Abstract: [Purposes] To solve the problems of insufficient accuracy and low efficiency in real-scene 3D modeling of complex terrain at water control projects,and to promote the in-depth application of oblique photogrammetry in smart water conservancy construction.[Methods] Taking the Wanjiazhai Water Control Project on the Yellow River as the research object,DJI M300 UAV is used for full-area oblique photography and P1 camera for close-range supplementary photography in key areas to obtain multi-view images with 2 cm ground resolution.Based on DP Modeler software,a refined workflow of “full-area inspection-classification and refinement-monolithic modeling-model fusion” is established to eliminate model defects and construct a surveying and mapping-grade real-scene 3D model.[Findings] The modeling results show that the model has realistic texture and complete geometry,and can accurately capture structural deformation of hydraulic structures.Both horizontal and vertical accuracy meet the requirements of water conservancy engineering surveying and mapping.The operation time is shortened by 60% and modeling cost reduced by more than 30%.[Conclusions] The study indicates that UAV oblique photogrammetry for 3D modeling can effectively solve the problem of high-precision modeling of water control projects in complex canyon terrain,providing technical support and practical reference for digital supervision of water conservancy projects,intelligent construction of hydropower stations,and intelligent upgrading of water conservancy infrastructure.

Key words: UAV aerial survey, oblique photogrammetry, water control hub, model refinement, survey-grade precision