JP2005283476A - Illegal dumping place detection system - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To objectively and efficiently detect an illegal dumping place with high accuracy even in case that it is filled up or shielded by trees or the like. <P>SOLUTION: An airplane with a laser scanner surveying machine is flown over a monitoring area, topographic three-dimensional data are acquired to form a tomographic map, in addition to recording of information for the own position and inclination of the airplane, by emitting laser beam to the ground and measuring the returning time of the reflected echo, a topographic alteration part is extracted by detecting a secular minute change of topographic contour lines, and an illegal dumping place is detected based on it. At that time, the reflection intensity of the laser beam is determined to form a distribution map thereof, and a reflection intensity abnormality part is detected, whereby a metallic substance dumping place on the ground surface can be also estimated. <P>COPYRIGHT: (C)2006,JPO&NCIPI

Description

  The present invention acquires three-dimensional terrain data using a laser scanner surveying instrument mounted on an aircraft, detects minute changes in terrain contours over time, and estimates ground excavation and backfilling locations. The present invention relates to a system for detecting illegal dumping points.

  It is well known that illegal dumping of waste has become a major social problem in recent years. There are several measures to deal with the waste disposal and cleaning law (so-called “Waste Treatment Law”) and the establishment of various laws related to the promotion of recycling, but it is still illegal in mountainous areas. The dumping is unending.

  In each local government, surveillance personnel board a helicopter and detect illegal dumping points by regular visual inspections. However, in this method, the monitoring personnel tend to be uncomfortable due to the swinging and vibration of the helicopter. Also, unless it is a very large-scale illegal dumping, it is difficult to identify the location, and since the view will be different if the navigation direction changes, the part that depends on the experience of the observer is large, and objective judgment materials Difficult to get. In particular, if an illegal dumping site is backfilled with earth or sand or hidden by vegetation or the like, it is impossible to detect illegal dumping by visual inspection. Even if a suspicious situation is found, there are many cases where the landowner's permission cannot be obtained due to the lack of objective judgment materials and the site cannot be investigated.

  Although it is possible to analyze satellite images taken by artificial satellites, even if it is possible in principle, there is actually a problem with accuracy, and this method detects unless it is illegally dumped on a very large scale. Have difficulty. In the case of small-to-medium scale terrain modification or hidden by trees, it cannot be detected at present. Recently, there has also been a tendency to reduce the dumping scale at one place and disperse the dumping places, and it is not possible to cope with such sophisticated illegal dumping.

  Although it is conceivable to install a sensor such as a surveillance camera, it is necessary to predict an illegal dumping location in advance, and the illegal dumping is not necessarily performed at the sensor installation location. Therefore, even though sensors such as surveillance cameras are effective for detecting illegal traders, they are ineffective for detecting illegal dumping places such as forests.

In addition, a method for remotely investigating the type distribution of illegally dumped items by airborne MSS observation has been proposed (see Patent Document 1). In order to make this survey method function effectively, an illegal dumping location is first identified. There is a need.
JP 2003-279415 A

  The problem to be solved by the present invention is that it is difficult to understand if it is backfilled or covered with trees, because it is not possible to obtain objective judgment material for illegal dumping by periodic patrols by visual inspection. The analysis of the obtained satellite image has a problem in accuracy, and a sensor such as a surveillance camera is incapable of detecting an illegal dumping point.

  The present invention mounts a laser scanner surveying instrument on an aircraft, flies over the monitored area, records information on the aircraft's own position and inclination, and irradiates the laser beam on the ground to measure the repetition time of the reflected echo. 3D terrain data is acquired from the above, and a topographic map is created. By detecting minute changes in terrain contours over time, topographical alterations are extracted, and illegal dumping points are detected based on this. This is a dumping point detection system.

  Determine the reflection intensity of the laser beam, create a distribution map, detect the location where the metallic material is dumped on the surface by detecting the location where the reflection intensity is abnormal, and compare the estimated location where the metallic material is discarded and the location where the topography has been altered It is also effective to detect illegal dumping points based on this.

  According to the illegal dumping spot detection system according to the present invention, a topographic map is created by using a laser scanning surveying instrument mounted on an aircraft to create a topographic map, and fine changes with time of topographic contour lines are detected. Since it is a method, it is possible to remove ground noise such as trees and perform high-accuracy analysis, and to obtain objective judgment materials for illegal dumping locations. Even in areas where dumpers are not easily accessible, such as mountainous areas, illegal dumping sites can be detected efficiently.

  The aircraft is equipped with a laser scanner surveying instrument, flies over the surveillance area, records information on the aircraft's own position and tilt, and irradiates the laser beam on the ground to measure the repetitive echo repetition time. Dimensional data is acquired to create a topographic map, and terrain modification points are extracted by detecting minute changes in terrain contours over time, and illegal dumping points are detected based on this. At that time, the reflection intensity of the laser beam is obtained, a distribution map is created, and the location where the metallic material is dumped on the surface is detected by detecting the location where the reflection intensity is abnormal. It is also possible to detect illegal dumping points based on this.

  FIG. 1 is a flowchart showing an embodiment of an illegal dumping monitoring system including an illegal dumping point detection system according to the present invention. First, a monitoring area is selected by a monitoring area selection system. This usually begins with collecting and organizing various information. For example, topographic maps (old maps), aerial photographs, national land maps, forest basic maps, city planning maps, housing maps, etc. as basic conditions, natural conditions such as vegetation, topography, geology, water systems, and social conditions Collect and organize data such as the density of residential areas, road positions, road width, and past dumping locations and dumping status as illegal dumping history into a database. These are integrated into a GIS (geographic information system). Based on this, the department in charge of industrial waste countermeasures will select the monitoring area.

