JP3683782B2 - Distance measuring apparatus and method - Google Patents

Description

この処理が、被撮影物体距離計算処理３１１で実行される計算処理である。
【００１５】
図４に示すように、道路から異なる距離に２つの建物（２１０，２２０）がある場合に、車両２００に設置した２台のラインセンサカメラで撮影された長尺画像の補正後の長尺画像を図５に示す。
図５に示す２０１が、車両２００の進行方向に向かって前方を向いている（カメラ方向１）ラインセンサカメラで撮影された補正後の長尺画像、２０２が、車両２００の進行方向の後ろ方向を向いている（カメラ方向２）ラインセンサカメラで撮影された補正後の長尺画像である。
長尺画像２０１、長尺画像２０２のどちらも、左が時間的に先に得られた画像、右は時間的に後に得られた画像を示し、車両２００の進行方向に向かって前方を向いているラインセンサカメラで撮影された補正後の長尺画像２０１の方で、先に建物（２１０，２２０）が撮影される。
この場合に、建物（２１０，２２０）の側面は、どちらか一方のラインセンサカメラでしか撮影されない。
２０３は、前述の画像照合照合（図３の３１０）で、対応づけられた建物（２１０，２２０）場所を示す。
この図５から理解できるように、距離の違いにより、対応付けられる画像の位置が異なり、遠い建物ほど、得られる長手方向の距離（ｔ方向のずれ）も大きい。
【００１６】
前述した移動量補正画像１（３０４）および移動量補正画像２（３０５）は、同一の物体を撮影した部分では、局所的な画像としてｘ方向、ｔ方向共に同じ縮小率で得られることになる。
ｔ方向は、元々物体の大きさを反映している。
そこで、ｘ方向も同じ比率、すなわち、撮影される距離が同じとなることを、図６、図７、図８を用いて説明する。
図６は、移動方向と平行する壁が被撮影物体であると想定した図である。
同図において、４０１は撮影位置１、４０２は被撮影物体、４０３は撮影位置１からの撮影方向、４０４はカメラ角度１、４０５はカメラ角度２、４０６は撮影位置１からカメラ角度１で撮影される位置、４０７は撮影位置２からカメラ角度２で撮影される位置、４０８は移動方向、４０９は撮影位置２、４１０は撮影位置からの撮影方向、４１１は撮影位置２からカメラ角度１で撮影される位置、４１２は撮影位置２からカメラ角度２で撮影される位置、４１３は同一物体検知距離、４１４は撮影物体距離である。
【００１７】
ここで、カメラ角度１（４０４）と、カメラ角度２（４０５）とは同じ角度である。
このため、撮影位置１（４０１）、撮影位置１（４０１）からカメラ角度１で撮影される位置４０６と、撮影位置２（４０９）とで構成される三角形は二等辺三角形である。
従って、この同一の物体が撮影される距離、即ち、位置４０６から撮影位置１（４０１）までの距離と、位置４１２から撮影位置２（４０９）までの距離とは同じになる。
つまり、２台のラインセンサカメラから被撮影物体４０２までの撮影距離は同じとなる。
なお、ｔ方向の大きさは、物体の横方向の大きさにのみ依存する。したがって、２台のラインセンサカメラのいずれでも同じ幅となる。
このため、みかけのｘ方向の物体縮小率も同じとなり、移動量補正画像１（図３の３０４）と、移動量補正画像２（図３の３０５）のライン毎の画像対応づけは、拡大縮小を必要としない簡単な比較で得ることができる。
例えば、単純な差分処理、相関値計算なとが考えられる。
また、ある物体の距離を測定したい場合、その物体はある位置に存在する。
従って、画像対応づけを１ラインで行う必要はなく、一般的な画像処理手法としての対応づけ手法も利用することができる。
【００１８】
対応づけが終れば、画像移動量定数（図３の３０６）から対応づけられた物体の距離を計算できる。
即ち、撮影位置１（４０１）から撮影物体までの撮影方向４０３の距離、および撮影位置２（４０９）から撮影物体までの撮影方向４１０の距離は、前述の（１）式に示すように、同一物体検知距離４１３の半分の距離と、カメラ角度１（またはカメラ角度２）のコタンジェント（ｃｏｔ）を掛け合わせた値として計算できる。
撮影された各物体の撮影位置からの距離を撮影できるため、これらの情報を統合すると、撮影位置から撮影された物体までの配置情報が復元できる。
例えば、上から見た場合、道路から建物までの距離が得られるということである。
なお、被撮影物体が移動方向に平行な場合に限らない。
ある被撮影物体を撮影する場合、それぞれのラインセンサカメラで撮影した被撮影物体は異なる位置から撮影されるにも係わらず、同じ距離だけ離れた場所から撮影される。
【００１９】
図７は、移動方向とは平行しない被撮影物体を撮影した場合を示す。
同図において、５０１は移動経路（または、移動ライン）、５０２は移動方向、５０３はカメラ角度１、５０４はカメラ角度２、５０５は被撮影物体、５０６は同一物体検知距離１、５０７は同一物体検知距離２、５０８は撮影物体距離１、５０９は撮影物体距離２である。
図７に示す場合でも、撮影された１つの被撮影物体は同じ大きさ画像として得られる。
図８は、その理由を簡易に示した図であり、図７の必要な線のみを抜き出したものである。
３角形ＡＢＣおよび３角形ＤＦＥは相似の二等辺三角形となる。
このため、ある物体を撮影した場合、常に同じ距離から物体を撮影でき、したがって、同一物体は、同一の大きさで撮影することができる。
このため、撮影された１つの被撮影物体は同じ大きさの画像として得られる。
【００２０】
すでに、移動方向の１ラインは、画像移動量定数（図３の３０６）で記述できるように補正されているため、同一の物体はほぼライン方向および長尺方向にも同一の大きさで撮影される。
画像照合処理３１０は、以上のようにすでに同一物体が同じ大きさで撮影されているので、移動量補正画像１（図３の３０４）、および移動量補正画像２（図３の３０５）との間で、局所的な照合を繰り返すことで画像の対応付けを行うことができる。
なお、被撮影物体の距離が連続しない場合、例えば、図４に示すように、手前の建物が終り、奥の建物が見える場合には、カメラ角度１では撮影できるが、カメラ角度２では撮影できない場所が発生する。
