JPH0257649B2 - - Google Patents

Description

[Detailed description of the invention]

The present invention relates to a solid image monitoring method that can be applied to observing the current status of power transmission line routes and the like in a short period of time. Each electric power company has constructed considerably long power transmission line routes across mountainous areas for the purpose of power transmission. Many of these power transmission line routes have been constructed for many years, and the situation in the mountains along the route is likely to have changed considerably from when they were constructed. For example, trees that were relatively shrubs at the time of construction may have grown over the years to the point where they are touching the power lines. Such a condition is likely to cause failures such as disconnection of the power transmission line, so it must be investigated in advance. Furthermore, due to recent developments in residential land, what was once a mountainous area when the power transmission line was constructed may now be turned into residential land, with private houses located directly beneath the power transmission line. Situations like this can lead to disasters if not fully understood, so it is important to investigate them in advance. However, such preliminary surveys are difficult to conduct because the power transmission line routes generally span mountainous areas and are very long distances, so it is extremely difficult for observers to actually search along the power transmission line routes. It is difficult and time consuming. If you observe the power transmission line route from the air using an aircraft such as a helicopter, you can cover the entire length of the power line route in a short time, but simply using an aircraft allows you to pass through each point at high speed. Because of this, it is easy to overlook things, and it is not possible to observe each location in detail. Another option is to record data using conventional aerial photogrammetry and then observe and analyze the aerial photographs precisely through a wide variety of technical procedures. This is not practical as it is time consuming and expensive. For this reason, there has been a demand for a method that can easily and accurately observe, analyze, and record the current situation at each point along a desired route, such as a power transmission line route, in a short period of time. In order to meet such demands, the present invention provides a solid image monitoring method that can be applied to observing the current status of power transmission line routes and the like. Next, the present invention will be described in detail with reference to embodiments of the present invention based on the accompanying drawings. In order to facilitate understanding of the present invention, the principle of stereoscopic vision will be explained before explaining the method of the present invention. Humans have two eyeballs, which allow them to perceive the distance of objects. This function is nothing more than detecting differences in visual angle within the eyeball. Let us now consider a set of 3D photographs of the same object taken from different positions. As shown in FIG. 1, there are photographs 2 and 3 taken of the object 1 at different positions 0 and 0'. The vertical point N and the camera lens placed at each position 0 and 0' are
The image corresponding to N' is shown on each photo 2 and 3 as follows:
Appearing as indicated by reference numbers N and N' respectively, the image of object 1 appears on each photograph 2 and 3 as indicated by reference numbers 1A and 1B. Put these two photos 2 and 3 into the second
When viewed with human eyes 4 and 5 as shown in the figure, images 1A and 1B on each photograph are perceived as a three-dimensional image (solid image) 1' similar to the object 1. In this case, the difference from when looking at the real thing is that the eyeballs are focused on the real thing, needless to say. However, when a three-dimensional image is perceived through a photograph, the eyeballs must be focused on the photograph.
Therefore, some training is required to perform stereoscopic viewing of an object from such two photographic images.
Furthermore, when the baseline length is long, such as in aerial photography, when trying to view it stereoscopically, there is a limit to the baseline length of the human eye (usually 6 to 6.5 cm), so the apparent difference in height becomes quite large. This is called hypersensitivity. Therefore, the relationship between the photographing altitude, the photographing base line length, and the height of the object for creating a stereoscopic photograph so as not to cause such a feeling of excessive height will be described in detail below. First, the geometric relationship between single photographs as shown in FIG. 3 will be explained. A photograph is taken vertically downward from a height H. At this time, the point on the ground directly below the camera is called the "vertical point", and this is shown in Photo 7.
Above, it is called the ``photographic vertical point.'' The image produced by an optical system using a lens is "centered photography", and the center of the lens is called the "projection center", and this point on photo 7 is called the "principal point".
That's what it means. As shown in FIG.
The positions of the images 8A and 8B are different on A and 9B. This positional difference p is called "parallax". The ratio between the imaging height H and the imaging baseline length B in FIG. 4 is referred to as the "baseline ratio", and the larger the baseline ratio is, the more the three-dimensional effect is perceived by the human eye. Regarding this baseline ratio, in photogrammetry, 0.05<B/H<0.3, and for stereoscopic observation only, 0.01<B/H<0.1 is considered appropriate. The human eye base line length is b, and the angular resolution of the eyeball is Δθ.
(radians), the distance L at which depth is perceived is given by L=b/Δθ. Here, the angular resolution of the human eye is about 0.05 to 0.15 radian. The measurement accuracy in the height direction of the 3D image is the measurement accuracy of the parallax difference in the height part,
given by the baseline ratio and the focal length of the camera. The vertical distance Z and parallax p between the camera and the object 8 shown in FIG. 4, the focal length f of the lens, and the base line length B
The relationship with is given by Z=f・B/p. Then, the height difference h of the object 8 is
Given the parallax difference Δp=θ′−θ ₀ , the parallax p ₀ of the lower part of the object 8, and the distance H to the lower part, h=H(Δp/p ₀ ) is given. If h is the height difference of the object at the distance between the camera and H, then the measurement accuracy h/H of h measured by stereoscopic photography is given by h/H=(H/B)・(Δp/f) . In other words, in order to obtain an accuracy of 1m height difference at a shooting altitude of 1000m, the parallax measurement accuracy on the photo must be 0.01mm.
If we use a camera with a focal length of 100mm,

