2004 Volume 44 Issue 6 Pages 331-340
In each country of Southeast Asia, there has been lots of slope hazard including a landslide and a slope collapse caused by the geological feature condition and climate condition, and rapid city development will increases the disaster in the future. However, the technology about city protection against disasters in these countries has been undeveloped technically.
Authors have been developing a monitoring method of slope behaviors by using digital photogrammetry. Photogrammetry is defined as a measuring technique constructing the modeling of a three-dimensional (3D) space using two-dimensional (2D) images. Photogrammetry has the advantage of measuring deformation of an object by some photos with excellent cost performance. This paper proposes that many engineers are able to carry out photogrammeric work without reliance on photogrammeric technicians and shows that photogrammetry has the advantage of measuring deformation of a slope by some photos with easy measurements. When measurements are performed without control points, the normal-equation matrix has a rank deficiency of 7 depending on the three translations, three rotations and the scale in the network of observations. In order to eliminate the rank deficiency of the normal-equation matrix we must find seven additional equations. We present the geometrical analysis for the problem to measure the three-dimensional coordinates of measurement points without control points. This paper also shows a numerical method for calculating sufficiently good initial approximate values. This performance is suitable for a monitoring tool used for a protection against slope hazard in Southeast Asia. This digital photogrammetric system can remove human skills in measurement tasks, so it is possible to use it immediately when necessary.
The applicability of digital photogrammetry is discussed with its accuracies in Taiwan. Recently there are a lot of constructed roads passing through the soft rock areas in Taiwan. The main formation of soft rock in this country includes sandstones, shale, and mudstone. Due to the poor engineering properties of soft rock, there are many slope hazards along the road. The digital photogrammetry demonstrates that our method has a high potential to prevent the slope hazards in Southern Asia.