つまり、対応付けが不可能な領域も発生するが、これを想定した対応付けを行えば、対応付けが得られないことが距離の不連続を意味するため、問題は発生しない。
【００２１】
図９、図１０は、ラインセンサカメラの移動が直進でない場合にも、本実施の形態の距離測定方法が適用可能であることを説明するための図である。
図９は、ラインセンサカメラの移動経路が完全に円弧を描く場合、図１０は、ラインセンサカメラの移動経路が円弧でない場合を示している。
この図９、図１０において、７０１，８０１は撮影位置１、７０２，８０２は撮影位置２、７０３，８０３は被撮影物体、７０４，８０４は撮影物体距離である。
被撮影物体７０３から撮影位置１（７０１）および撮影位置２（７０２）までの距離は、図９に示すように、ラインセンサカメラの移動が円弧である場合は完全に一致する。
しかし、図１０のように、ラインセンサカメラの移動が円弧とならない場合は一致しない。
しかし、近似的には円弧と見なせる場合が多く、撮影位置１（８０１）および２（８０２）から被撮影物体８０３までの距離は近似的に等しくなる。
この場合、移動距離ではなく、正確な撮影位置と時間を得ておく必要があることは勿論である。
【００２２】
図１１は、ラインセンサカメラを実際に二台取りつける場合のラインセンサカメラ方向と配置の可能性を示すものである。
これは、実際には、同一箇所にラインセンサカメラを設置することが不可能であるので、前述した距離測定方法を実現するための補正が可能であることを説明するものである。
この図１１に示す補正方法は、時間のずれを利用して、あたかも撮影位置が１点であるように変換するのである。
例えば、図１１（ａ）、（ｂ）に示す例では、ある時点で、カメラ角度２のラインセンサカメラ２から得られる画像は、カメラ角度１のラインセンサカメラ１から得られる画像より、そのカメラ間距離分早く撮影されているとみなして、時間軸を補正する。
同様に、図１１（ｃ）、（ｄ）に示す例では、ある時点で、カメラ角度２のラインセンサカメラ２から得られる画像は、カメラ角度１のラインセンサカメラ１から得られる画像より、そのカメラ間距離分遅く撮影されているとみなして、時間軸を補正する。
【００２３】
このように、本実施の形態では、各ラインセンサカメラで得られる各ライン画像間での被撮影物体の画像の時間方向のずれを求めて、各ラインセンサカメラの移動経路から被撮影物体までの距離を測定するようにしたので、各ラインセンサカメラの移動経路から被撮影物体までの距離が近くても遠くても、正確に、かつ簡単に距離を測定することが可能となる。
また、各ラインセンサカメラで得られる被撮影物体の各ライン画像は同じ大きさとなるので、各ライン画像間での画像照合処理を簡単にすることが可能となる。
これにより、前述した特開平１１−２１８４１７号公報に記載の方法に比して、画像処理を単純化することが可能となる。
なお、前述した特開平１１−２１８４１７号公報には、本実施の形態のように、固定角度の２台のラインセンサカメラを設置することは記載されておらず、しかも、前述した特開平１１−２１８４１７号公報の方法により、画像処理が単純化するという効果は言及されていない。
【００２４】
［実施の形態２］
本実施の形態は、長尺３次元画像を生成する実施の形態である。
本実施の形態では、図１２に示すように、２台のラインセンサカメラが、半径Ｒの円周上を決められた方向に移動する。
また、２台のラインセンサカメラの撮影方向は、常に、円周の接線に垂直方向から前後に角度（θ１）傾いた状態にある。
ここで、撮影点の移動情報は、ロータリーエンコーダーなどにより取得する。次に、撮影点１（９０１）においてラインセンサカメラ１で撮影され、かつ、撮影点２（９０２）においてラインセンサカメラ２で撮影された観測点から円周の中心までの距離の計算方法を示す。
図１２のように、ラインセンサカメラを設置すると、撮影点１（９０１）から観測点Ｍまでの距離と、撮影点２（９０２）から観測点Ｍでの距離は等しくなる。
そこで、観測点Ｍと、撮影点２（９０２）と、円周の中心で作られる３角形に着目し、観測点Ｍから円周の中心Ｏまでの距離Ｌｍを求める。
【００２５】
図１３は、前記の３角形を示した図であり、交点Ｐは、観測点Ｍと撮影点２（９０２）とを通る直線と、その直線に対する円周の中心Ｏからの垂線との交点である。
ここで、円周の中心Ｏから交点Ｐまでの距離Ｌｐは、下記（２）式で求めることができる。
【数２】
Ｌｐ＝Ｒ×ｓｉｎθ１ ・・・・・・・・・・・・・・・・・・ （２）
したがって、観測点Ｍから円周の中心Ｏまでの距離Ｌｍは、下記（３）式で求めることができる。
【数３】
Ｌｍ＝Ｒ×ｓｉｎθ１／ｓｉｎ（θ１−θ２） ・・・・・・・・ （３）
ここで、角度θ１と角度θ２との関係は、常に下記（４）式で表される。
【数４】
０＜θ２＜θ１＜９０度 ・・・・・・・・・・・・・・・・・・ （４）
【００２６】
つまり、接線の垂直方向の傾きθ１を定めると、撮影点１（９０１）でラインセンサカメラ１に写る観測点Ｍは、撮影点１（９０１）から円周上で２πＲ×（２θ１／３６０）未満の距離の撮影点２（９０２）でラインセンサカメラ２に必ず撮影される。
このように、観測点Ｍの探索範囲を限定することができる。
具体的な観測点Ｍの対応付けの方法は、実施例１と同様である。
これにより、撮影点が円周上を一周すれば、円周中心からの距離の基づく長尺３次元画像を生成することができ、都市景観のような長尺なステレオ画像を正確に得ることができる。
以上、本発明者によってなされた発明を、前記実施の形態に基づき具体的に説明したが、本発明は、前記実施の形態に限定されるものではなく、その要旨を逸脱しない範囲において種々変更可能であることは勿論である。
【００２７】
【発明の効果】
本願において開示される発明のうち代表的なものによって得られる効果を簡単に説明すれば、下記の通りである。
（１）本発明によれば、各撮影画像撮影手段の移動経路から被撮影物体までの距離が近くても遠くても、正確に、かつ簡単に距離を測定することが可能となる。
