JP3680243B2 - Runway shape display device and map database recording medium - Google Patents

Description

Ａ＝−(X1−Xf)＊ｒ／(ｒ−Ｚ）、Ｂ＝(Y1−Yf)＊ｒ／(ｒ−Ｚ）と置くと、式（Ｂ−４）は以下のように書き換えられる。
【００６１】
【数８】
ｘ１(θ)＝ Ａ＊sinθ ＋ Ｂ＊cosθ ・・・（Ｂ−６）
図８に示すように、車両の向きが、車線の向きに対して角度βだけ傾いている場合を考える。この場合の点ｐ１のｘ座標は、式（Ｂ−６）の曲座標のθ成分をθ＋βに置き換えることにより求められる。すなわち、下式（Ｂ−７）により、角度βに対応する点ｐ１のｘ座標が求まる。
【００６２】
【数９】
ｘ１(θ＋β)＝ Ａ＊sin(θ＋β) ＋ Ｂ＊cos(θ＋β) ・・・（Ｂ−７）
一方、点ｐ１のｙ成分については以下のように考える。高速な表示更新が必要となるのは、ある程度の高速で走行している場合であるので、βの取りうる範囲は比較的狭いと考えられる。また、水平線からの仰角φも比較的小さな値であると考えられる。この前提の下で、上記の式（Ｂ−５）のθをθ＋βに置き換え、さらなる式変形を行うと、下記のようになる。
【００６３】
【数１０】

ここで、sinφおよびsinβが共に小さいのでsinφ＊sinβ≒０とし、さらにcosβ≒１とすると、結局、下式（Ｂ−９）の結果が得られる。
【００６４】
【数１１】
ｙ１(θ＋β)≒ｙ１(θ) ・・・（Ｂ−９）
式（Ｂ−９）より、車両の進行方向が車線の方向とずれているときでも、白線上の点のｙ座標の修正は不要である。基準データのｙ座標をそのまま使っても、表示した白線と実際の白線の形状は近似しており、運転者にとっては同じに見える。
【００６５】
以上の処理を円滑に行うために、運転視点走路形状記憶部２４には、白線を構成する点データ（Ａ，Ｂ，ｙ）が格納される。すなわち、一の地点が、そこから見える白線上の点データ（Ａ，Ｂ，ｙ）の集合に関連づけられる。Ａ、Ｂは式（Ｂ−７）の係数であり、ｙは投影面上のｙ軸座標である。
【００６６】
ナビゲーション制御部１０では、車両方向の傾き角βが、ジャイロセンサの検出信号から求められる。このときに２次元地図データが参照される。傾き角βと、記憶してある係数Ａ，Ｂを式（Ｂ−７）に適用することで、ｘ(θ＋β）が求められる。また、傾きの大きさに拘わらず、ｙ座標はそのまま修正なしで使われる。すべての描画点（ｘ(θ＋β)，ｙ )を求めた後、描画点をつなぎ合わせることにより、補正後の白線画像が得られる。
【００６７】
「横ずれと傾きの両方の補正」
実際の走行中は、車線に対する車両の横ずれと、車両方向の傾きとの両方が同時に発生する。従って、横ずれ補正と傾き補正の２つの処理を両方とも行うことが好適である。具体的には、まず、基準データとして、車両が車線中央で車線方向を向いているときの白線形状を読み出す。そして、車両方向の傾きに対する補正を行い、それから横ずれに対する補正を行う。これにより、実際の状況に合致した白線形状が得られる。
【００６８】
以上に白線形状の補正処理を説明した。ここでは、主として直線道路の場合を取り上げて説明したが、道路および白線がカーブしているときでも座標変換によって白線形状を補正できる。すなわち、横ずれ検出値および傾き検出値に基づいて、視点の位置および方向を変換する処理を行えばよい。
【００６９】
本実施形態によれば、車線に対して横方向のどの位置に車両がいるときでも、実際の状況に合致した走路形状を運転者に提示できる。すなわち、車両は走路内の決まった位置を走行するわけではなく、走行位置は横方向にずれ、それに伴って視点の位置もずれる。しかし、記憶されている走路形状に対応する視点と実際の視点とがずれても、上記の変換処理により、実際の視点から見た走路形状を表示できる。
【００７０】
また、本実施形態によれば、車両の方向と車線の方向とがどのような角度を成しているときでも、実際の状況に合致した走路形状を運転者に提示することができる。すなわち、車両の進行方向は走路の方向と一致するとは限らず、記憶されている走路形状で想定されている進行方向と実際の進行方向とがずれることがある。このような場合でも、上記の補正処理によって、実際の状況に則した車両前方の走路形状を表示できる。
【００７１】
そして、横ずれと傾きの両補正を行うことにより、さらに適切な走路形状を表示できる。
【００７２】
また、上記の補正処理は、同じ地点に関して他種類の白線形状データを用意しないでも、適切な白線形状を提示できるという点では、データ量の削減にも寄与している。
【００７３】
その他、本実施形態では車両方向の補正を行うために描画点データ（Ａ，Ｂ，ｙ）を記憶しているが、横ずれの補正のみを行うのであれば単に描画点データ（ｘ，ｙ）が記憶されればよい。
【００７４】
「車種別の白線表示」
以上に説明したように、本実施形態では、道路上の各地点と関連づけて運転者の視点から見た白線形状が予め記憶されている。この白線形状を予め記憶する処理は、例えば下記のようにして行うことが好適である。
【００７５】
道路を真上から見たときの白線形状のデータ（元データ）を用意する。元データは、前述の図３の座標変換処理の素材になるデータであり、図１の地図データベース記憶部２０に格納されている。元データがナビゲーション制御部１０により読み出される。ナビゲーション制御部１０は、視点と参照点を設定し、図３の座標変換処理を行って、所望の視点から見た白線形状を求める。前述したように、地図上の各地点ごとに白線形状が求められる。求められた白線形状データは、記憶装置に格納され、図１の運転視点走路形状記憶部２４を構成する。なお、白線形状を格納できるように、ハードディスク等の読み書き可能な記憶装置が、地図データベース記憶部２０の一部または全部として設けられている。ナビゲーション制御部１０は、走路形状をディスプレイに表示するとき、ハードディスク等から白線形状を読み出して処理する。
