The International Archives of the Photogrammetry, Remote Sensing and Spatial Information Sciences. Vol. XXXVII. Part B7. Beijing 2008 
were sited according to historical records. Taking the ancient 
capitals as centers, there are abundant ancient cultural relics 
distributed from Huxian county in the west to Weiqu of 
Chang’an county in the east and from Qinlin mountain in the 
south to Xianyang loess tableland in the north (Zhu 1998). This 
area belongs to alluvial and diluvial plains of Wei River and 
Feng River, and Quaternary strata are well distributed, of which 
the thickness is about 800 meters. Along Feng River banks, 
even though long archaeological investigations have been 
carried out with traditional archaeological methods since 1931, 
little information has been acquired about this area because of 
geological and geo-morphological restrictions and longtime 
human reclamation and cultivation activities. 
According to researches of archeologists from National 
Historical Museum of China and Archeological Institute of 
Shaanxi Province, loess tablelands of Shenhe tableland and 
Xiliu tableland are located at the highest height in the area, with 
the altitude of about 440~580m, and the depth of groundwater 
table is about 20 ~ 50m, which were suitable for tomb 
construction by ancestors. Therefore, the research took the 
surrounding area of Renjiazhai village and Xiangji temple 
village and Jiali Village in Shenhe loess tableland as an 
experimental area. See figure 1. 
2. RESEARCH METHODS AND RESULTS 
The relationships between surface spectral reflectance and 
ground temperature, soil moisture and ingredients of soil are 
firstly determined by field measurements. And secondly the 
links of vegetation growth, soil ingredients, and soil structure 
changes to the characteristics of hyperspectral image are 
summarized. Simultaneous field measurements of ground 
spectrum, thermal infrared temperature, and soil moisture are 
required to determine the thermal radiation and temperature 
characteristics of nighttime and daytime hyperspectral images. 
Thirdly, endeavoring to analyze and interpret temperature, soil 
moisture and ingredients anomalies from hyperspectral images 
in the research areas combined with historical and cultural relics 
knowledges is key research work, because we can possibly get 
lots of anomaly areas worth doing further research. Finally, 
field boring exploration and historical analysis that eliminate 
false anomalies can verify the anomaly areas. 
1.2 Data Acquisition 
2.1.1 2.2.1 Visible and Short Wave Infrared Image 
Processing 
1) Spectral Angle Mapping—SAM 
In N dimensional space (N bands), pixel classification is 
decided by similarity of image pixel spectrum and the reference. 
Regarding the spectral responses of N bands as N dimensional 
space vectors, the spectral angle from a pixel to the endmember 
represents the matching level, smaller angle means more similar. 
See Figure 2, and the calculation formula is (1). 
0 - cos 
( 
\ 
-> 
t • 
r 
- cos 1 
-> 
—» 
V 
t 
r 
) 
nb 
/=1 
(nb \' l2 (nb \ 1/2 
I'. 2 Z r < 2 
V ,•=i ) v »=i / 
where 0= spectral angle 
nb = total bands used in SAM 
t = spectrum of unknown objects (to be classified) 
r = reference spectrum (known object) 
i = number of bands used 
2) Linear Spectral Unmixing 
Usually, there is not a sole object in one pixel of remote sensing 
image because spatial sampling interval is larger than ground 
objects during remote sensing scanning. Linear spectral 
unmixing is used to estimate the percentage of components in 
one pixel. 
OMISII spectrometer developed by Shanghai Institute of 
Technical Physics, Chinese Academy of Sciences was applied 
for hyperspectral scanning. There are 68 bands from visible, 
near infrared, short wave infrared to thermal infrared in OMISII. 
Daytime and nighttime scannings were carried out in each 
research area, and the ground resolution was 3.6m. 
Simultaneous field measurements of ground spectrum, thermal 
infrared temperature, and soil moisture were also done in the 
scanning area with the flight. Thermal Infrared meter, soil 
moisture meter and Field Spectral meter provided the 
parameters for calibrations of image and relevant quantitative 
analyses. 
1.3 Image Processing and Results 
General image processing methods, such as color composition, 
grey stretching & transforming, are still powerful some times in 
extracting information, but for hyperspectral images with much 
more bands, the following methods are used to utilize all bands 
sufficiently to find information of cultural relics. 
3) Matched Filter 
Based on user-defined endmembers, each pixel is separated 
partly. Matched filter is used to calculate the percentage of 
user-defined endmembers of pixel by partial unmixing. The 
percentage distributed map of each endmember is determined 
by matching spectral curve of pixel in imagery and that of 
ground object in known spectral library. This method doesn’t 
need all endmembers in image. 
4) Spectral Feature Fitting—SFF 
Based on characteristics of spectrum absorption, non-classified 
ground object spectrum could be matched for classification with 
referenced spectrum by using the least squares method. 
5) Pseudo Colour Composition and Enhancement