International Archives of the Photogrammetry, Remote Sensing and Spatial Information Sciences, Vol XXXV, Part B7. Istanbul 2004
Mo my In» m3 my mg mg m7 Mg Mo
50657 | 3809 520 165 | 118 68 63. [614 331 43
Table 1. The LSE of 10 iterations by UFCLS
The six endmembers formed an endmember signature matrix.
Then we plugged the endmember signature matrix into (1) to
estimate the abundance fractions of the six endmembers using
FCLS algorithm for all pixel vectors in the subscene image. The
results are shown in Fig.3, where the larger the abundance
fractions are, the higher the brightness are shown in the gray
scale image, and the smaller the abundance fractions are, the
lower the brightness are shown. We know the six endmembers
were extracted without prior knowledge from the image using
UFCLS method, so which materials can they not be identified
to be without true data of the land cover. However we can
judge the m, endmember to be vegetation directly from the
pseudo color image. In order to verify the results, we compare
the classification image of vegetation in Fig. 4(a), i.e., the
abundance fractions image of m3, with NDVI in Fig. 4(b). It is
shown that the pixel classification image of vegetation agrees
significantly with the NDVI image, but the contrast of the
former is a little larger than that of the latter, so there is lack of
the information of details and edges. It is because the values
shown in the two images have different physical meanings, the
former denotes the abundance fractions of vegetation, the latter
denotes NDVI, which are generally larger than 0 even under the
circumstance of non-vegetation. And it is also shown, in Fig.
4(a) denoted by the circle, that the shade areas were not
classified correctly.
(a)m,(UFCLS) (b)NDVI
(c) m; (CSMA)
Figure 4. The effects of the classification of m;(UFCLS) and
m; (CSMA) compared to NDVI
4.2 Experiment 2
The data considered in this section are TM data with seven
bands from Landsat 5, which were obtained on 19 July 1991
located in WRS123/039. Here we selected six bands
excluding thermal infrared region. Firstly, the scene was
corrected geometrically and registered. A subscene of size
512x512 pixels, larger than the area in experiment 1, was
selected from Chibi County, Hubei Province in China for study.
A map showing the location of the study area is presented in
Fig.5. The color composite image of the study area, of raw
bands 4, 3 and 2 in red, green and blue respectively, is shown in
Fig.6.
Figure 5. Location of study area in Chibi County, Hubei
Province
Figure 6. The color composite image of the study area
We applied the same UFCLS method in experiment 1 to
process the data of the study area. Ten endmembers were
extracted from the subscene. The classification image of
vegetation, or the abundance fractions image of vegetation
endmember, is presented in Fig.7. In the same way, we
compare the classification image of vegetation with NDVI,
shown in Fig.8. There are the same results with experiment |.
Furthermore, we find that the pixel classification image of
vegetation agrees much more with the color composite image of
raw bands 4, 3 and 2 in red, green and blue respectively in Fig.6,
in which the red area generally denotes vegetation cover, than
with the NDVI image. For example, the A region of rectangle
in Fig.7 maybe had less vegetation than its surrounding region,
which is seen clearly in Fig.6 than in Fig. 8. The B and C
region of rectangle in Fig.7 are shown nearly in black, that
indicates there were not vegetations in the regions, but in Fig.8
we can not find the result. The same regions are shown in close
to turquoise in Fig.6. We know in this color composite image a
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