（２）本発明によれば、各ライン画像間での画像照合処理を簡単にすることが可能となる。
（３）本発明によれば、都市景観のような長尺なステレオ画像を正確に得ることが可能となる。
【図面の簡単な説明】
【図１】本発明の実施の形態１の距離測定方法を説明するための斜視図である。
【図２】図１において、カメラが搭載された車両が、左から右へ進む場合を真上から見た図に、撮影方向、およびカメラ方向を加えた図である。
【図３】本発明の実施の形態１の距離測定方法の処理手順を説明するための図である。
【図４】被撮影物体（２つの建物）の一例を示す斜視図である。
【図５】図４に示す２つの建物を、車両に設置した２台のラインセンサカメラで撮影した長尺画像の補正後の長尺画像を示す図である。
【図６】移動方向と平行する被撮影物体（壁）である場合の、本発明の実施の形態１の距離測定方法を説明するための図である。
【図７】移動方向とは平行しない被撮影物体である場合の、本発明の実施の形態１の距離測定方法を説明するための図である。
【図８】図７中の、一部を取り出して示す図である。
【図９】移動経路が円周を描く場合の、本発明の実施の形態１の距離測定方法を説明するための図である。
【図１０】被撮影物体が円弧でない場合の、本発明の実施の形態１の距離測定方法を説明するための図である。
【図１１】本発明の実施の形態１の距離測定方法において、２台のラインセンサカメラの設置方法の一例を示す図である。
【図１２】本発明の実施の形態２の距離測定方法を説明するための図である。
【図１３】図１２中の、一部を取り出して示す図である。
【符号の説明】
１０１…撮影位置、１０２，４０８，５０２…移動方向、１０３，４０２，５０５，７０３，８０３…被撮影物体、１０４，４０３，４１０…撮影方向、１０５…カメラ方向１、１０６…カメラ方向２、１０７，４０４，５０３…カメラ角度１、１０８，４０５，５０４…カメラ角度２、２００…車両、２０１、２０２…補正後の長尺画像、２０３…画像照合により対応付けられた場所、２１０，２２０…建物、３０１…画像１、３０２…画像２、３０３…位置情報、３０４…移動量補正画像１、３０５…移動量補正画像２、３０６…画像移動量定数、３０７…距離差分情報、３０８…距離計測結果、３０９…移動量補正処理、３１０…画像照合処理、３１１…被撮影物体距離計算処理、４０１，７０１，８０１…撮影位置１、４０６…撮影位置１からカメラ角度１で撮影される位置、４０７…撮影位置２からカメラ角度２で撮影される位置、４０９，７０２，８０２…撮影位置２、４１１…撮影位置２からカメラ角度１で撮影される位置、４１２…撮影位置２からカメラ角度２で撮影される位置、４１３…同一物体検知距離、４１４，７０４，８０４…撮影物体距離、５０１…移動経路（または、移動ライン）、５０６…同一物体検知距離１、５０７…同一物体検知距離２、５０８…撮影物体距離１、５０９…撮影物体距離２、９０１…撮影点１、９０２…撮影点２、Ｍ…観測点、Ｐ…交点。[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a distance measuring apparatus and method, and more particularly, to a distance measuring apparatus that photographs a captured object while moving and measures the distance to the captured object based on a long image of the captured object. Regarding the method.
[0002]
[Prior art]
Conventionally, there are a wide variety of methods for capturing an image using two cameras and restoring a three-dimensional space from the collation.
When an area sensor camera (general camera) is used, there is a problem that it is difficult to obtain an accurate result because the resolution of the area sensor camera is actually extremely lower than that of a line sensor.
A method of restoring a three-dimensional space using two line sensor cameras is also known as described in, for example, Japanese Patent Application Laid-Open No. 11-218417 or Japanese Patent Application Laid-Open No. 10-153426.
The method described in Japanese Patent Application Laid-Open No. 11-218417 (hereinafter referred to as “first method”) has two line sensor cameras in a direction perpendicular to the moving direction, and the photographing lines of the line sensor cameras are also in the same direction. In this method, the images are set so as to overlap each other, but separated from each other by a certain distance.