【００７６】
ところで、実際に見える白線の形状は、車種により大きく異なる。路面の見える角度、視点の位置および仰角などが車種により大きく異なるからである。例えば、ＲＶ系の車両の視点は、スポーツカーのそれよりも大幅に高い。そこで、車種に応じて白線形状を変更することが好適であり、これにより、表示する白線と実際に見える白線を合致させることができる。
【００７７】
図９を参照すると、高精度地図データベースは、真上から見た白線形状を示す元データを保有する。ナビゲーション制御部１０は、外部から、運転者の視点の高さに関する情報を入手する。例えば、車種の情報、車高情報、または視点の高さそのものの情報が入力される。この情報は、車載機器等から入力されてもよく、ユーザにより入力装置を用いて入力されてもよい。ユーザが、好みの視点高さを選べるようにしてもよい。入力情報に基づいて、その車両の視点高さおよび適切な投影面に対応する白線形状がつくられる。これにより、車種に応じた地図データベースがつくられる。
【００７８】
上記の処理の変形例を説明する。図９の高精度地図データベースは、基準の視点の高さから見た白線形状（各地点ごと）であってもよい。つまり、予め適当な視点を基準にした白線形状データベースを一つ用意しておくのである。ナビゲーション制御部１０により、入力された視点高さの情報に基づいて、基準の白線形状データが変換され、該当車両の視点高さ（および参照点）に対応する白線形状が生成される。基準視点高さから該当車両の視点高さへと、視点の高さを変えるための座標変換処理を行えばよい。
【００７９】
「白線形状データの生成タイミング」
運転視点から見た白線形状を予め生成、記憶しておく処理は、以下の３つのいずれかのタイミングで行うことが好適と考えられる。
【００８０】
（１）各車両毎のパラメータ（視点および参照点の指定）を設定し、全データを一括変換し、変換後のデータを格納しておく。この態様には、いつでもすぐに車種特有のデータを利用できるという利点がある。
【００８１】
（２）目的地までの経路計算を行ったとき、経路上の地点の白線形状データが変換される。経路を逸脱して別の道に車両が進む可能性があるので、分岐地点などでは、案内経路のみではなく、他の周辺経路に関しても白線形状の変換処理を済ませておくことが好適である。例えば、次にくる交差点の３方向の白線形状データを事前に車種に適合するように補正する。
【００８２】
（３）自車位置周辺の地点データに対応する運転視点白線形状は、常に車種適合のための変換処理を行っておく。車両が移動するにつれて、前の変換データは捨てられ、新しく近づく地点の白線形状の変換処理が行われる。この態様によれば、経路案内中でないときでも白線形状を効率よく迅速に表示できる。
【００８３】
上記の（２）を採用すると、走路形状を提示できるのが経路案内時に限られることがある。また（３）では、制御部１０の計算処理の負荷が高くなる。従って、（１）の処理を行うことが最も好適と考えられる。
【００８４】
「地図データベース記録媒体」
本発明は、上記の走路形状表示装置以外の態様に適用されてもよい。例えば、地図データベースを記録した記録媒体の態様で本発明が実現されてもよい。記録媒体には、図１の運転視点走路形状記憶部２４に関連して説明した地図データが記録される。記録媒体は、磁気、電気、光などの任意の方法でデータを読み書きできるものでよく、例えば、ＣＤ−ＲＯＭ、ＤＶＤが適当である。地図データベースは、他のナビゲーション関連プログラムなどとともに記録媒体に収められていてもよい。さらに本発明は他の態様、例えば方法の態様に適用されてもよい。
【００８５】
【発明の効果】
以上に説明したように、本発明によれば、環境条件に影響を受けずに確実かつ迅速に、運転者の視点から見た走路形状を提示することが可能になる。
【図面の簡単な説明】
【図１】 本発明の走路形状表示装置が備えられたナビゲーション装置の構成を示すブロック図である。
【図２】 図１の運転視点走路形状記憶部が格納している走路形状情報を示す図である。
【図３】 図２の走路形状情報を予め作成する処理を示す図である。
【図４】 図１の運転視点走路形状記憶部に記憶する白線形状のデータ量を削減する方法を示す図である。
【図５】 車線に対する車両の横ずれに関して白線形状を補正する処理を示す図である。
【図６】 車線方向に対する車両方向の傾きに関して白線形状を補正する処理を示す図である。
【図７】 車線方向に対する車両方向の傾きに関して白線形状を補正する処理を示す図である。
【図８】 車線方向に対する車両方向の傾きに関して白線形状を補正する処理を示す図である。
【図９】 車種別の視点高さに適合した白線データ生成処理を示す図である。
【符号の説明】
１０ ナビゲーション制御部、１２ ＧＰＳ装置、１４ ジャイロセンサ、１６ 車速センサ、１８ 位置検出部、２０ 地図データベース記憶部、２２ ２次元地図記憶部、２４ 運転視点走路形状記憶部、３０ 入力装置、３２ ディスプレイ、３４ スピーカ、３６ ヘッドアップディスプレイ。[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a road shape display device capable of reliably and quickly displaying the shape of a road seen from the viewpoint of a driver, and the present invention relates to a medium on which a map database suitable for use in the display device is recorded.
