2004 Vol. 29, No. 9
From both job prospects and technological development trends of geospatial technology (geomatics), the author describes why earlier in 2004, the US Department of Labor identified geotechnology (i.e.geospatial technology)as one of the three most important emerging and evolving fields, along with nanotechnology and biotechnology.According to spatio-temporal data acquisition, processing, management and information services, the future developments of geomatics are briefly analyzed.
A new class of GNSS ambiguity estimator is introduced in this paper.This class is referred to as the class of integer equivariant(IE)estimators since it still obeys the important integer remove-restore principle of integer estimation.It is shown that the IE-class is larger than the class of integer estimators as well as larger than the class of linear unbiased estimators.We will also give a useful representation of IEestimators.This representation reveals the structure of IE-estimators and shows how they operate on the ambiguity float solution.Finally, the best integer equivariant estimation is proposed.
On the basis of the observations at GPS fiducial station of crustal movement monitoring network of China from 1999 to 2001, obtained by the result of global solutio and local solution, the changing tendency of GPS fiducial station coordinate and velocity field is anasolution, the changing tendency of GPS fiducial station coordinate and velocity field is analyzed.The statistical result of accuracy of GPS coordinate and velocity field is given.
Bernese GPS Software 4.2 is used to analyze GPS data from six repeated surveys occupied by the GPS network of the Three Gorges Reservoir Induced Earthquake Monitoring System from 1998 to 2003.The result shows that the crustal deformation in the Three Gorges Reservoir area is less active with a marginally measurable rate of 0 and 3mm/a(±0.1~±2.0mm/a)with respect to stable South China. Whereas, The vertical subsidence is about 10mm to 35mm alongshore after impoundment.We have simulated present-day GPS velocity solution with a bi-cubic spline interpolation function to estimate the horizontal strain rate fields before impoundment.The result shows that the tectonic deformation background of the Three Gorges area is slight (the horizontal strain rate is about 10-9/a to 10-10/a).
According to outlier detection theory this, paper proposes a new algorithm useing the positioning domain to detect the cycle slip in satellite-borne GPS carrier phase measurements, which is defined as varying residual in epoch-by-epoch carrier phase measurements(VAREC).The results indicate that the algorithm can detect all outliers provided by more than 5 GPS satellites tracked by the satellite-borne receiver simultaneously.
On the basis of the discussion of the present situation and development of application of the navigation satellite system in China, this paper compares and analyzes the superiority and inferior position in application of Beidou navigation satellite system.At the same time, the forecasting of market about the numbers of users and production value of the Beidou navigation satellite system is made and the economical and social benefits are analyzed.
The fictitious gravitational potential solution of a sphere coincides with the earth's real gravitational potential field outside the earth is a series, which was not proved and only previously postulated as a uniformly convergent series.In the paper, it is proved that the series solution mentioned above is indeed uniformly convergent.
There are two main aspects in 3D city reconstruction:3D geometric information collection and surface texture restoration.The new methods for reconstructing the 3D city with both the oblique and perpendicular photographic images are presented.The mathematical model for restoring IKONOS stereo images by rational polynomial coefficients (RPC)is analyzed and performed in VirtuoZo digital photogrammetric workstation.Using its rapid image matching technique, this paper realizes the generation of digital elevation model (DEM)and orthoimage and the ground feature collection either manually or semi-automatically.
Bi-directional reflectance characteristic is one of the most important factors of radiance distortion.This paper discusses the radiance distortion caused by ground bi-directional reflectance character and puts forward an improved bi-directional reflectance distribution function (BRDF)model based on kernel-driven model.The experiment of MODIS radiometric calibration shows that the improved approach is effective for MODIS radiance distortion.