In the method described in Japanese Patent Laid-Open No. 10-153426 (hereinafter referred to as “second method”), two cameras are mounted on an airplane or a helicopter. Is a method of taking a picture forward of the traveling direction.
[0003]
[Problems to be solved by the invention]
The first method described above provides good distance measurement accuracy when the object to be photographed (hereinafter, the object to be photographed) is close. However, when the object to be photographed becomes far and the distance becomes large, the parallax in stereo becomes small. Therefore, there is a problem that accurate distance measurement becomes difficult.
In the second method described above, when a certain object is photographed by the first line sensor camera and the second line sensor camera, the size of the photographed object is photographed by the first camera. If you do it will be bigger.
For this reason, particularly when an object to be photographed is present in the vicinity, when the image is collated, the apparent size of the photographed object to be photographed changes, which makes it difficult to collate.
The present invention has been made to solve the problems of the prior art, and an object of the present invention is to provide a distance measuring apparatus and method in which the distance from the moving path of each captured image capturing means to the object to be captured is determined. It is an object of the present invention to provide a technique capable of measuring a distance accurately and easily regardless of whether it is close or far.
The above and other objects and novel features of the present invention will become apparent from the description of this specification and the accompanying drawings.
[0004]
[Means for Solving the Problems]
Of the inventions disclosed in this application, the outline of typical ones will be briefly described as follows.
That is, the present invention is a distance measuring device, The shooting angle is the same angle with respect to the direction perpendicular to the traveling direction, and the forward direction and the backward direction. The two image photographing means for photographing the line image of the object to be photographed while moving, the line images photographed by the two image photographing means, and the photographing position information are associated with each other. An image storage means for storing, and each line image stored in the image storage means based on position information stored in the image storage means Find the moving speed at the time of shooting the line image, determine the proportion of expansion and contraction in inverse proportion to the moving speed at that time, A movement amount correction unit that corrects a line image that does not depend on the movement speed, and each line image that is output from the movement amount correction unit and that does not depend on the movement speed are collated, and the object to be photographed between the line images Based on the image collating means for obtaining the deviation of the images in the time direction, the deviation in the time direction output from the image collating means, and the photographing directions of the two image photographing means, the two image photographing means And a distance calculating means for calculating the shortest distance from the moving path to the object to be photographed.
[0006]
Further, the present invention is a distance measuring method, The shooting angle is the same angle with respect to the direction perpendicular to the traveling direction, and the forward direction and the backward direction. While moving the two image photographing means installed in such a manner, the first image photographing means captures a line image of the object to be photographed by the two image photographing means, and each of the two image photographing means photographed by the two image photographing means. The process 2 of associating the line image with the photographing position information and storing it in the image storage means, and each line image stored in the image storage means based on the position information stored in the image storage means Find the moving speed at the time of shooting the line image, determine the proportion of expansion and contraction in inverse proportion to the moving speed at that time, The process 3 for correcting the line image independent of the moving speed is compared with the image between the line images corrected in the process 3 and independent of the moving speed, and the object image between the line images is compared. Based on the process 4 for obtaining the time direction shift, the time direction shift obtained in the process 4 and the shooting direction of the two image shooting means, the moving path of the two image shooting means And a step 5 of calculating the shortest distance to the object to be photographed.
[0007]
Book In a preferred embodiment of the invention, the photographing line for photographing each line image is vertically vertical.
In a preferred embodiment of the present invention, the two image projection means move on a circumference, and the photographing direction connects the photographing positions of the two image projection means from the center of the circumference. It is characterized by being directed in directions symmetric with respect to the line.
[0008]
According to the above means, the time-direction deviation of the captured object image between the line images obtained by the respective image capturing means is obtained, and the shortest distance from the moving path of each captured image capturing means to the captured object is measured. Thus, the distance can be accurately and easily measured regardless of whether the distance from the moving path of each captured image capturing unit to the object to be captured is short or long.
Further, according to the above means, the line images of the object to be photographed obtained by the image photographing means have the same size, so that it is possible to simplify the image matching process between the line images.
Moreover, according to the said means, it becomes possible to acquire a long stereo image like a cityscape correctly.
[0009]
DETAILED DESCRIPTION OF THE INVENTION
Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings.
Note that components having the same function are denoted by the same reference symbols throughout the drawings for describing the embodiment, and the repetitive description thereof will be omitted.
[Embodiment 1]
FIG. 1 is a perspective view for explaining the distance measuring method according to the first embodiment of the present invention.
In the present embodiment, a case will be described in which two line sensor cameras are installed in a vehicle, a building is photographed mainly on the side of the road, and the distance from the road to the building is measured.
Here, it is assumed that the vehicle travels forward, and this is the movement direction 102.
However, the moving direction 102 is an example, and even in other cases, the direction can be changed while maintaining the relationship between the moving direction and the camera as necessary.
FIG. 2 is a diagram in which the shooting direction 104 and the camera direction (105, 106) are added to the view of the vehicle mounted with the camera in FIG.
[0010]
1 and 2, reference numeral 101 denotes a shooting position of an object to be shot (here, a building beside a road) 103 at a certain point in time, and the shooting position 101 moves in a moving direction 102 with time.
An angle when the object 103 is viewed in a direction perpendicular to the moving direction 102 is an imaging direction 104.
The camera direction 1 (105) is the shooting direction of the first line sensor camera viewed from the shooting position 101, and the first line sensor camera is set so that the shooting direction faces the camera direction 1 (105). It is installed with the shooting direction 104 facing slightly forward.
