Two-Endmembers Three-Endmembers 
  
(20) (100) 
GV + SHD GV + N/SA + SHD 
N/S/1 + SHD GV + W1 + SHD 
WI + SHD GV + W2 + SHD 
W2 + SHD N/S/1 + W1 + SHD 
N/SA + W2 + SHD 
W1 + W2 + SHD 
  
  
Four-Endmembers 
(500) 
GV + N/S/ + W1 + SHD 
GV + N/S/T + W2 + SHD 
GV + WI1 + W2 + SHD 
N/S/ + W1 + W2 + SHD 
  
  
Table 3. Endmember combinations 
four-EM models as 0.6% in reflectance respectively. After the 
shade fractions were normalized, land cover class accuracy was 
assessed using 80 sample pixels of field records (20 per EM 
land cover class). 
6. RESULTS AND DISCUSSION 
6.1 Input data combinations for ESTARFM 
The AADs between the observed and blended reflectance for 
the input combinations that achieved highest mean values of 
AADs in all spectral bands on each target date are shown in 
Table 4. The three alphabet codes stand for the input 
combinations. Each alphabet in the codes corresponds to 
observation dates as summarized in Table 1. The first and third 
lower alphabets refer to the prior and posterior dates, and 
second upper alphabets refer to the target dates. Therefore, one 
TM and one MODIS images were utilized on the dates denoted 
by lower case letters, while one MODIS image was utilized on 
the dates denoted by upper case letters. 
The tests of all input combinations demonstrated that 
ESTARFM did not always obtain strong agreement when the 
prior and posterior dates are closer to the target dates. This fact 
suggested that the correlation between the observed and 
blended reflectance may have depended on other environmental 
factors in the study area, such as phenological stage of the 
wetland vegetation and water level of the lake. The difference 
between observed and blended reflectance was generally larger 
in the spectral bands with longer wavelengths, such as near- 
infrared (NIR), shorter and longer shortwave infrared (SWIR) 
bands. Larger differences were found particularly in the visible 
blue and NIR bands when the input reflectance with cloud 
contamination was utilized to blend the reflectance. 
6.2 Applicability of MESMA to blended data 
6.2.1 Percentages of modeled pixels: The percentages of 
pixels modeled by MESMA for the observed and blended 
reflectance data is shown in Figure 2. All three cases using the 
observed reflectance data (Cases 1, 3, and 5) achieved high 
percentages of modeled pixels (higher than 89%) except for 
Case 3 on September 13, 2005. However, many pixels in the 
blended data could not be unmixed by other three cases (Cases 
2, 4, 6), particularly on August 12 and September 13 in 2005. 
International Archives of the Photogrammetry, Remote Sensing and Spatial Information Sciences, Volume XXXIX-B8, 2012 
XXII ISPRS Congress, 25 August — 01 September 2012, Melbourne, Australia 
  
  
  
  
  
  
  
  
  
  
  
  
  
  
  
  
  
Tae Combination| Blue | Green | Red 
date 
2004/10/28 aBd 1.06] 126} 1.38 
2004/11/29 bCd 105, 153] 1.52 
2004/12/15 cDh 1.441 1.86| 1.87 
2005/3/5 dEh 2.68| 2.07| 1.89 
2005/8/12 aFg 3.10] 3.00] 2.65 
2005/9/13 fGh 3.68| 3.58| 3.08 
2005/9/29 aHi 1.5G| 157) 2.05 
Target Shorter | Longer 
date NIE: | sw { sw | M0 
2004/10/28 3.771 4.26] 3.23] 2.49 
2004/11/29 2.39| 3.03] 2.46] 2.00 
2004/12/15 2.48] 3.65] 2.84] 2.36 
2005/3/5 300] 4.257 3.23| 2.87 
2005/8/12 4.81 2.60] 2.90| 3.18 
2005/9/13 554 385) 226| 367 
2005/9/29 4.19| 329° 2.74] 2.56 
  
  
  
  
  
  
* Unit: 96 of reflectance 
Table 4. Average absolute differences between the observed and 
blended reflectance for best input combinations 
100 * 
95. - 
90 
85: 
80 - 
75 
70 
   
  
Percentage of modeled pixels 
  
> x $ & o $ 
S S S S S S 
+ S uS a 
SS N A> WY N 
sellos Cas el "+= Case 2 
ws op « Case 3 = @ = Case4 
mee Case 5 —X- = Case 6 
Figure 2. Percentages of modeled pixels in the MESMA of 
observed and blended reflectance data 
This is mainly because the input blended data for those dates 
had larger differences in reflectance from the observed data in 
the blue, green, read and NIR bands than the blended 
reflectance for other dates. It led to the RMSEs larger than the 
modeling threshold (2.5% reflectance) in all EM models. For 
each comparison, the cases for the observed data reached higher 
percentage of modeled pixels than those for the blended data, 
except for in the Comparison 1 on March 5, 2005 and 
Comparison 2 on September 29, 2005. Although no significant 
difference in the percentage of modeled pixels was found 
among the three cases for blended data, differences in the 
percentage of modeled pixels (larger than 5%) were confirmed 
among the three cases for observed data on August 12 and 
September 13 in 2005, suggesting that the differences were 
brought by the inclusion of EM spectra on different dates and 
data sources (observed, blended or both reflectance). 
     
  
    
   
      
     
   
      
    
  
    
   
     
   
   
    
   
   
   
     
    
   
   
   
   
   
    
  
   
  
    
Int 
Kappa coefficient 
Kappa coefficient 
Figu 
6.2.2 
kapp: 
EM c 
blend 
coeffi 
accur 
confu 
broug 
reflec 
betwe 
under 
to tk 
value 
data) 
dates, 
dates. 
data 
in Cc 
Septe 
5, Au 
the d 
comp 
coeffi 
2004, 
obser 
value 
optim 
and 6 
dates. 
differ 
6.2.3 
LCFs 
summ 
case 
W2 1 
three