International Archives of the Photogrammetry, Remote Sensing and Spatial Information Sciences, Vol XXXV, Part B7. Istanbul 2004 
  
2. STUDY AREA AND MATERIALS 
2.1 Study Area 
Taipei City is located in the northern tip of Taiwan, and the city 
is divided into 12 districts. There are 19 areas of forestland 
designated as protection forests scattered in seven districts. 
Most of these areas were designated to protect water and scenic 
spots, and two of them were for protecting soils. Some 
protection forests are actually part of the Yangmingshan 
National Park, a very popular recreation area in the vicinity of 
the Taipei City. The elevation of the park ranges from 200 to 
1,120 meters with a total area of 11,455 hectares. Established in 
1985, the park features unique volcanic landscape and abundant 
fauna and flora species. Growing in water and land 
environments, there are more than 1,200 plant species, of which 
several are endemic species (Yangmingshan National Park, 
2004). The locations of these protection forests are shown in 
Figure 1. 
  
Figure 1. Study area 
2.2 Data 
2.2.1 Maps: Three types of maps including forest maps, 
cadastral maps, and topographic maps were used in this study. 
The forest maps were hand-drawing maps prepared by the 
management authority when the protection forests were first 
established. These forest maps were drawn in three different 
scales, i.e., 1/1200, 1/3000, and 1/6000. Because these maps 
were prepared nearly one hundred years ago, the conditions of 
the maps were not very good. In addition, these maps used a 
coordinate system that was not compatible with the other data 
and maps, therefore lots of efforts were spent to digitize these 
maps into digital format with current coordinate system. 
Cadastral maps were resulted from digital surveying. These 
cadastral maps were completed in 2003, and the map scale was 
1/500. Two forms of topographic maps were used in the study. 
Hard-copy topographic maps were done in 1980, and digital 
topographic maps were completed in 2002, both with a scale of 
1/1000. 
342 
2.2.2  Imageries: Digital image data used in this study 
included scanned photo base maps, aerial photographs, and 
orthoimages, with scale of 1/5000, 1/18000, and 1/5000. 
respectively. These imageries were used for field investigation 
planning, and land-use verification. Imageries of the study area 
taken on different years also provided valuable information for 
understanding the landscape and land-use changes within the 
protection forests. 
In addition, a DEM (digital elevation model) of the study area 
was acquired for profiling, slope, stream network, and 
watershed analysis. The objective was to evaluate if the extent 
of protection forests need to be altered in order to effectively 
protect the watershed areas. Elevation of the study area ranges 
from 200 to 1200 meters, and Figure 2 shows a part of the study 
area. 
  
  
Figure 2. Shaded relief of the study area produced from DEM 
2.2.3 Coordinates data: In order to provide high precision 
fundamental control measurements for a variety of different 
applications, the Ministry of Interior of Taiwan had setup a 
Satellite Survey Center to measure and provide data of 
coordinates of satellite oriented control points. A control points 
network consisting of satellite tracking stations and satellite 
oriented control points was built by the center, and the 
computed coordinates data were distributed to the general 
public. In addition to the satellite oriented control points data, 
some data of control points measured in cadastral surveying 
were also used in this study. 
2.2.4 Parcel records: Original parcel records dated back 
when the protection forests were established were not very 
useful because the administrative boundary and cadastre records 
had changed several times in the past few decades. This study 
collected as much cadastral information as needed and 
associated maps in order to ensure accuracy of the data. 
2.3 Materials 
2.3.1 Surveying instruments: GPS RTK receivers and total 
stations, both manufactured by Leica Geosystems, were used to 
measure control points and to locate the center of sample plots 
selected within the protection forests. 
  
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