission rate (from camera to the
computer) does not exceed hundreds Kbytes per se-
cond. Synchronization system, where sampling clock
signal is produced, is a very important element of the
interface. It is the signal with much higher frequency
than horizontal HSYNC and vertikal VSYNC deflection
frequency. Accuracy of reproduction of sampling clock
influences the thermal image being transmitted to a
computer(Wiecek, B. 1993)
Another important element of TVDS is an optical inter-
face of CCD camera. The computer interface of the CCD
camera is equipped with large butter memory because
of the sizeof optical inages. It enables to store one or
few full images. The elements of preliminary digital
conversion can be additionaly found in the buffer memo-
ry. The image transmitted to the computer is of high
stability and quality as the contrast, emission coefficient
or environmental conditions are concerned. The interfa-
ce of the optical camera is presented in picture 2. High
power of interface conversion results from high calcula-
tion power of optikal image processor and the possibility
of availability to many image pixels. Low speed informa-
tion exchange through transmission circuits is limitation
of image conversion. Monochrome CCD camera intefa-
ce contains 16-bit graphic processor dedicated for
complex video operations.
International Archives of Photogrammetry and Remote Sensing. Vol. XXXI, Part B1. Vienna 1996
Fig.2
TVS-
AGE
real-
50m
real-
160r
non
real-
non
5. Tr
6. Ne
5. Li
6. Vi
7.8