An angle from the photographing direction 104 to the camera direction 1 is a camera angle 1 (107). Similarly, the second line sensor camera is installed with the camera angle 2 (108) facing backward from the shooting direction 104 so that the shooting direction faces the camera direction 2 (106).
At this time, in both the first line sensor camera and the second line sensor camera, the shooting line is in a vertical direction as shown in FIG.
Note that the shooting lines do not have to be vertically vertical as long as they are parallel to each other.
Camera angle 1 (107) and camera angle 2 (108) are the same angle.
[0011]
Next, the procedure of the distance measuring method of this embodiment will be described.
As described above, the photographing position 101 sequentially moves along the moving direction 102.
In this embodiment, when the shooting route, shooting position, or movement is linear, the distance from the reference point is accurately obtained and stored as route data.
As a specific method for obtaining such information, it is possible to obtain the above-described information using a GPS, a gyro, a rotary encoder, a speedometer, or the like.
FIG. 3 is a diagram for explaining a processing procedure of the distance measuring method according to the present embodiment. Image 1 (301) is a long image captured by the first line sensor camera, and image 2 (302) is a long image captured by the second line sensor camera.
First, this long image will be described.
In general, a line sensor camera captures one line at regular time intervals.
A long image is obtained by connecting these in the time direction to form one image.
For this reason, unlike a general image, this long image is obtained with an axis indicating space and an axis indicating time. This is represented by x and t.
The size of the x-axis is constant because it depends on the line sensor camera. In general, a line sensor camera having about 512 to 5000 sensors is used.
The t direction is in principle unlimited, so that as long an image as necessary is obtained.
Hereinafter, the direction of each line is referred to as the x direction, and the long side is referred to as the t direction.
[0012]
When a long image remains in a certain position and in a certain direction, the value obtained at one point on a certain line hardly changes over time. For this reason, a kind of “muscle” appears.
When an image (one line) is captured every certain time while the line sensor camera is moving, the “width” of the pattern appearing in the obtained long image, that is, the change in the t direction is the width of the object to be photographed. It depends on the moving speed of the line sensor camera.
When the moving speed of the line sensor camera is slow, the “width” in the long image is extended, and when the moving speed of the line sensor camera is fast, the “width” in the long image is narrowed.
Thus, the expansion / contraction of the “width” of the pattern in the long image is determined by the moving speed of the line sensor camera.
The position information 303 is position information obtained by some method, and this position information 303 determines the expansion / contraction ratio of the “width” of the pattern in the long image.
If thinning is performed in inverse proportion to the speed of a long image, the long image becomes independent of the capture speed (that is, independent of the moving speed).
One line at this time can be directly related to the distance in the traveling direction by a constant uniquely determined by the shooting conditions.
The movement amount correction process 309 executes the process described above.
Of course, the movement amount correction process 309 is not necessary if the “width” of the pattern in the long image and the distance can be corrected in advance using a rotary encoder or the like.
[0013]
The movement amount correction image 1 (304) and the movement amount correction image 2 (305) are obtained in the time direction of the image 1 (301) and the image 2 (302) by using the position information 303 by the movement amount correction processing 309, respectively. It is an image (an image that does not depend on the moving speed) linked with the scale and distance information.
The image movement amount constant (306) is a coefficient that links the movement distance with the scale of the movement amount correction image 1 (304) and the movement amount correction image 2 (305).
The movement amount corrected image obtained by correcting in this way (hereinafter referred to as a corrected long image) has a special relationship.
In the x direction, the distance to the object is small and the distance is small.
In the t direction, the size reflects only the size of the object itself, and is not affected by the distance to the object.
From this result, although the long image has an incorrect aspect ratio, an object is photographed like a general image at first glance.
The image movement amount constant 306 is a constant describing the correspondence between the distance between the lines of the long image after correction and the actual movement distance, and indicates that, for example, one line corresponds to 1 mm.
[0014]
The movement amount corrected image 1 (304) and the movement amount corrected image 2 (305) are associated with each other in the image matching process 310.
The image collating process 310 collates the movement amount corrected image 1 (304) and the movement amount corrected image 2 (305), and outputs distance difference information 307 representing a deviation in the t direction of the object to be photographed.
The to-be-photographed object distance calculation processing 311 calculates the distance in the photographing direction (104 in FIG. 2) to the to-be-photographed object based on the obtained distance difference information 307, and outputs a distance measurement result 308.
When the same object is shown in the two corrected long images, the difference in the distance between the objects is larger as the distance is different.
The collation in the image collation process 310 is performed only in one direction of the corrected long image, that is, the moving direction (102 in FIG. 1).
The distance difference information 307 directly corresponds to the distance in the real space by the image movement amount constant 306.
Thereby, the actual distance (L) between the photographing position 1 (101 in FIG. 1) and the object to be photographed (103 in FIG. 1) is obtained.
From the distance difference information 307, the actual distance (L) between the photographing position 1 (101 in FIG. 1) and the object to be photographed (103 in FIG. 1), which is the distance measurement result 308, is expressed by the following equation (1). Can be sought.
[Expression 1]

This process is a calculation process executed by the object distance calculation process 311.
[0015]
As shown in FIG. 4, when there are two buildings (210, 220) at different distances from the road, the long image after correction of the long image photographed by the two line sensor cameras installed in the vehicle 200 is shown. Is shown in FIG.
5 is a long image after correction, which is taken by a line sensor camera 201 that is directed forward in the traveling direction of the vehicle 200 (camera direction 1), and 202 is a backward direction in the traveling direction of the vehicle 200. (Camera direction 2) is a long image after correction, which is taken with a line sensor camera.
