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A method for detecting a building shadow based on a ghost image

An image detection and building technology, applied in the field of aerial photogrammetry, can solve the problems that roof shadows cannot be detected correctly and the overall recognition is not high

Active Publication Date: 2019-04-16
GUILIN UNIVERSITY OF TECHNOLOGY
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Problems solved by technology

[0005] The present invention proposes a method for detecting building shadows based on ghost images to solve the problem that the overall recognition degree is not high and roof shadows cannot be detected correctly in previous shadow detection methods

Method used

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  • A method for detecting a building shadow based on a ghost image
  • A method for detecting a building shadow based on a ghost image
  • A method for detecting a building shadow based on a ghost image

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Embodiment example

[0023] In this embodiment, we select an aerial image of a foreign region for occlusion detection processing. The aerial image is taken by RC30 aerial camera, and the adjacent images covering the central city are dv1119 and dv1120, which have a heading overlap of 65%. The buildings in the image are complex and diverse, causing a lot of occlusion.

[0024] In specific implementation, the technical scheme of the present invention can be carried out by means of automatic operation of computer programming.

[0025] The specific operation steps of the ghost image shadow detection program provided by the present invention can refer to the flow chart Figure 4 :

[0026] Step 1, load the image file.

[0027] Convert original and ghost image files to grayscale images for processing. Load a digital surface model (DBM) file.

[0028] In this embodiment, the ghost image of the image dv1119 has been generated by the traditional orthorectification method. The loaded ghost image is ort...

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Abstract

The invention discloses a method for detecting a building shadow based on a ghost image. The method comprises the following steps: 1, secondarily utilizing a traditional orthographic correction result(the ghost image); 2, analyzing, finding and correcting a shadow inflection point with a relatively small error through photogrammetry knowledge; And 3, calculating a solar elevation angle and a solar azimuth angle in the DBM by using the coordinate of the shadow inflection point with a relatively small error to detect shadows on a ghost roof (roof obtained by orthographic correction) and the ground in the ghost image, and finally displaying a complete shadow detection result through layer superposition. When the method is used for detecting the building shadow, the problem that the shadow area boundary projected on the roof cannot be detected in the conventional method can be effectively avoided, so that the detection rate on the roof is increased by 33.33%. The shadow detection method is simple to operate, the shadow detection speed is increased, and the detection cost is saved.

Description

technical field [0001] The invention belongs to the field of aerial photogrammetry, and relates to a method for detecting building shadows based on ghost images, in particular to the accurate determination of the sun elevation angle, sun azimuth angle and the shadow area of ​​the building roof, so that the ghost image can reach The effect of real orthophotos. Background technique [0002] The image obtained after traditional orthorectification processing does not fully take into account the geographical information of the building shadow, which makes the spatial object in the shadow area deviate from its original position, and makes the building shadow greatly affect the accuracy of the orthophoto and availability. Therefore, in order to improve the quality of corrected images, shadow detection becomes a necessary link in the process of orthophoto correction. [0003] Previous model-based shadow detection methods mainly establish shadow statistical models based on the prop...

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Application Information

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IPC IPC(8): G06T7/507G06T7/70G06T17/05
CPCG06T17/05G06T7/507G06T7/70
Inventor 周国清沙洪俊
Owner GUILIN UNIVERSITY OF TECHNOLOGY
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