The Establishment of Geospatial Data Framework
The GPS-supported fully digital photogrammetric system can promptly produce DOM, DEM and DLG. These digital products with the unit of mapsheet need to integrate a complete spatial database under the GIS environment. However, it is not the previous topographic map with primary graphic elements. Therefore President Clinton of the USA proposed National Spatial Data Infrastructure (NSDI) in 1994 and then the integration of a variety of generic data is called GSDF.

According to the national needs and very fast updating, GSDF should include DOM, DEM and several layers of DLG data. Within DLG vector graphic data, at least the following are required:

• Geodetic control network
• Boundaries of administration regions
• Transportation network
• Waterbody
• Geographical names and relative lettering and other necessary information acquired from DOM by operators or users.

GeoStar series of softwares in Windows NT can efficiently manage the raster-vector unity GSDF which was described above. This is because the softwares posses the following functions.

• Conduct check, roam and query within the entire spatial database
• Be capable of cover vector graphic data onto image data and update (modify, add and delete, etc.) graphic data using image data
• Is able to realize self-adaptive and multi-resolution display based on image pyramid, ie. image data can be automatically read from the corresponding layer according to the selected display scale
• Achieve image and DEM’s fundamental functions such as 2.5D display, query and roam, etc.
• Can convert all spatial data to other information systems supported by GIS hardwares and softwares in terms of user’s requirements
• Output visualization products with mapsheet or the given range, in terms of user’s needs

This software is capable to not only receive and process data from digital photogrammetric systems and remote sensing image processing systems, but also receive results from GPS receivers, total theodolites, map scanners or digitizing tables. Also, through API platform and ODBC, it can communicate with the well known database systems, such as Oracle, SQL Server, SyBase, etc. Furthermore, it can fulfill data exchange including input and output with the presently popular GIS softwares via the national authenticated exchange format for spatial data.

Experiments and Applications
WTUSM has produced the production line from imagery to GSDF by applying the above self-developed softwares. Through the mandatory testing and checking, the integration system of FDP, GPS and GIS has been widely applied in many production departments in China.

Up to date, the software of GPS-supported aero- triangulation has been installed more than ten big production departments and teams in China, while more than one hundred copies of VirtuoZo NT has been worldwidely sold. The users of GeoStar are over three hundreds, among which GeoTin producing DEM ever sold sixty copies within one month; map scanner software GeoScan sold over five hundreds of copies. The whole integration system has been equipped in the department of land of Guangdong province and used for provincial spatial data infrastructure.

Shown in Figure 2 is the interface of the WuCAP_GPS NT version which is the GPS-supported aerotriangulation software. Its empirical outcomes are indicated in Table 1. The results with the automatic measurement of image coordinates have better accuracy than manual measurement. The digital photogrammetric system VirzuoZo NT version is displayed in Figure 3, while its produced DOM and 3D landscape (originally color map) integrated with DEM are shown in Figure 4. Figure 5 shows the interface of GeoStar NT version, whose product ‘raster-vector unity spatial database’ (originally, the overlay of color graph and image) is partially displayed in Figure 6. This database will have 1000 GB data after completion and will be of great value for applications.


Fig. 2 GPS-supported aerotriangulation software WuCAPS_GPS

Tab.1 Results for GPS-supported aerotriangulation

Ground control points	Mensuration of image points	s0(mm)	Theoretical accuracy (m)			Number of check points	Practical accuracy (m)
			X	Y	Z		X	Y	Z
without GCP	manually	14.8	0.332	0.448	0.491	6	0.239	0.313	0.351
	automatically	12.5	2.728	2.126	1.082		2.383	1.825	1.077
with 4 corner points	manually	14.3	0.174	0.217	0.343	2	0.122	0.491	0.268
	automatically	12.2	0.127	0.147	0.253		0.350	0.331	0.196

Remarks: 1.The automatic mensuration of image points is accomplished by VirtuoZo NT. The scanning resolution of digitizing the aerial negative is 25mm.

2.S₀ is the root square mean error of the measurement of image points. Theoretical accuracy is the root square mean error of unknowns obtained by the formula is the variance-covariance matrix of unknowns;

Practical accuracy is the root square mean error for the coordinates of photogrammetric points calculated by the formula are the coordinate residuals of the ground check points.



Fig.3 Digital photogrammetric workstation VirtuoZo NT



Fig.4 3D landscape generating by VirtuoZo NT (originally color map)



Fig.5 Object oriented GIS software GeoStar



Fig. 6 Raster-vector unity GSDF managing by GeoStar (originally color map)