In both the long image 201 and the long image 202, the left shows an image obtained earlier in time, the right shows an image obtained later in time, and faces forward in the traveling direction of the vehicle 200. The building (210, 220) is first photographed in the corrected long image 201 photographed by the line sensor camera.
In this case, the side surface of the building (210, 220) is photographed only by one of the line sensor cameras.
Reference numeral 203 denotes the location of the building (210, 220) associated with the image collation collation (310 in FIG. 3).
As can be understood from FIG. 5, the position of the associated image differs depending on the distance, and the farther the building, the greater the distance in the longitudinal direction (shift in t direction).
[0016]
The movement amount corrected image 1 (304) and the movement amount corrected image 2 (305) described above are obtained as the local images at the same reduction ratio in the x direction and the t direction in the portion where the same object is photographed. .
The t direction originally reflects the size of the object.
Therefore, it will be described with reference to FIGS. 6, 7, and 8 that the same ratio in the x direction, that is, the same shooting distance is used.
FIG. 6 is a diagram assuming that a wall parallel to the moving direction is an object to be photographed.
In this figure, 401 is a shooting position 1, 402 is an object to be shot, 403 is a shooting direction from the shooting position 1, 404 is a camera angle 1, 405 is a camera angle 2, and 406 is a shooting angle 1 to a camera angle 1. 407 is a position taken from the photographing position 2 at a camera angle 2, 408 is a moving direction, 409 is a photographing position 2, 410 is a photographing direction from the photographing position, 411 is photographed from a photographing position 2 at a camera angle 1. 412 is a position where the camera is photographed at the camera angle 2 from the photographing position 2, 413 is the same object detection distance, and 414 is the photographing object distance.
[0017]
Here, the camera angle 1 (404) and the camera angle 2 (405) are the same angle.
Therefore, the triangle formed by the shooting position 1 (401), the position 406 shot from the shooting position 1 (401) at the camera angle 1 and the shooting position 2 (409) is an isosceles triangle.
Accordingly, the distance at which the same object is photographed, that is, the distance from the position 406 to the photographing position 1 (401) and the distance from the position 412 to the photographing position 2 (409) are the same.
That is, the shooting distance from the two line sensor cameras to the object 402 is the same.
Note that the size in the t direction depends only on the size in the horizontal direction of the object. Accordingly, the two line sensor cameras have the same width.
For this reason, the apparent object reduction ratio in the x direction is the same, and the image correspondence for each line of the movement amount correction image 1 (304 in FIG. 3) and the movement amount correction image 2 (305 in FIG. 3) is enlarged or reduced. Can be obtained with a simple comparison that does not require.
For example, simple difference processing and correlation value calculation can be considered.
When it is desired to measure the distance of a certain object, the object exists at a certain position.
Therefore, it is not necessary to perform image association by one line, and an association method as a general image processing method can also be used.
[0018]
When the association is completed, the distance of the associated object can be calculated from the image movement amount constant (306 in FIG. 3).
That is, the distance in the shooting direction 403 from the shooting position 1 (401) to the shooting object and the distance in the shooting direction 410 from the shooting position 2 (409) to the shooting object are the same as shown in the above-described equation (1). It can be calculated as a value obtained by multiplying the half of the object detection distance 413 by the cotangent (cot) of the camera angle 1 (or camera angle 2).
Since the distance from the photographing position of each photographed object can be photographed, the arrangement information from the photographing position to the photographed object can be restored by integrating these pieces of information.
For example, when viewed from above, the distance from the road to the building can be obtained.
Note that the present invention is not limited to the case where the object to be photographed is parallel to the moving direction.
When a certain object is photographed, the object to be photographed by the respective line sensor cameras is photographed from a location separated by the same distance even though it is photographed from a different position.
[0019]
FIG. 7 shows a case where an object to be photographed that is not parallel to the moving direction is photographed.
In the figure, 501 is a movement path (or movement line), 502 is a movement direction, 503 is a camera angle 1, 504 is a camera angle 2, 505 is an object to be photographed, 506 is the same object detection distance 1, and 507 is the same object. Detection distances 2 and 508 are shooting object distances 1 and 509 are shooting object distances 2.
Even in the case shown in FIG. 7, one photographed object is obtained as an image having the same size.
FIG. 8 is a diagram simply showing the reason, and only the necessary lines in FIG. 7 are extracted.
The triangle ABC and the triangle DFE are similar isosceles triangles.
For this reason, when a certain object is photographed, the object can always be photographed from the same distance, and therefore the same object can be photographed with the same size.
For this reason, one captured object is obtained as an image of the same size.
[0020]
Since one line in the moving direction has already been corrected so as to be described by the image moving amount constant (306 in FIG. 3), the same object is photographed with the same size in both the line direction and the long direction. The
Since the same object has already been photographed with the same size as described above, the image collating process 310 includes the movement amount corrected image 1 (304 in FIG. 3) and the movement amount corrected image 2 (305 in FIG. 3). Images can be associated by repeating local collation between them.
If the distance of the object to be photographed is not continuous, for example, as shown in FIG. 4, when the front building is over and the back building is visible, the camera angle 1 can be photographed, but the camera angle 2 cannot be photographed. A place occurs.
In other words, an area that cannot be associated is generated, but if the association is performed assuming this, the fact that the association is not obtained means discontinuity in distance, and thus no problem occurs.
[0021]
9 and 10 are diagrams for explaining that the distance measurement method of the present embodiment is applicable even when the movement of the line sensor camera is not straight.