In the illegal dumping point detection system, an aircraft is equipped with a laser scan surveying instrument and flies over the surveillance area for surveying. The aircraft may be a helicopter, but a light aircraft is preferred in terms of navigation stability. In addition, the aircraft is also equipped with GPS (positioning system) and INS (posture recording system by gyro), and its own position and inclination are also obtained. For example, a laser profiler is used as the laser scan surveying instrument. This is a non-mirror that records the distance to the object and the scan angle, and products having the following performance are commercialized.
・ Flight altitude: 500-2000m
・ Scanning angle: ~ ± 20 °
Scan frequency: 28 Hz (20 °), 50 Hz (10 °)
・ Laser wavelength: 1047 nm
・ Laser beam irradiation frequency: 33000 Hz 2 points / m ² data can be collected at an altitude of 1000 m ・ Laser beam width: 0.2 mrad altitude of 1000 m and a diameter of 20 cm (footprint)
As a result, the horizontal error can be measured with an accuracy of 1/2000 or less of the flight altitude and the height error can be measured with an accuracy of 0.15 m or less. Measurement data is recorded on a hard disk drive or the like.

  As shown in FIG. 2, a laser scan surveying instrument mounted on the aircraft 10 emits laser light toward the ground surface 12, and the repetitive time of reflected echoes is measured while changing the irradiation direction. The laser beam emission position / posture angle and the distance measured by the reflected echo of the laser beam are calculated, and the absolute coordinates of the reflected point are calculated. The double pulse function is used for grasping the ground height in places where trees 14 are present. The double pulse function captures the first reflection (first pulse) and the last reflection (last pulse) of each laser beam. By using the reflected echo data of the last pulse, ground noise such as trees can be removed. The distance to the ground surface can be obtained. In addition, the flight should be carried out by selecting a period with good weather conditions in a period that requires monitoring, and observing it according to the period. Actually, surveying is repeated after a certain period for history management.

  In this way, the absolute coordinates of the reflection point are calculated using the reflection echo of the laser beam, so that the three-dimensional data of the terrain is acquired and the terrain map (terrain contour map) is created. Then, by comparing the terrain contours at the time of measurement with the data of the already accumulated geographic information system, the temporal change history of the terrain contours is captured. If contour lines with a pitch of 1 to 2 m are drawn at a scale of 1/1000 to 1/2500, the accuracy in the vertical direction is about ± 10 cm. Accordingly, it is possible to detect minute topographical changes based on illegal dumping, such as excavation and backfilling, as topographic contour changes. For example, if the current topographic contour map as shown in FIG. 3B is obtained with respect to the past topographic contour map as shown in FIG. It can be seen that a fine terrain change has occurred at the location indicated by the symbol x (the broken line represents the past terrain contour). This comparison result can also be obtained automatically by processing with a computer. In addition, by examining the contour lines of the terrain, it can be determined to some extent whether the cause of the terrain deformation is due to a natural phenomenon or an artificial one. Compared with other information such as road construction, there is a possibility of illegal dumping. High places can be extracted.

  In addition, the reflection intensity of the laser light is obtained, a distribution reflection intensity diagram thereof is created, and the location where the metallic substance is discarded on the ground surface can be estimated by detecting the location where the reflection intensity is abnormal. Therefore, it is also possible to compare the metallic material dumping location thus obtained with the landform alteration location (such as excavation and backfilling of natural ground) and thereby identify the illegal dumping location. The identified illegal dumping locations will be regularly patroled, installed surveillance cameras, etc., registered in the database, and managed for history. These pieces of information are added to the geographic information system and accumulated as the latest information. Therefore, the stored information can be taken out and used at any time.

  As described above, as an existing technique, there is an illegal dumping substance content estimation system based on an on-board MSS observation as disclosed in Patent Document 1. This is because the thermal infrared radiation radiated from the ground surface is observed in the morning and afternoon from the sky over almost the entire survey area, thereby obtaining the relative temperature distribution of the ground surface in the morning and afternoon, and the absolute The temperature is measured on-site, the temperature of the relative temperature distribution is corrected, and a corrected surface temperature difference image (thermal infrared difference image) is created between the morning and afternoon, and the contents of illegal dumping (heat generation) from the magnitude of the temperature difference This is a method for estimating the buried area and estimating the buried area. By incorporating such an illegal dumped substance content estimation system into the illegal dumping point detection system according to the present invention, it is possible to simultaneously grasp the contents of the illegal dumped substance and to constitute an illegal dumping monitoring system.

  In any case, if an illegal dumping point is detected by the system according to the present invention, it is possible to collect sighting information or install a sensor such as a surveillance camera to identify an illegal trader.

The flowchart which shows an example of the illegal investment monitoring system which concerns on this invention. Explanatory drawing of the landform measurement method by laser surveying. The conceptual diagram which shows the example of an analysis result.

Explanation of symbols

10 Aircraft 12 Tree 14 Ground

Claims (2)

  The aircraft is equipped with a laser scanner surveying instrument, flies over the surveillance area, records information on the aircraft's own position and tilt, and irradiates the laser beam on the ground to measure the repetitive echo repetition time. Illegal dumping location detection system, which acquires dimensional data, creates topographic maps, detects topographical changes by detecting minute changes in topographic contours over time, and detects illegal dumping locations based on this . Determine the reflection intensity of the laser beam, create a distribution map, detect the location where the metallic material is dumped on the surface by detecting the location where the reflection intensity is abnormal, and compare the estimated location where the metallic material is discarded and the location where the topography has been altered The illegal dumping location detection system according to claim 1, wherein the illegal dumping location is detected based thereon.

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