[0002]
[Prior art]
When driving the vehicle, the driver visually grasps the shape of the road ahead of the vehicle through the windshield. However, it may be difficult to determine the shape of the road ahead due to weather conditions, the curve of the road, surrounding vehicles and buildings. In view of this, it is preferable that the vehicle is provided with a device that grasps the shape of the road ahead viewed from the driver's viewpoint, and the road shape is presented to the driver.
[0003]
Japanese Patent Application Laid-Open No. 7-57200 discloses an apparatus that detects a white line on a road from a road image taken by an in-vehicle camera and displays the detected white line. The driver can grasp the shape of the road ahead by looking at the white line displayed on the display device.
[0004]
[Problems to be solved by the invention]
However, the running road shape cannot be displayed in an environment where camera photography is difficult, for example, in fog. In some cases, a white line cannot be detected from a photographed image as on a snowy road. In addition, when there is a large vehicle ahead, the white line cannot be taken. Thus, the road condition display device using a camera has limited environmental conditions to function effectively.
[0005]
In fact, it is difficult to detect the shape of the road in an environment where it is difficult for the driver to visually understand the shape of the road, but it is difficult to detect the shape of the road in such an environment. It was difficult to play a supporting role.
[0006]
Further, in a known navigation device, a two-dimensional map in which the periphery of the vehicle is viewed from directly above is displayed. However, the shape of the road viewed from directly above is significantly different from the shape of the road seen from the driver's viewpoint. Looking at such a planar map, it is not easy for the driver to intuitively grasp the shape of the road ahead.
[0007]
Furthermore, a navigation device that displays a map in three dimensions, such as a so-called bird view, is well known. A two-dimensional map in which the vicinity of the vehicle position is viewed from directly above is displayed after being processed into a map viewed from obliquely above. However, with this type of device, screen scrolling is considerably slower than normal map display. This is probably because the amount of data processing is large because coordinate transformation such as projection transformation is performed on a large number of points, and the display target data for oblique display increases.
[0008]
Currently, lane (lane) guidance on stereoscopic display is not generally performed. However, when lane guidance is to be performed, it is required to update the display at high speed as the vehicle moves. It is not easy to respond to such a request in a process with a large calculation load and a large amount of handled data.
[0009]
The present invention has been made in view of the above problems, and an object of the present invention is to make it possible to present a runway shape viewed from the viewpoint of a driver reliably and quickly without being affected by environmental conditions.
[0010]
[Means for Solving the Problems]
In order to achieve the above object, the runway shape display device of the present invention includes a driving viewpoint runway shape representing each of a plurality of points on a road on a map and a forward runway shape viewed from the viewpoint of a vehicle driver at each point. Corresponding to the own vehicle position detected by the own vehicle position detecting means, the own vehicle position detecting means for detecting the own vehicle position, the display means for displaying the driving viewpoint running road shape, and the vehicle position detecting means. Display processing means for reading out the driving viewpoint running road shape to be read from the running road shape storage means and displaying on the display means.
[0011]
According to the present invention, the driving viewpoint runway shape corresponding to the vehicle position is read from the storage device and displayed. The road shape can be displayed even in an environment where the visibility of the driver is lowered.
[0012]
Further, according to the present invention, the driving viewpoint runway shape of the corresponding point is associated with the point data of the map. That is, a driving viewpoint runway shape is prepared in advance for each point. Therefore, when displaying the runway shape, a large amount of data processing such as reading a lot of point data and performing conversion processing is unnecessary, and the runway shape at the driving viewpoint can be displayed quickly.
[0013]
Preferably, the runway shape storage means stores, as the driving viewpoint runway shape at each position, a discrete representative point set extracted from the runway shape when looking forward from the driver's viewpoint at the corresponding position. Yes. The display processing means includes means for generating a continuous road shape based on the discrete representative point set. According to this aspect, it is possible to reduce the amount of data to be stored by the road shape storage means. Since the driving viewpoint runway shape data is prepared for each point data, it is possible to avoid a situation in which the amount of data becomes enormous.
[0014]
Preferably, the display processing means selects a driving viewpoint running road shape to be read from the storage means based on a running road around the own vehicle position or a scheduled traveling road. By selecting a road that has a high possibility of actually traveling, efficient processing can be performed.
[0015]
Preferably, the vehicle includes a lateral deviation detecting means for detecting lateral deviation of the vehicle with respect to the road. In the display processing means, the driving viewpoint running road shape corresponding to the vehicle position read from the running road shape storage means is coordinate-converted into the running road shape seen from the laterally shifted viewpoint based on the lateral deviation. This makes it possible to present the driver with a road shape that matches the actual situation. That is, the vehicle does not travel at a fixed position on the road, but the travel position shifts in the lateral direction, and the viewpoint position shifts accordingly. According to the present invention, even if the viewpoint corresponding to the stored track shape is different from the actual viewpoint, the track shape viewed from the actual viewpoint can be displayed.
[0016]
In addition, it preferably includes an inclination detecting means for detecting an inclination of the vehicle direction with respect to the road direction. In the display processing means, the driving viewpoint running road shape corresponding to the vehicle position read from the running road shape storage means is coordinate-converted to the running road shape seen from the tilted viewpoint based on the inclination. This aspect also makes it possible to present the driver with a track shape that matches the actual situation. In other words, the traveling direction of the vehicle does not always coincide with the direction of the road, but according to the present invention, even if the vehicle direction assumed in the stored road shape and the actual vehicle direction deviate, The road shape in front of the vehicle can be displayed according to the situation.
[0017]
Preferably, the display means is a head-up display that displays an image on a windshield of a vehicle. Since the driver's feeling when viewing the display of the runway shape matches the actual driving feeling, the support effect for the driver increases.
[0018]
Preferably, the driving viewpoint runway shape is data indicating a shape of a line representing a lane drawn on the runway. A lane display line (typically a white line) is an appropriate index representing the shape of the road. By applying the present invention to lane guidance, update display can be performed at high speed, so that easy-to-understand guidance can be provided to the driver.
[0019]
Another aspect of the present invention is a map data recording medium in which a road map database is recorded. In the map database, each of a plurality of points on the road is associated with a driving viewpoint runway shape representing a road shape ahead of the vehicle driver at each point viewed from the viewpoint of the vehicle driver.
[0020]
DETAILED DESCRIPTION OF THE INVENTION
DESCRIPTION OF EXEMPLARY EMBODIMENTS Hereinafter, preferred embodiments (hereinafter referred to as embodiments) of the invention will be described with reference to the drawings. In the present embodiment, the runway shape display device of the present invention is provided integrally with an in-vehicle navigation device.
[0021]
FIG. 1 is a block diagram showing the configuration of the navigation device of this embodiment. The navigation control unit 10 controls the entire apparatus and performs navigation-related processing such as route calculation and route guidance. The control unit 10 also functions as display processing means of the present invention.
[0022]
The navigation control unit 10 is connected to a GPS (global positioning system) device 12, a gyro sensor 14, and a vehicle speed sensor 16. Based on the input signals from these sensors, the vehicle position detection unit 18 of the control unit 10 obtains the position of the vehicle. As is well known, the GPS device 12 obtains its own vehicle position from radio waves transmitted from an artificial satellite. The vehicle position is captured using the traveling direction and speed detected by the gyro sensor 14 and the vehicle speed sensor 16. It is also preferable to perform map matching using map data stored in the map database storage unit 20.
[0023]
The navigation control unit 10 performs navigation processing using the vehicle position detected by the position detection unit 18. When the user inputs a travel destination using the input device 30, the control unit 10 searches for and sets a route from the vehicle position to the destination. The route calculation is performed by processing such as Dijkstra method using map data stored in the two-dimensional map storage unit 22 of the map database storage unit 20. A map around the vehicle position is read from the two-dimensional map storage unit 22 and displayed on the display 32 as display means. The set route is displayed separately from other roads. In addition, a voice guidance notifying the course at the intersection is output from the speaker 34 as appropriate.
[0024]
`` Display runway shape ''
As a feature of the present embodiment, the map database storage unit 20 has a driving viewpoint runway shape storage unit 24, and this storage unit 24 is one aspect of the runway shape storage means of the present invention. In the memory | storage part 24, each point on a road is linked | related with the driving viewpoint runway shape of this invention showing the forward runway shape seen from a driver | operator's viewpoint at the applicable point.
[0025]
With reference to FIG. 2, the memory | storage information of the driving | operation viewpoint runway shape memory | storage part 24 is demonstrated concretely. A plurality of points a1 to a4 and b1 to b4 are set on opposite lanes A and B on the road. The memory | storage part 24 has memorize | stored the data of the runway shape seen from the driver | operator's viewpoint at each point. In this embodiment, the white line shape drawn on the road is used as runway shape information. The driver can easily grasp the runway shape from the white line display. Further, if the white line shape is applied, the amount of stored data and the amount of processed data can be reduced. From this point of view, the white line shape is adopted as the runway shape.
[0026]
In FIG. 2, at the point a1 on the first lane A, the road ahead is a straight line. Therefore, a white line shape representing a straight line is associated with the point a1. At the point a2, since the road ahead is a right curve, the white line shape of the right curve is associated with the point a2. On the other hand, at the point b1 on the second lane B facing the first lane A, the road ahead is the left curve, so the white line shape of the left curve is associated with the point b1. The point b3 is associated with a straight white line shape.
[0027]
Point a2 and point b3 are the same place on the road, but belong to the opposite lane. Therefore, the forward runway shapes of the points a2 and b3 are different, and the stored white line shapes are also different. In this way, different white line shapes are stored depending on the lane direction.
[0028]
The white line shape data is created and stored in advance by projection conversion as shown in FIG. Set the perspective of the driver with a standard physique when the standard vehicle is in the middle of the lane. A large number of points P1 to Pn are set on the white line of the road ahead of the viewpoint. A point p1 (x1, y1) obtained by projecting one point P1 (X1, Y1, Z1) on the projection plane is obtained with the viewpoint as a reference. By similar coordinate transformation, a point to be displayed on the projection plane is obtained from other points on the white line. In this way, the front white line shape seen from the viewpoint shown in FIG. 3B is generated.
[0029]
Returning to FIG. 1, when the driver operates the input device 30 to instruct the display of the runway shape, the navigation control unit 10 performs a driving viewpoint runway shape display process. First, the vehicle position is determined. Then, the white line shape stored in advance in association with the obtained position is read from the driving viewpoint runway shape storage unit 24. At this time, as described with reference to FIG. 2, the white line shape corresponding to the traveling direction of the vehicle is read out. The read white line shape is displayed on the head-up display 36 under the control of the navigation control unit 10. As is well known, the head-up display 36 is a device that projects an image on the windshield of a vehicle.
[0030]
As described above, according to the present invention, the running road shape can be reliably displayed even under environmental conditions where the driver's visibility is low. For example, in weather such as fog, it is difficult to grasp the runway shape by visual observation. Similarly, when the road is covered with snow or when a large vehicle is in front, it is difficult to grasp the shape of the runway. Under such circumstances, it is difficult to grasp the shape of the runway from the captured image even if the front landscape is photographed by the camera. However, according to the present invention, the runway shape is displayed using the detected vehicle position and the stored information, so the runway shape can be reliably displayed even under the environmental conditions described above.
[0031]
In the present embodiment, white line shape data for each point is generated and prepared in advance. Here, it is assumed that a white line shape has not been prepared in advance. In this case, the white line shape generation processing described with reference to FIG. 3 must be performed in real time. In addition to reading the data of the vehicle position from the storage device, prefetching of data indicating a point on the white line ahead of the vehicle position is further performed. The pre-read data is subjected to coordinate conversion with respect to the viewpoint origin, and projected and converted on the projection plane, and the obtained image is displayed. A large amount of data processing is required, and quick and appropriate display update becomes difficult.
[0032]
On the other hand, according to the present invention, prefetching of data is unnecessary, and only data related to the current location need be read from the storage device. This is because the white line shape seen from the driver's viewpoint is already prepared as part of the point data. There is no need for coordinate conversion processing of the pre-read data group. Therefore, the white line shape can be displayed quickly. The prompt display of the white line is also suitable for guiding the lane change.
[0033]
In addition, preferably, the navigation control unit 10 selects a white line shape to be read from the driving viewpoint running road shape storage unit 24 based on a running road around the vehicle position or a scheduled traveling road. The scheduled travel route is determined from a set route used for route guidance. Efficient processing can be performed by narrowing down the data read from the storage device on the basis of the actual traveling path with high possibility of traveling.
[0034]
In the present embodiment, the white line shape is displayed on the head-up display 36 as described above. Therefore, since the driver's feeling when viewing the display of the running road shape matches the actual driving feeling, a greater driving support effect can be obtained. Of course, the white line shape may also be displayed on the display 32. In addition to the white line shape, other information such as signs on and around the road may be displayed.
[0035]
"Treatment for multi-lane roads"
On a road having a plurality of lanes in one direction, the entire lane shape may be displayed, but it is also preferable to display the lane shape in which the host vehicle is traveling. In recent years, a highly accurate position detection technique called RTK (Realtime Kinematic) -GPS has been proposed. Using such a method, the traveling lane is determined. The driving viewpoint runway shape storage unit 24 stores a white line shape for each lane and displays corresponding data.
[0036]
"Processing for roads without a centerline"
You cannot define your own lane on a road without a center line. Therefore, the white line shape of each point on the road when viewed in both directions is stored. Then, the white line shape corresponding to the traveling direction is read and displayed.
[0037]
"Reduce the data volume of the white line shape of the driving viewpoint"
The white line shape shown in FIG. 3 is a set of points on the projection plane. If the data of the coordinate conversion result of FIG. 3 is simply stored for each point, the amount of stored data becomes enormous. Therefore, it is preferable to reduce the amount of data that the driving viewpoint track shape storage unit 24 should store as shown in the following (1) to (3).
[0038]
(1) Data is thinned and stored
Data can be reduced by appropriately thinning out data from a set of a large number of points showing a white line shape and leaving representative points. Referring to FIG. 4A, even if the points are set at regular intervals on the actual road, the distance between the points becomes narrower as the distance increases on the projection plane. Therefore, the farther away, the more points are thinned out, and the interval between representative points is increased. For example, it is preferable to increase the interval between representative points in an exponential manner in order of every other, every second, every fourth, and so on. If such processing is performed, the amount of data can be effectively reduced while maintaining the white line shape that is close to the actual appearance for the driver. At the time of white line display, the navigation control unit 10 reads out a set of representative points and connects them appropriately to obtain a continuous white line shape.
[0039]
(2) Approximate curve is obtained from calculation result and its parameters are stored
Referring to FIG. 4B, for example, the white line shape on the projection surface is approximated to a quadratic curve or a straight line. Then, a quadratic curve or straight line parameter is stored. Such processing can also reduce the amount of data without impairing the white line shape of the driver. In the display process, the navigation control unit 10 reads the parameters as the running path shape information and generates image data according to the parameters.
[0040]
(3) Approximate the white line shape to some straight lines and store the coordinates of end points and intersection points
As shown in FIG. 4C, the white line shape is approximated to a plurality of straight lines. From the same viewpoint as (1), it is preferable to replace a large number of points with one straight line as the distance increases. The end points of the foremost and last straight lines and the coordinates of the intersections of the straight lines are stored as white line shapes. The form of data is basically a representative point set similar to (1). In the display process, the representative point set is read out and connected by a straight line.
[0041]
In the above, (1) and (3) are one form of the aspect of the present invention for storing discrete representative point sets extracted from the running road shape. The navigation control unit 10 generates a continuous runway shape based on the representative point set.
[0042]
"Correction of white line shape"
The driving viewpoint runway shape storage unit 24 stores a white line shape as a reference. This reference shape is a white line shape when the vehicle is in the center of the traveling lane and the direction of the lane coincides with the direction of the vehicle (traveling direction). However, in other situations, the white line shape as seen from the driver's point of view is different. Therefore, if the white line shape is corrected according to the position and direction of the vehicle as described below, the actual white line shape and the image can be matched, and more convenient information can be provided to the driver. Here, it is assumed that the white line shape is constituted by the above-described set of representative point data.
[0043]
"Correction for vehicle lateral deviation (offset)"
First, the white line shape correction process when the vehicle is running at a position shifted laterally from the center of the lane will be described. In order to simplify the explanation, it is assumed that the road is straight and the vehicle direction coincides with the lane direction (parallel).
[0044]
FIG. 5A shows a standard white line shape stored in the driving viewpoint runway shape storage unit 24, that is, a white line shape seen from the center of the lane. On the projection plane, the distance between the two white lines is L2 on the near side and L1 on the far side. When the x-axis is set in the horizontal direction on the screen and the y-axis is set in the vertical direction, the white line is inclined by an angle α with respect to the y-axis.
[0045]
FIG. 5B shows a white line shape that can be seen when the vehicle is at a position crossing the left white line. The horizontal interval between the white lines is the same as that in FIG. The direction of the left white line coincides with the vehicle direction (= y axis).
[0046]
FIG. 5C shows a white line shape that can be seen from the driver's seat in a general situation. Assume that the actual road width is W and the actual offset amount from the road center is Δw. When the vehicle is offset by Δw, it is assumed that the inclination angle of the left white line is α ′ on the projection plane. Using the white line inclination angle α of the reference data (FIG. 5A), the angle α ′ is obtained by the following equation (A-1).
[0047]
[Expression 1]
α ′ = α × (1-Δw / (W / 2)) (A-1)
By using this equation, display data at various offset positions can be created from the reference display data by simple calculation.
[0048]
An example of a method for actually obtaining the coordinates of the two end points p1 to p4 of the two white lines in FIG. The coordinates before and after correction of the point p1 are (x1, y1) and (x1a, y1), respectively (the same applies to the points p2 to p3). Since the lateral shift is targeted, it is not necessary to correct the y coordinate.
[0049]
"Step 1" Find the image center. The center deviation amount ΔL is obtained by the following equation (A-2).
[0050]
[Expression 2]
ΔL = L2 * Δw / W (A-2)
"Step 2" Display positions of points p1 and p2 (end points on the near side of both white lines) are obtained. The corrected x coordinate (x1a) of the point p1 is obtained by the following equation (A-3) from the stored reference x coordinate (x1) of the point p1. Similarly, the corrected x coordinate (x2a) of the point p2 is also obtained.
[0051]
[Equation 3]
(x1a) = (x1) −ΔL (A-3)
“Step 3” α ′ is obtained using the above-described equation (A-1). Then, the corrected x coordinate (x3a) of p3 is obtained from α ′.
[0052]
[Expression 4]
(x3a) = (x1a) + sin (α ′) * (y1−y3) (A-4)
"Step 4" The x coordinate (x4a) of the point p4 that is laterally separated from the point p3 obtained in step 3 by L1 is obtained.
[0053]
[Equation 5]
x4a = x3a + L1 (A-5)
As described above, since the offset is targeted, correction of the y coordinate is unnecessary. Thus, since the coordinates of the points p1 to p4 are obtained, a straight line connecting p1 and p3 and a straight line connecting p2 and p4 are drawn. The generated image has a white line shape obtained by correcting the offset of the vehicle.
[0054]
In order to simplify the explanation, a straight road has been taken up and explained. However, even when the road is curved, the coordinate conversion process may be performed basically in the same way. What is necessary is just to obtain | require inclination-angle (alpha).
[0055]
In the present embodiment, it is preferable to detect the amount of lateral deviation with respect to the center of the lane using a high-precision positioning technique such as the above-described RTK-GPS. In addition, a camera that captures a white line or the like under the foot of the vehicle may be provided, and a lateral shift may be detected from a captured image of the camera. If it is an image of the foot, it can be photographed even under bad weather conditions such as fog.
[0056]
In the present embodiment, the vehicle position of the reference image is the center of the lane, but other positions may be the reference.
[0057]
"Correction according to vehicle direction inclination"
Here, the white line shape correction process when the direction of the vehicle is inclined with respect to the direction of the lane will be described. In order to simplify the explanation, it is assumed that the vehicle is in the center of the lane and the amount of lateral deviation is zero. It is assumed that only the direction of the vehicle is deviated from the direction of the lane by an angle β at this position.
[0058]
Consider a music coordinate system as shown in FIG. A projection surface as shown in FIG. 7 is assumed. When the viewpoint is expressed in a coordinate system with reference points by general coordinate transformation (projection transformation), it is as follows. The reference point (gaze point) is a reference point on the projection plane, for example, a point at the center of the screen. Here, the viewpoint is (Xv, Yv, Zv), and the reference point is (Xf, Yf, Zf).
[0059]
[Formula 6]
Xv = r * cosθ * cosφ + Xf (B-1)
Yv = r * sinθ * cosφ + Yf (B-2)
Zv = r * sinφ + Zf (B-3)
When the point P1 (X1, Y1, Z1) on the white line is viewed from the viewpoint, the point P1 is projected onto the point p1 (x1, y1) on the projection plane. Here, Z in the following expression is the distance between the viewpoint and the reference point.
[0060]
[Expression 7]

If A = − (X1−Xf) * r / (r−Z) and B = (Y1−Yf) * r / (r−Z), then equation (B-4) can be rewritten as follows.
[0061]
[Equation 8]
x1 (θ) = A * sinθ + B * cosθ (B-6)
As shown in FIG. 8, a case is considered in which the direction of the vehicle is inclined by an angle β with respect to the direction of the lane. In this case, the x coordinate of the point p1 can be obtained by replacing the θ component of the music coordinates of the formula (B-6) with θ + β. That is, the x coordinate of the point p1 corresponding to the angle β is obtained by the following equation (B-7).
[0062]
[Equation 9]
x1 (θ + β) = A * sin (θ + β) + B * cos (θ + β) (B-7)
On the other hand, the y component of the point p1 is considered as follows. Since it is necessary to update the display at a high speed when the vehicle is traveling at a certain high speed, the range that β can take is considered to be relatively narrow. Also, the elevation angle φ from the horizon is considered to be a relatively small value. Under this assumption, when θ in the above equation (B-5) is replaced with θ + β and further equation modification is performed, the following is obtained.
[0063]
[Expression 10]

Here, since both sinφ and sinβ are small, if sinφ * sinβ≈0 and further cosβ≈1, the result of the following equation (B-9) is obtained.
[0064]
[Expression 11]
y1 (θ + β) ≈y1 (θ) (B-9)
From the equation (B-9), even when the traveling direction of the vehicle deviates from the lane direction, it is not necessary to correct the y coordinate of the point on the white line. Even if the y coordinate of the reference data is used as it is, the shape of the displayed white line and the actual white line are close to each other and look the same for the driver.
[0065]
In order to perform the above processing smoothly, the driving viewpoint runway shape storage unit 24 stores point data (A, B, y) constituting a white line. That is, one point is associated with a set of point data (A, B, y) on the white line visible from there. A and B are coefficients of the formula (B-7), and y is a y-axis coordinate on the projection plane.
[0066]
In the navigation control unit 10, the inclination angle β in the vehicle direction is obtained from the detection signal of the gyro sensor. At this time, the two-dimensional map data is referred to. By applying the inclination angle β and the stored coefficients A and B to the equation (B-7), x (θ + β) is obtained. Further, the y coordinate is used without modification regardless of the magnitude of the inclination. After obtaining all the drawing points (x (θ + β), y), the drawing points are connected to obtain a corrected white line image.
[0067]
"Correction for both lateral shift and tilt"
During actual travel, both lateral displacement of the vehicle with respect to the lane and inclination in the vehicle direction occur simultaneously. Therefore, it is preferable to perform both of the two processes of lateral deviation correction and inclination correction. Specifically, first, as the reference data, the white line shape when the vehicle is facing the lane direction at the center of the lane is read out. And the correction | amendment with respect to the inclination of a vehicle direction is performed, and the correction | amendment with respect to a lateral shift is then performed. As a result, a white line shape that matches the actual situation is obtained.
[0068]
The white line shape correction processing has been described above. Here, the case of a straight road has been mainly described, but the white line shape can be corrected by coordinate conversion even when the road and the white line are curved. That is, a process for converting the position and direction of the viewpoint may be performed based on the lateral deviation detection value and the inclination detection value.
[0069]
According to the present embodiment, it is possible to present to the driver a running road shape that matches the actual situation when the vehicle is in any position in the lateral direction with respect to the lane. That is, the vehicle does not travel at a fixed position on the road, but the travel position shifts in the lateral direction, and the viewpoint position shifts accordingly. However, even if the viewpoint corresponding to the stored track shape is different from the actual viewpoint, the track shape viewed from the actual viewpoint can be displayed by the above conversion process.
[0070]
In addition, according to the present embodiment, it is possible to present the driver with a runway shape that matches the actual situation regardless of the angle between the vehicle direction and the lane direction. That is, the traveling direction of the vehicle does not necessarily coincide with the direction of the road, and the traveling direction assumed in the stored traveling road shape may deviate from the actual traveling direction. Even in such a case, the running road shape in front of the vehicle in accordance with the actual situation can be displayed by the above correction process.
[0071]
Further, by correcting both the lateral deviation and the inclination, a more appropriate runway shape can be displayed.
[0072]
Further, the above correction processing also contributes to the reduction of the data amount in that an appropriate white line shape can be presented without preparing other types of white line shape data for the same point.
[0073]
In addition, in the present embodiment, the drawing point data (A, B, y) is stored for correcting the vehicle direction. However, if only the lateral shift correction is performed, the drawing point data (x, y) is simply stored. It only has to be memorized.
[0074]
"White line display by vehicle type"
As described above, in the present embodiment, the white line shape viewed from the viewpoint of the driver in association with each point on the road is stored in advance. The process of storing the white line shape in advance is preferably performed as follows, for example.
[0075]
Prepare white line data (original data) when the road is viewed from directly above. The original data is data that becomes the material of the coordinate conversion processing of FIG. 3 described above, and is stored in the map database storage unit 20 of FIG. The original data is read by the navigation control unit 10. The navigation control unit 10 sets the viewpoint and the reference point, performs the coordinate conversion process of FIG. 3, and obtains the white line shape viewed from the desired viewpoint. As described above, a white line shape is obtained for each point on the map. The obtained white line shape data is stored in the storage device, and constitutes the driving viewpoint runway shape storage unit 24 of FIG. In addition, a readable / writable storage device such as a hard disk is provided as a part or all of the map database storage unit 20 so that the white line shape can be stored. The navigation control unit 10 reads and processes the white line shape from a hard disk or the like when displaying the running road shape on the display.
[0076]
By the way, the shape of the white line that can be actually seen varies greatly depending on the vehicle type. This is because the angle at which the road surface can be seen, the position of the viewpoint, the elevation angle, and the like vary greatly depending on the vehicle type. For example, the viewpoint of an RV vehicle is significantly higher than that of a sports car. Therefore, it is preferable to change the shape of the white line in accordance with the vehicle type, thereby making it possible to match the white line to be displayed with the actually visible white line.
[0077]
Referring to FIG. 9, the high-precision map database has original data indicating a white line shape viewed from directly above. The navigation control unit 10 obtains information on the height of the driver's viewpoint from the outside. For example, vehicle type information, vehicle height information, or information on the height of the viewpoint itself is input. This information may be input from an in-vehicle device or the like, or may be input by a user using an input device. The user may select a desired viewpoint height. Based on the input information, a white line shape corresponding to the viewpoint height of the vehicle and an appropriate projection plane is created. Thereby, a map database corresponding to the vehicle type is created.
[0078]
A modification of the above process will be described. The high-precision map database in FIG. 9 may have a white line shape (for each point) viewed from the height of the reference viewpoint. That is, one white line shape database based on an appropriate viewpoint is prepared in advance. The navigation control unit 10 converts the standard white line shape data based on the input viewpoint height information, and generates a white line shape corresponding to the viewpoint height (and reference point) of the vehicle. Coordinate conversion processing for changing the height of the viewpoint from the reference viewpoint height to the viewpoint height of the corresponding vehicle may be performed.
