The International Archives of the Photogrammetry, Remote Sensing and Spatial Information Sciences. Vol. XXXVII. Part B4. Beijing 2008 
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Figure 3. Diagram of task planning by image block bounds 
There is an extra automatic process for digital aerial photo in 
seamless mapping. Generally speaking, a stereo model which is 
made up with adjoining photos between them forward lap is 
about 60% is appropriate for stereoscopic measuring. However, 
the forward lap between aerial digital images is usually about 
the 80%. A stereo model which is made up with adjoining 
digital aerial photos is not appropriate. Because digital aerial 
cameras are extensively used for photogrammetry and digital 
aerial photo is becoming an important data source for digital 
photogrammetric process. In order to stereoscopic measuring 
from the data source, a technique to find most appropriate 
stereo models from the photos in a block is developed and 
implemented in seamless mapping system. Through the 
technique stereo models are automatically created for a task. 
These models are stored at the server end and are prepared to be 
downloaded to workstations. 
Finished the task planning, task data are created automatically 
by server from raw data of project. The new invented data sets 
form work units in seamless mapping system. At the client end 
these work units are processed by different operators. The 
whole project is divided and ruled like so. 
Because of being deposited on the server, task data should be 
accessed by operators by a certain means. In the seamless 
mapping system, task data is accessed through authentication. 
That is, operators on the clients must successfully log on the 
server with their user identities and passwords and then 
download data from the server to their workstations. In order to 
access data by operators it is necessary that tasks must be 
dispensed to operators and set corresponding roles for different 
operator. The dispensing work is done on the server by 
administrators. When all tasks are dispensed, operators are able 
to access their dispensed tasks at the client end. 
Mapping is a long term procedure. During the procedure all 
dispensed tasks processed at the workstations should be 
monitored by administrators to estimate the progress of whole 
mapping project. Task monitoring at server end is a very useful 
function for administrators to do this kind of estimation. With 
the help of task monitoring, it is convenient for administrators 
at their offices to monitor the progress of the individual task 
without going to produce departments. Through the monitoring 
function administrators know which operator is processing 
which task and how much the task have been done. The task 
monitoring is illustrated as the figure 4. 
Figure 4. Monitoring of cartographic mapping progresses 
Beside the above discussed functions, server also has a function 
to support concurrent access and transport task data. With the 
function task data is able to access by operators. 
2.2 Workstation 
Workstation is a common PC with stereoscopic observation 
equipments, where cartographic map is collected by an operator. 
As the above description, mapping is divided into two parts: 
automatic processing and human-computer interactive 
processing. Automatic processing is done at the server end, 
interactive process is done at the client end. Workstation is 
human-computer interactive process software at the client end. 
Function of a workstation is very simple. It just is used for 
operators to manual measurement in stereo image pairs just like 
as the traditional mapping system in DPW, but there are some 
differences between the workstation and DPW. 
Firstly, the way of dispensing task is more convenient. In the 
DPW environment, task dispensing is accomplished just by a 
manual means. Administrators tell operators do what tasks and 
where data related these tasks are obtained. Then operators 
manually copy data from computers where data is deposited to 
their computers according the administrator indications. This 
kind of dispensing task is cockamamie and low efficient. 
However, dispensing task is automatically processed and data 
deposits are transparent for operators in the seamless mapping 
system. When operators log on the server from their 
workstation, all tasks dispensed by administrators at the server 
end are listed in the form of GUI (Graphical User Interface) at 
the client end. For an operator, what to do is just to click the 
task items in the GUI and the data related the selected task will 
be transported to their workstation. The diagram of task 
acquirement is shown in the figure 5.