1. Tilt photogrammetry principle
Tilt photography is the international Remote sensing field of surveying and mapping emerging developed a high and new technology, combined with traditional Aerial photography and close range measurement technology, to subvert the previous orthogonal projection as can only be taken from the Angle of vertical limit, by carrying on the same flight platform more sensors, at the same time from the vertical, front, left, right and rear view images collected a total of five different angles, as shown.
Among them, the vertical photographic image can be processed by traditional Aerial photogrammetry technology to produce 4D (DEM, DOM, DLG and DRG) products; Front view, left view, right view and view 4 oblique photographic images, with an Angle between 15° and 45°, can be used to obtain rich texture information on the side of the feature.
Through efficient and automated three-dimensional modeling technology, to quickly build feature location accuracy of true 3 d scene, intuitive grasp of the target area topography and the details of all buildings, could be used to power and water conservancy project construction, geological disaster emergency command, etc. Meanwhile, detailed and accurate, vivid space basic geographic information data support and public service.
2. Technical flow of real 3d modeling
At present, the post-processing software of 3d modeling using tilt photography technology makes use of vertical and tilt images of ground objects and a few ground control points to build a high-resolution true 3d model based on real image texture.
The 3d model data produced can be imported into the GIS platform for application analysis. For example, coordinates, distance measurement and area statistics of buildings in crowded areas of transmission lines can be carried out, and plans of crowded areas can be drawn. Accurately measure the height of the crosswise tower and optimize the crosswise design.
3. Application of tilt photography technology in rapid survey of transmission line corridor resources
Using oblique photography technology to quickly build target area for 3 d scene, investigating the fast transmission line corridors, channel resources, reasonable avoid the town planning, large-scale industrial and mining enterprises, nature reserves, forest dense coverage, and mountains and heavy ice difficult terrain and bad geological area, make the circuit design of safe and reliable, economic and reasonable, reduce line engineering construction's impact on local economic development.
(1) Accurately measure the demolition area of buildings in the corridor
The 3d model of real scene produced by oblique photogrammetry has the characteristics of good aging, high accuracy and abundant information, and can accurately measure the coordinates, width, height and area of the ground object. On the basis of the true three-dimensional model, the detailed interpretation and indoor measurement are carried out to quickly calculate the number of building floors and actual area in the crowded section of the transmission line, so as to effectively estimate the amount of house demolition necessary for the construction of the line project, so as to make the construction compensation cost accurate and reasonable, and reduce the civil difficulty of construction.
(2) Accurate determination of forest vegetation attributes and coverage
For the densely covered area in the corridor of the transmission line, the tree species and distribution range can be intuitively determined from the true three-dimensional model, and the height of the ground trees can be measured accurately. By optimizing the design of the route path, we can effectively avoid the densely wooded area, reduce the length of the route in the wooded area, especially in the fast-growing eucalyptus forest area, reduce the height of the designed iron tower and the amount of tree cutting, effectively control the compensation cost of green seedlings, and protect the ecological environment.
(3) Quickly survey treacherous terrain and harsh geology
By realistic 3 d environment, designers can quickly intuitive grasp of transmission line corridors within the channel details of landform features, on the premise of economic and reasonable, route choice as far as possible avoid collapse, landslide, mountains, ice, water, and mining goaf difficult terrain and bad geological area, to ensure that every base DaWei won't appear can't stand tower caused by topography and geologic factors of problem, is advantageous to the line coordination and subsequent construction, make a new line more safe and reliable.
(4) Quick measurement of cross height
For the important crossings along the railway, expressway, transmission lines and other lines, the coordinate, distance and height information of the objects to be crossed can be measured accurately on the true three-dimensional model, and the crossing position of the line path can be reasonably optimized, which is conducive to the construction of spanning tower and laying out, and the cost of engineering investment can be effectively controlled. At the same time, the contradiction between the lines to be built and the cross-crossing facilities along the line should be coordinated comprehensively, so as to reduce the cross-crossing of the transmission lines already built, especially the transmission lines with high voltage level, reduce the power outage loss during the construction process, and realize the harmonious development of power construction and economic construction.
In conclusion, it is innovative and advanced to apply tilt photography technology to the rapid investigation of transmission line corridor resources. Good by aging, high precision of 3 d model of real optimization design for transmission lines, especially in crowded areas buildings, trees dense coverage area, bad geology area and cross crossing facilities complex areas, which can effectively improve the quality of design of transmission lines and depth, reduce the sinuosity of line, make the circuit path to achieve the best design parameters, optimization of engineering construction investment cost.
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