Soil Volume Computation Technique at Slope Failure Using Photogrammetric Information

영상정보를 활용한 사면 붕괴 토사량 산정 기법

Abstract

The uses of unmanned aerial vehicles (UAV) have been expanding in agriculture surveys, obtaining real time updates of dangerous facilities where human access is difficult, disaster monitoring, and 3D modeling. In reality, there is an upsurge in the application of UAVs in fields like, construction, infrastructure, imaging, surveying, surveillance and transportation. Especially, when the slope failure such as landslide occurs, the uses of UAVs are increasing. Since, the UAVs can fly in three dimensions, they are able to obtain spatial data in places where human access is nearly impossible. Despite of these advantages, however, the uses of UAVs are still limited during slope failure. In order to overcome these limitations, this study computes the soil volume change during slope failure through the computation technique using photogrammetric information obtained from UAV system. Through this study, it was found that photogrammetric information from UAV can be used to acquire information on amount of earthworks required for repair works when slope collapse occurs in mountainous areas, where human access in difficult.

최근 무인항공시스템의 활용으로 농작물 작황조사, 접근위험지역의 시설물 현황조사, 재해재난 모니터링 및 3차원 모델링 등 그 활용 분야가 확대되고 있는 실정이며, 건설, 인프라, 영상, 측량, 농업, 감시, 수송 등 실제로 여러 분야로 활용사례가 계속 늘어나고 있다. 특히, 산사태와 같은 사면 붕괴 발생 시 무인항공시스템 적용에 대한 시도가 많아지고 있으며, 무인항공시스템은 3차원 비행이 가능하기 때문에 접근하기 어려운 공간 정보를 확인할 수 있다. 하지만, 이러한 장점에도 불구하고 사면 붕괴 발생시 무인항공시스템 활용은 아직도 제한적인 실정이다. 본 연구에서는 이러한 한계성 극복을 위하여 사면 붕괴로 인한 토사량을 무인항공시스템의 영상정보로 산정하는 기법을 고찰하였다. 본 연구를 통해 산악지역 등 접근이 어려운 지역에서 사면 붕괴 발생시 복구공사에 필요한 토사량의 정보를 취득하는데 무인항공시스템 영상정보를 활용할 수 있을 것으로 판단된다.

Fig. 1. eBee (UAV) drone

Fig. 2. Sony WX RGB camera

Fig. 3. Data obtaining and processing flow chart

Fig. 4. Survey site location (daum maps, 2018)

Fig. 5. Setting survey mission area in eMotion2 S/W

Fig. 6. UAV drone survey mission details

Fig. 7. GCP points selected in survey site

Fig. 8. GPS survey of GCP points

Fig. 9. eBee UAV drone take-off

Fig. 10. Volume analysis by Pix4Dmapper

Fig. 11. Volume analysis by virtual surveyor

Fig. 12. Flight data manager in eMotion software

Fig. 13. UAV photos and flight log file selection in eMotion software

Fig. 14. Output coordinate system selection

Fig. 15. Processing options input

Fig. 16. Applying correct coordinates from GPS survey to GCP1 point in Pix4D

Fig. 17. Orthographic image of site before failure

Fig. 18. Orthographic image of site after slope failure

Fig. 19. DSM of site before slope failure

Fig. 20. DSM of site after slope failure

Fig. 21. Soil volume calculation before slope failure by Pix4Dmapper software

Fig. 22. Soil volume calculation before slope failure by virtual surveyor software

Fig. 23. Soil volume calculation after slope failure by Pix4Dmapper software

Fig. 24. Soil volume calculation after slope failure by virtual surveyor software

Fig. 25. 3D scanning

Fig. 26. Using 3D scanner before slope failure

Fig. 27. Using 3D scanner after slope failure

Table 1. Ground control point survey result from GPS

Table 2. Slope volume change calculation before and after failure and comparison of result from two softwares

Table 3. Specifications of 3D scanner