In order to solve the problem of the linear measurement of arch ring for the detection of bridge,a new method is presented that measures the arch ring using a reflectorless total station on the side of the arch bridge and the detail operations are given. Taking account of weakness of edge suveying using a reflectorless total station,some formulas on the 3d coordinates calculation of the above and down edge of the arch ring based on the arch ring points are deduced.According to the law of error propagation, the accuracy of the X and Z axial coordinates are analysed.It is helpful for calculating lateral and vertical deformation and biridges elevation map that the transformation from free-station coordianates to the birdge axis coordinate by programming using EXCEL software is achieved.The method is used for bridges arch ring axial measurement in Qingcheng town,Yuzhong county,Gansu province,and its deformation is consistent with the measured results of the dial indicator,which satisfies the requirement of bridge detecton accuracy.So it is showed that the method is a good way of linear measuring of bridges arch ring.

In order to solve the problem of construction of 3D virtual campus, based on 3D modeling function of SketchUp,KML language,Southern CASS and free data and platform provided by Google Earth,technological routes and detailed solving methods of constructing virtual school were researched.Taking the Yuzhong campus of Northwest University For Nationalities as an example, this paper focuses on the technical process and operation skills of building three-dimensional model, texture mapping,3D model publishing in Google Earth. It has been proved that this method has the advantage of flexibility in the construction of 3D virtual campus which has guiding significance. In conclusion, the technology road map based on KML and Google SketchUp technology for 3D virtual campus system is feasible and practical and shows advantages in the aspects of model optimization and lightweight architecture..