FIG. 9 shows a case where the moving path of the line sensor camera completely draws an arc, and FIG. 10 shows a case where the moving path of the line sensor camera is not an arc.
9 and 10, reference numerals 701 and 801 denote photographing positions 1, 702 and 802 denote photographing positions 2, 703 and 803 denote objects to be photographed, and 704 and 804 denote photographing object distances.
As shown in FIG. 9, the distances from the object to be photographed 703 to the photographing position 1 (701) and the photographing position 2 (702) are completely the same when the movement of the line sensor camera is an arc.
However, when the movement of the line sensor camera does not become an arc as shown in FIG.
However, in many cases, it can be regarded approximately as an arc, and the distances from the shooting positions 1 (801) and 2 (802) to the object 803 are approximately equal.
In this case, it is needless to say that it is necessary to obtain an accurate shooting position and time, not the moving distance.
[0022]
FIG. 11 shows line sensor camera directions and arrangement possibilities when two line sensor cameras are actually mounted.
This explains that, in practice, it is impossible to install a line sensor camera at the same location, so that correction for realizing the above-described distance measuring method is possible.
The correction method shown in FIG. 11 uses a time lag to convert as if the shooting position is one point.
For example, in the example shown in FIGS. 11A and 11B, an image obtained from the line sensor camera 2 at the camera angle 2 at a certain point in time is an image obtained from the line sensor camera 1 at the camera angle 1. The time axis is corrected assuming that the image was taken early by the distance.
Similarly, in the example shown in FIGS. 11C and 11D, an image obtained from the line sensor camera 2 at the camera angle 2 at a certain time is more than the image obtained from the line sensor camera 1 at the camera angle 1. The time axis is corrected assuming that the image was taken late by the distance between the cameras.
[0023]
As described above, in this embodiment, the shift in the time direction of the image of the object to be imaged between the line images obtained by each line sensor camera is obtained, and the movement path from each line sensor camera to the object to be imaged is obtained. Since the distance is measured, the distance can be accurately and easily measured regardless of whether the distance from the moving path of each line sensor camera to the object to be photographed is short or long.
In addition, since the line images of the object to be captured obtained by the line sensor cameras have the same size, it is possible to simplify the image matching process between the line images.
This makes it possible to simplify image processing as compared with the method described in Japanese Patent Laid-Open No. 11-218417.
Note that the above-mentioned Japanese Patent Application Laid-Open No. 11-218417 does not describe the installation of two line sensor cameras having a fixed angle as in the present embodiment, and the above-mentioned Japanese Patent Application Laid-Open No. 11-218417. The effect of simplifying the image processing by the method of Japanese Patent No. 218417 is not mentioned.
[0024]
[Embodiment 2]
In the present embodiment, a long three-dimensional image is generated.
In the present embodiment, as shown in FIG. 12, the two line sensor cameras move on the circumference of the radius R in a predetermined direction.
In addition, the photographing directions of the two line sensor cameras are always in a state where the angle (θ1) is tilted back and forth from the direction perpendicular to the circumferential tangent line.
Here, the movement information of the photographing point is acquired by a rotary encoder or the like. Next, a calculation method of the distance from the observation point photographed by the line sensor camera 1 at the photographing point 1 (901) and photographed by the line sensor camera 2 at the photographing point 2 (902) to the center of the circumference will be described. .
As shown in FIG. 12, when the line sensor camera is installed, the distance from the photographing point 1 (901) to the observation point M is equal to the distance from the photographing point 2 (902) to the observation point M.
Therefore, paying attention to the observation point M, the photographing point 2 (902), and the triangle formed by the center of the circumference, the distance Lm from the observation point M to the center O of the circumference is obtained.
[0025]
FIG. 13 is a diagram showing the triangle, and the intersection point P is an intersection of a straight line passing through the observation point M and the photographing point 2 (902) and a perpendicular from the center O of the circumference with respect to the straight line. is there.
Here, the distance Lp from the center O of the circumference to the intersection P can be obtained by the following equation (2).
[Expression 2]
Lp = R × sin θ1 (2)
Therefore, the distance Lm from the observation point M to the center O of the circumference can be obtained by the following equation (3).
[Equation 3]
Lm = R × sin θ1 / sin (θ1-θ2) (3)
Here, the relationship between the angle θ1 and the angle θ2 is always expressed by the following equation (4).
[Expression 4]
0 <θ2 <θ1 <90 degrees (4)
[0026]
That is, when the vertical inclination θ1 of the tangent is determined, the observation point M that appears in the line sensor camera 1 at the photographing point 1 (901) is less than 2πR × (2θ1 / 360) on the circumference from the photographing point 1 (901). The image is always photographed by the line sensor camera 2 at the photographing point 2 (902) at a distance of.
Thus, the search range of the observation point M can be limited.
A specific method for associating observation points M is the same as that in the first embodiment.
Thus, if the shooting point makes a round on the circumference, a long three-dimensional image based on the distance from the circumference center can be generated, and a long stereo image such as a cityscape can be obtained accurately. it can.
Although the invention made by the present inventor has been specifically described based on the above-described embodiment, the present invention is not limited to the above-described embodiment, and various modifications can be made without departing from the scope of the invention. Of course.
[0027]
【The invention's effect】
The effects obtained by the representative ones of the inventions disclosed in the present application will be briefly described as follows.
(1) According to the present invention, the distance can be accurately and easily measured regardless of whether the distance from the moving path of each captured image capturing unit to the object to be captured is short or long.
(2) According to the present invention, it is possible to simplify the image matching process between the line images.