[0079]
"White line shape data generation timing"
It is considered that the processing for generating and storing the white line shape as viewed from the driving viewpoint in advance is preferably performed at any of the following three timings.
[0080]
(1) Set parameters for each vehicle (designation of viewpoints and reference points), convert all data at once, and store the converted data. This aspect has the advantage that the vehicle-specific data can be used immediately at any time.
[0081]
(2) When the route to the destination is calculated, the white line shape data of the point on the route is converted. Since there is a possibility that the vehicle deviates from the route and travels to another road, it is preferable to complete the white line shape conversion process not only for the guidance route but also for other surrounding routes at the branch point. For example, the white line shape data in the three directions of the next intersection is corrected in advance so as to match the vehicle type.
[0082]
(3) The driving viewpoint white line shape corresponding to the point data around the vehicle position is always subjected to conversion processing for vehicle type adaptation. As the vehicle moves, the previous conversion data is discarded, and the conversion process of the white line shape of the new approaching point is performed. According to this aspect, the white line shape can be displayed efficiently and quickly even when the route guidance is not being performed.
[0083]
When the above (2) is adopted, it may be possible to present the runway shape only during route guidance. In (3), the calculation processing load of the control unit 10 increases. Therefore, it is considered most preferable to perform the process (1).
[0084]
"Map database recording medium"
The present invention may be applied to modes other than the above-described runway shape display device. For example, the present invention may be realized in the form of a recording medium that records a map database. The map data described in relation to the driving viewpoint runway shape storage unit 24 of FIG. 1 is recorded on the recording medium. The recording medium may be one that can read and write data by any method such as magnetism, electricity, and light. For example, CD-ROM and DVD are suitable. The map database may be stored in a recording medium together with other navigation-related programs. Furthermore, the present invention may be applied to other aspects, such as method aspects.
[0085]
【The invention's effect】
As described above, according to the present invention, it is possible to present the running road shape viewed from the viewpoint of the driver reliably and quickly without being affected by environmental conditions.
[Brief description of the drawings]
FIG. 1 is a block diagram showing a configuration of a navigation device provided with a runway shape display device of the present invention.
2 is a diagram showing track shape information stored in a driving viewpoint track shape storage unit in FIG. 1; FIG.
FIG. 3 is a diagram showing a process for creating in advance the road shape information of FIG. 2;
4 is a diagram showing a method for reducing the amount of white line shape data stored in the driving viewpoint running path shape storage unit of FIG. 1; FIG.
FIG. 5 is a diagram illustrating processing for correcting a white line shape with respect to a lateral shift of a vehicle with respect to a lane.
FIG. 6 is a diagram illustrating a process of correcting a white line shape with respect to the inclination of the vehicle direction with respect to the lane direction.
FIG. 7 is a diagram illustrating a process of correcting a white line shape with respect to the inclination of the vehicle direction with respect to the lane direction.
FIG. 8 is a diagram illustrating a process of correcting a white line shape with respect to the inclination of the vehicle direction with respect to the lane direction.
FIG. 9 is a diagram illustrating white line data generation processing adapted to the viewpoint height of each vehicle type.
[Explanation of symbols]
10 navigation control unit, 12 GPS device, 14 gyro sensor, 16 vehicle speed sensor, 18 position detection unit, 20 map database storage unit, 22 two-dimensional map storage unit, 24 driving viewpoint runway shape storage unit, 30 input device, 32 display, 34 Speaker, 36 Head-up display.

Claims (7)

Each of a plurality of points on the road on the map and a road shape storage means for storing in association with a driving viewpoint road shape representing a front road shape seen from the viewpoint of the vehicle driver at each point,
Own vehicle position detecting means for detecting the own vehicle position;
Display means for displaying the driving viewpoint runway shape;
A display processing means for reading out the driving viewpoint running road shape corresponding to the own vehicle position detected by the own vehicle position detecting means from the running road shape storage means and displaying the driving means on the display means;
Lateral deviation detecting means for detecting lateral deviation of the vehicle with respect to the runway;
Including
In the display processing means, based on the lateral deviation, the driving viewpoint running road shape read from the running road shape storage means is coordinate-converted to a running road shape seen from the laterally shifted viewpoint.
A runway shape display device characterized by that. In the runway shape display device according to claim 1,
The runway shape storage means stores a discrete representative point set extracted from the runway shape when looking forward from the viewpoint of the driver at the corresponding position as the driving viewpoint runway shape at each position,
The display processing means includes a means for generating a continuous road shape based on the discrete representative point set. In the runway shape display device according to claim 1 ,
The display processing means selects a driving viewpoint runway shape to be read from the storage means on the basis of a runway around the vehicle position or a scheduled travel path. In the runway shape display device according to claim 1,
Including an inclination detection means for detecting the inclination of the vehicle direction with respect to the running direction,
In the display processing means, a driving road shape display device read from the road shape storage means is coordinate-converted into a driving road shape seen from an inclined viewpoint based on the inclination. . In the runway shape display device according to claim 1,
The display means is a head-up display that displays an image on a windshield of a vehicle. In the runway shape display device according to claim 1,
The driving viewpoint runway shape is data indicating the shape of a line representing a lane drawn on the runway, and the runway shape display device. A map database recording medium used by the road shape display device according to claim 1,
A map database of roads is recorded, and in the map database, each of a plurality of points on the road is associated with a driving viewpoint runway shape representing a roadway shape ahead viewed from the viewpoint of the vehicle driver at each point. A map database recording medium characterized by that.

Images