[Table] Video tape records 30 images per second, so assuming the ground speed V of the helicopter is 100 km/hour, it takes 12.8 seconds to obtain a baseline length of 357 m.
It takes 6.4 seconds to obtain a baseline length of m, 3.2 seconds to obtain a baseline length of 89m, and 384 seconds for still images.
192 sheets, 96 sheets each. Therefore, the time difference in which the playback from the other videotape should be delayed with respect to the playback from the one videotape is 12.8 seconds, 6.4 seconds, or 3.2 seconds, depending on the measurement accuracy and shooting altitude. do it. If a supervisor views the continuous images thus displayed on two side-by-side cathode ray tube display devices using, for example, a stereoscope, based on the principle of stereoscopic vision described above, the viewer will be able to see the true image along the power line route. You can see an image similar to the real image seen from above. Therefore, for example, the current situation, such as the height relationship between trees and power transmission lines, can be accurately grasped. This stereoscope is well known; the image displayed on the left cathode ray tube display is visible only to the observer's left eye, and the image displayed on the right cathode ray tube display is visible only to the observer's right eye. It is meant to allow you to enter. In the embodiment of the present invention described above, two cathode ray tube display devices and a stereo mirror are used to allow the supervisor to see a solid image of the power transmission line route. It is also possible to see a solid image of the power transmission line route using a single cathode ray tube display device and polarized glasses. In this alternative embodiment, successive images from the aforementioned original videotape and from the duplicate videotape are simultaneously displayed on the same display surface of a single cathode ray tube display, offset from each other by a time difference producing the aforementioned parallax. If it is reproduced and displayed, and an observer observes it while wearing polarized glasses, based on the principle of stereoscopic vision mentioned above, one can see an image similar to the stereoscopic image seen from directly above along the power transmission line route. Can be done. These polarized glasses are well known, and the left eye of the person wearing them will be able to see images being displayed on the display screen of the cathode ray tube display, such as those reproduced from the aforementioned original videotape. Only images are shown to the right eye, and among the images displayed on the display surface of the cathode ray tube display device, for example, only the images being played back from the above-mentioned copied videotape are seen. According to this embodiment, if a plurality of observers wear polarized glasses, they can simultaneously observe a solid image of the power transmission line route. In the two embodiments described above, the physical image of the power transmission line route is continuously monitored along the route, but the physical image of one specific point on the power transmission line route is observed in detail. An embodiment of the stereoscopic image monitoring method of the present invention suitable for the following will be described below.
The videotape vertically photographed along the power transmission line route with a video camera mounted on a helicopter as described above is reproduced and displayed on the display surface of a display device such as a cathode ray tube using an appropriate reproduction device. Then, when you come to an image of the desired point on the power transmission line route that you want to observe and analyze in particular detail, you take a still photo of the displayed image with a Polaroid camera, 35mm film camera, etc. to create a single still photo. Next, after an interval of time that causes the parallax as described above from the display of the image obtained by taking the still photograph, the image to be reproduced and displayed on the display screen of the display device is taken again as a still photograph in the same manner.
Create another still photo. If the two still photographs created in this way are juxtaposed and observed using a stereoscope, a supervisor can see the desired point on the power transmission line route from directly above, based on the principle of stereoscopic vision described above. You can see an image similar to a static solid image. In this case, since it is a stationary solid image, the observer can take sufficient time to analyze and consider the situation at the target point from the solid image. Furthermore, if the two still photographs thus created are analyzed using an analytical plotting machine, the situation at the desired point can be plotted very easily. Although the above-described embodiment of the present invention has been described with reference to the case where it is applied to the observation of power transmission line routes, the solid image monitoring method of the present invention is not limited to such observation of power transmission line routes, but can also be applied to other geographical features. It can also be applied to observing the status of telephone line networks, etc., in a short period of time. Furthermore, in the above-mentioned embodiment, vertical shooting was performed using a video camera, because shooting onto a videotape requires no processing such as development, can be played back immediately, and can be easily copied. If it is acceptable to take some time for processing, the stereoscopic image can be similarly monitored by vertical photography using an 8mm film camera or a 35mm film camera, and the present invention This also includes cases. According to the solid image monitoring method of the present invention as described above, the basic original image is recorded at a ground speed of 100 km/h.
If carried out using a helicopter around the same time, it would be possible to cover approximately 200 km of power transmission line routes in one operation time (approximately 2 hours), making it possible to easily conduct observations over a wide area in an extremely short period of time. In addition, videotape is 3/4 of the high-precision image for professional use.
Assuming that an inch-wide tape is used, it is possible to record approximately 20 minutes on one cassette tape, and a route with a constant length of approximately 30 km can be recorded on one cassette tape. The cassette tape has an external size of 40 x 150 x 210 mm and is also heavy.
It is lightweight and compact at 560g, and does not require a special storage environment or filing stocker, making data filing very easy. Furthermore, by filing the data, it is very effective in that the actual image of a particular route can be reproduced, observed, and analyzed as many times as necessary. In addition, in the stereoscopic image monitoring method according to the present invention, it is preferable that the ground speed and ground altitude of the helicopter that performs vertical photography are always kept constant.
It is practically difficult to keep these constant. However, even if these ground speeds and ground altitudes change slightly during continuous vertical shooting, the changes can be analyzed and corrected by applying the recorded images to an analysis plotter, for example. Because you can
Accurate physical image monitoring can be performed.

