عنوان مقاله [English]
Lots of parameters like growing of plants, trees falling across power line, land sliding and flood may lead to massive damage of power line corridors. Therefore, several methods have been used for monitoring and inspecting power lines including field surveying, aerial image analysis and LIDAR analysis which are very time consuming and expensive. Implimantation of satellite images and remote sensing technology may be an alternative method. But this new method too, may have some limitations in analyzing small features. In this paper, the main objective is to discuss satellite images capabilities in automatic pylon extraction and finding power lines. For this purpose, IRS-P5 satellite images have been used as the main data. This sensor provides panchromatic images with spatial resolution of 2.5 meter. In contrast with some high spatial resolution sensors like WorldviewII and GeoEyeI that provides multispectral images with better spatial and spectral resolution (about 1.6m in multispectral bands and 0.5m in panchromatic band), it is more troublesome to extract pylons in P5 images. Indeed, these sensors can show a pylon and its shadow like two separate triangles, but in P5 images pylons are like dark speckels. Therefore, in this paper several conditions have been used to distinguish pylons and power lines correctly. Results show that the proposed method can satisfactorily extract pylons in homogeneous areas, but in rough regins that have lots of small dark speckles (like vegetation areas), the accuracy decreases. As the second objective of this paper, the capability of satellite images in measuring pylons’ height has been discussed. P5 stereo images can not find the height of the pylons, but sensors with higher spatial resolution, like Worldview I, have this capability. Although, even in this sensors, reaching stereo images matching pylons’ pixel may be a challenging task.
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