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International Archives of the Photogrammetry, Remote Sensing and Spatial Information Sciences, Vol XXXV, Part B7. Istanbul 2004
Figure 9. Thermal (a) and hyperspectral (b) images of Fuchu
Figure 10 illustrates three kinds of spectrums generated from
the hyperspectral data for several buildings, which were
selected for the buildings of the higher temperature (higher than
36° 9, middle temperature buildings (15* to 36* 3, lower
temperature buildings (lower than 15* 3. Although there is not
much characteristic differences in the reflectance patterns, we
noticed the differences in the digital number (DN) values
(reflective intensity).
Figure 11 (a) describes the relationship between intensity of
reflection estimated from the hyperspectral data and the
temperature observed by the TABI. It indicated that the ground
surface temperature became lower, as intensity of reflection
became higher. We also analysed the airborne surface
temperature data captured for the Osaka City. The observation
was performed on 11* September 2003 at 16:45 and 141
September 2003 at 23:30hrs. The intensity of reflectance was
estimated by the visible data (Red: 610-660nm, Green:
535-585nm, Blue: 430-490nm) and the NIR data (835-885nm)
captured by airborne digital sensor (ADS40, GSD of 20cm) in
August 2003, because the hyperspectral data was unavailable
for that duration.
Values in Figure 11 (b) illustrate the relationship between
intensity of reflection observed from ADS40 and ground
surface temperature of the evening acquired by TABI. It
indicates that ground surface temperature becomes low, as
intensity of the reflection reaches higher values. Similarly, the
plotted values in Figure 11 (c) shows the relationship between
intensity of reflection (from the ADS40 image) and ground
surface temperature in the midnight. It indicates that there is no
relationship between the ground surface temperature and
intensity of reflection. This was obviously because there was
no solar radiation energy during the nighttime.
7. SUMMARY AND FUTURE WORK
We observed the surface temperature in Hiroshima City used
by airborne sensor, gh September 2003, between
17:00-18:00hrs. It showed that the road temperature was higher
than river and forest temperature about 12°C. The surface
temperatures of the business district areas had almost same
temperatures as bare soils and higher than river and forest
about 7°C.
47
x 10°
6 High temperature buildings
5 29
DN Value
DN Value
ture buildin
Lowt
404 489 575 664 754 845 936
Wavelength (nm)
Figure 10. Differences in the spectrums by radiometric surface
temperature
$ Correlation |
45 3.9 — Coeffiient -0.72. i
g 3S
Be
E o 30
= 5
BE
=
& 3 2s |
LE |
u 5 |
En . |
=
15
0 5 10 15 207 25
Total of DN value x 107
36 —— ——————XÀ 1
Correlation |
= — 24 Coefficient: -0.48 |
= 3
E. e
Ev 2$ * e
28
= 5 32 4. = ©. i
e n * |
BE * 6 e?
= 0 *
= + 30 i
= |
= i
28 J
0 2 4 6 8 10
Total of DN value x10?
30 p—————————————7]
Correlation |
e Coefficient : 0.11 |
2 IR — a es e AI NA
= 28 se e |
© + e +? |
22 rer AS |
= 3 26 e * |
5 9. |
2
3E d |
uo 24 F———————— 5 - =
m Ust {
=
7 5 -i
== 2 4 6 8 10
Total of DN value x 10°
Figure 11. Relationship between reflectance and Ground
surface temperature. (a) Fuchu City (b) Osaka City - evening
time observations (c) Osaka City - midnight observations
After comparing the hyperspectral data with the temperature of
the building-roofs, there were noticeable differences in the
spectrum for the surface temperatures. There were not many
characteristic differences in the reflectance patterns, but the
differences were noticed for the DN values. The reflectance of
the material between 400 to 970nm and surface temperature
had the negative correlations. The present conducted study will