[Brief explanation of the drawing]

Figures 1 and 2 are schematic diagrams explaining the principle of stereoscopic vision used in the present invention, and Figures 3 and 4 show the photographing altitude, photographing baseline length, and object height for creating a stereoscopic photograph. FIG. 5 is a schematic diagram for explaining the relationship between the two, and FIG. 5 is a diagram schematically showing vertical photographing by a helicopter along a power transmission line route in the stereoscopic image monitoring method of the present invention. 10...helicopter, 11...power line route, H...height above ground, V...speed above ground.

Claims (1)

[Claims] 1. Continuous images along a desired route such as a power transmission line route are created at a substantially constant speed by vertical photography from a substantially constant height, and the continuous images are used as original images. a duplicate image is created, both images are displayed simultaneously and consecutively with a time difference that creates a parallax, the display from one of the images is visible only to one eye of the observer; A method for monitoring a solid image, characterized in that the display from the other of the images is directed only to the other eye of the observer. 2 Create a series of images along a desired route, such as a power transmission line route, at a substantially constant speed by vertically shooting from a substantially constant height, continuously reproduce the continuous images, and reproduce the reproduced image. From the above, two still images of the target point to be monitored on the route are separated by a time interval that causes parallax, and a substantial image of the target point is deciphered from both of the still images. A real image monitoring method characterized by: