State Bureau of Surveying and Mapping

About: State Bureau of Surveying and Mapping is a based out in . It is known for research contribution in the topics: Terrain & Pixel. The organization has 277 authors who have published 206 publications receiving 2044 citations.

Geoid Determination on China Sea and its Merge with the Geoid in China Mainland

Abstract: Geoid determination on China Sea via corresponding deflection of the verticals is obtained from satellite altimeter data with the inverse Molodensky formula. In order to examine the accuracy of the geoid, two measures have been applied. Firstly the gravity anomalies are computed by using the same data set of the deflection of the verticals with the inverse Vening Meinesz formula. Then the above gravity anomalies are compared with the actually measured gravity data on the sea for external examination. Secondly, the geoid on the China Sea is also computed by the above gravity anomalies with Stoke formula. The comparison of the two geoids is for internal examination. The mean square error for the external and internal examination is ±9 mGal and ±0.025 mGal, respectively. Geoid on the land is determined by gravity and GPS leveling data, and geoid on the sea is determined mainly by altimeter data. If the two geoids are to be merged together, then the difference, mainly systematic error, between the two kinds of geoid can be usually found. This phenomenon and its main causes are discussed and the so–called extended merge technique is suggested in the paper, especially this technique is suited to those coastal and shallow sea areas with sparse gravity data. The results of the computation with this technique demonstrate that the systematic error has been well reduced in the merge between the geoids of China mainland and China Sea.

Design and experiments of X-type artificial control targets for a UAV-LiDAR system

Abstract: Unmanned Aerial Vehicle-Light Detecting and Ranging (UAV-LiDAR) systems can potentially generate high precision Digital Terrain Models (DTM), especially for railway surveys. However, tradit...

Rural residential building extraction from laser scanning data and aerophotograph based on quadtree segmentation

Abstract: A new method is presented for the extraction buildings in rural area from light detection and ranging (LIDAR) normalized digital surface model (nDSM) on the basis of quadtree segmentation principles. Compared with aerophotograph, LIDAR generally provides more accurate height information but less accurate boundary lines. In our method the two data sources are integrated for building boundary extraction. First, nDSMs are segmented to image objects by a quadtree Algorithm. Building candidates are obtained based on a certain height threshold of segmented objects of nDSMs. The brightness index derived from the aerophotograph is used to remove shadows. Then the spectral information is used to refine the edge of the building, which is implemented by classifying spectrally similar neighbors to the class of building in high steep area. The greenness index is extracted to eliminate the influence of vegetation. The trees over building can be reclassified by finding the image objects that are completely enclosed by other image objects belonging to building. At last, after two types of morphological operations and area threshold are applied to the building objects to eliminate the spurious objects and to smooth object boundaries, a set of reliable and clean building objects are obtained.

Generalised total least squares solution based on pseudo-observation method

Abstract: In the generalised total least squares (GTLS) problem, observations can be perturbed by random errors that are dependently, inconsistently and normally distributed with a non-zero mean, and the coefficient matrix can hold any structure. In this contribution, a set of formulae for GTLS adjustment is derived using a pseudo-observation method. Based on the derived results, an iterative algorithm (algorithm 1) only for the estimation of parameters and a two-loop iterative algorithm (algorithm 2) for the estimation of parameters and variance factors are developed. Moreover, the derivative of a vector is introduced to deal with the structured TLS problem. A straight line fitting and a simulated 2D affine transformation experiment are performed to verify the applicability of the developed algorithms. The results show that algorithm1 can be used to simultaneously handle the structured coefficient matrix, correlated error and non-zero expectation problem, while algorithm 2 can be utilised to manage the variance co...

Ice-sheet surface elevation change from crossover of ENVISAT data

Abstract: Understanding the current state of the polar ice sheets is critical for determining their contribution to sea-level rise and predicting their response to climate change. Surface elevation time series especially can be used to study ice-sheet dynamics and the mass or volume balance of the ice sheets, which are relevant to global climate change and sea-level rise. During the last two decades, satellite radar altimetry or airborne laser altimetry could obtain accuracy by an order of magnitude greater than the traditional airborne barometric altimetry, which has a precision of typically several tens of meters at best and only a limited coverage. The widest coverage comes from satellites, especially from the ERS1/2 and ENVISAT, which extends to 81.5° of latitude, covering almost all of Greenland and most of Antarctica. In this paper, an algorithm for time series analysis based on crossover was used to obtain 4-year (September 2002–March 2007) ice-sheet elevation changes from ENVISAT data. The height of the who...