(3) According to the present invention, it is possible to accurately obtain a long stereo image such as a cityscape.
[Brief description of the drawings]
FIG. 1 is a perspective view for explaining a distance measuring method according to a first embodiment of the present invention.
FIG. 2 is a diagram in which a shooting direction and a camera direction are added to a view from the top when a vehicle equipped with a camera travels from left to right in FIG. 1;
FIG. 3 is a diagram for explaining a processing procedure of a distance measuring method according to the first embodiment of the present invention.
FIG. 4 is a perspective view illustrating an example of an object to be photographed (two buildings).
5 is a diagram showing a long image after correction of a long image obtained by photographing the two buildings shown in FIG. 4 with two line sensor cameras installed in the vehicle. FIG.
FIG. 6 is a diagram for explaining the distance measurement method according to the first embodiment of the present invention in the case of an object to be imaged (wall) parallel to the moving direction.
FIG. 7 is a diagram for explaining the distance measurement method according to the first embodiment of the present invention in the case of an object to be photographed that is not parallel to the moving direction.
FIG. 8 is a diagram showing a part extracted from FIG. 7;
FIG. 9 is a diagram for explaining the distance measuring method according to the first embodiment of the present invention when the moving path draws a circumference.
FIG. 10 is a diagram for explaining the distance measuring method according to the first embodiment of the present invention when the object to be photographed is not an arc.
FIG. 11 is a diagram showing an example of a method for installing two line sensor cameras in the distance measuring method according to the first embodiment of the present invention.
FIG. 12 is a diagram for explaining a distance measurement method according to a second embodiment of the present invention.
13 is a diagram showing a part extracted from FIG. 12. FIG.
[Explanation of symbols]
101 ... Shooting position, 102, 408, 502 ... Moving direction, 103, 402, 505, 703, 803 ... Object to be shot, 104, 403, 410 ... Shooting direction, 105 ... Camera direction 1, 106 ... Camera direction 2, 107 , 404, 503 ... Camera angle 1, 108, 405, 504 ... Camera angle 2, 200 ... Vehicle, 201, 202 ... Long image after correction, 203 ... Location associated by image matching, 210, 220 ... Building , 301 ... Image 1, 302 ... Image 2, 303 ... Position information, 304 ... Movement amount correction image 1, 305 ... Movement amount correction image 2, 306 ... Image movement amount constant, 307 ... Distance difference information, 308 ... Distance measurement result 309: Movement amount correction processing, 310: Image collation processing, 311: Object distance calculation processing, 401, 701, 801: Shooting position 1, 406: Shooting The position taken from the position 1 at the camera angle 1, 407... The position taken from the position 2 to the camera angle 2. 409, 702, 802. Position, 412: Position captured at camera angle 2 from shooting position 2, 413: Same object detection distance, 414, 704, 804 ... Shooting object distance, 501 ... Movement path (or movement line), 506 ... Same object detection Distance 1, 507 ... Same object detection distance 2, 508 ... Shooting object distance 1, 509 ... Shooting object distance 2, 901 ... Shooting point 1, 902 ... Shooting point 2, M ... Observation point, P ... Intersection.

Claims (6)

Two image photographing means which are set so that the photographing angle is the same angle with respect to the direction perpendicular to the traveling direction and which is the front direction and the rear direction, and which captures the line image of the object to be photographed while moving
Image storage means for storing each line image photographed by the two image photographing means and photographing position information in association with each other;
For each line image stored in the image storage means, the moving speed at the time of shooting the line image is obtained based on the position information stored in the image storage means, and the ratio of expansion and contraction is made inversely proportional to the moving speed at that time. A moving amount correcting means for determining and correcting the line image independent of the moving speed;
Image collating means that collates each line image that is output from the movement amount correcting means and does not depend on the moving speed, and obtains a deviation in time direction of the object image between the line images;
The shortest distance from the moving path of the two image photographing means to the object to be photographed is calculated based on the time direction deviation output from the image collating means and the photographing directions of the two image photographing means. And a distance calculating device. The distance measuring apparatus according to claim 1, wherein a shooting line for shooting each line image is vertically vertical. The two image projection means move on the circumference,
3. The distance measurement according to claim 1, wherein the photographing direction is directed in directions symmetrical to each other with respect to a line connecting the photographing positions of the two image projecting units from the center of the circumference. apparatus. While moving the two image photographing means installed so that the photographing angle is the same angle with respect to the direction perpendicular to the traveling direction, the two image photographing means move the object to be photographed. Process 1 of taking a line image,
A step 2 of associating each line image photographed by the two image photographing means with photographing position information in the image storage means;
For each line image stored in the image storage means, the moving speed at the time of shooting the line image is obtained based on the position information stored in the image storage means, and the ratio of expansion and contraction is made inversely proportional to the moving speed at that time. Step 3 for determining and correcting the line image independent of the moving speed;
A step 4 of collating images between the line images that are not dependent on the moving speed corrected in the step 3 to obtain a time-direction shift of the object image between the line images;
Based on the shift in the time direction obtained in the step 4 and the photographing directions of the two image photographing means, the shortest distance from the moving path of the two image photographing means to the object to be photographed is calculated. A distance measuring method comprising: step 5; The distance measuring method according to claim 4 , wherein a shooting line for shooting each line image is vertically vertical. The two image projection means move on the circumference,
6. The distance measurement according to claim 4 , wherein the photographing direction is directed in a direction symmetrical to each other with respect to a line connecting the photographing positions of the two image projecting units from the center of the circumference. Method.

Images