A residential area texture description based on the 3 ×3 region grey deviations is designed, and the Gauss blur is applied to make the residential area in the texture feature image possessing accordant grey value and limited contrast relative to the background area so as to obtain self-adaptive threshold for image segmentation.And a skeleton processing is proposed to eliminate the road from the residential area.The experiment results show that this technique is very simple and effective to the semi-automatic extraction of the residential areas and can meet the precision requirement of the mapping and surveying with satellite images.
This paper presents a method for image quality descending analysis to the motion blur images using the Kalman motion model.The image restoration algorithm based on the Kalman motion model is designed for the motion blur images restoration processing.The detail restoration steps based on the Kalman model are designed, and the corresponding quality assessment methods are selected to evaluate the restoration quality.The restoration results of the blur freight car images in the freight car weighting system show that the blur images get high quality and the restoration algorithm is effective.
With the principle component analysis (PCA), this paper preserts a new approach to effectively incorporating texture and structure information into the classification procedure to detect urban building in Beijing by using Landsat7 ETM+ panchromatic image.The results indicates that the texture and structure information are effectively incorporated into the classification procedure with PCA and are helpful to detect urban building to achieve the accuracy of 81.33%.Besides, the results show that Landsat7 ETM+ panchromatic image can be regarded as a good alternative of spot panchromatic image in urban building detection with the identical ratio of the two results reaching 89.42%.
A new method for the geologic logging of digital photos of tunnels and its principle are introduced.This paper also discusses the basic algorithm of digital photo geologic logging for tunnels, i.e. digital image rectification, digital image mosaic, measurements of geologic elements of attitude of layers, and the generation of logging graphs.Practice proves that the project of geologic logging of digital photo based on a normal digital camera is quite effective.And the validity of the algorithm has been veritied.
In pyramidal algorithm, an image is decomposed into multiresolution subbands with sets of tree-structured coefficients.A novel coefficient partition algorithm is introduced to split coefficients into two sets using a spatial orientation tree data structure.By splitting the coefficients, the overall theoretical entropy is reduced due to the different probability distribution for the two coefficient sets.A lossless coder based on the algorithm has a better performance than other wavelet-based lossless coders in our experiments.
Through integrating WebGIS, GPS, GSM effectively, this paper develops an Internet-based vehicle monitoring information system.A three-tier system architecture of B/S mode and composed function modules are designed in detail.Then relative key technologies are described.Last, the validity, stability and extensibility is demonstrated through application instance.
This paper discribes the basic concept and principle of analytical operation of spatial data cube.In the process of analysis, the methods that show examples for these analysis functions are adopted in order to make reader more intelligible.
Because of notional or semantic fuzziness and imprecise measurements, many data in spatial databases are imprecise.In this case, linear objects are not crisp lines but some narrow zones that include true lines.And we must distinguish the topological relations between these linear objects.In this paper, the descriptive methods of uncertain linear objects in the present are summarized, and the 9-intersection model for describing topological relations between crisp linear objects is applied.Then the topological relations between uncertain linear objects are described and determined by a qualitative analyzing method.
Based on the research of three-tier network service model of WebGIS and the technology of multi-server, this paper proposes a new extend model that processing GIS customs web requirement applying multi-server technology.In the procedure of constructing this model, proposes some methods to balance the load among servers.Storing and indexing GIS spatial data in multi-scale in database, keeping client's AOI data area in client side to decrease the client's requirement and transforming the load dynamically among servers can make the server cluster provide web service stably and quickly for the GIS client.It is significance for the development of GIS to issue the geographic information data on the Internet.
On the basis of the concept of RGB subspace developed in this paper, we purpose that the whole RGB space should be divided into some RGB subspaces;thus in the subspaces the three dimensional one-order transferring function can be deduced by using LSM from the device RGB space to CIELAB space directly.This method can be used in color correcting for scanning input data.
This paper develops a model of wide-band multi-spectral space for color representation based on the PCA algorithm and defines "cumulative space covering ratio (CSCR)" to determine the efficiency for space representation and reconstruction.Eperimental results show that this kind of wide band multi-spectral space can represent original spectral spaces.