Method of displaying navigation data for a vehicle in an image of the vehicle environment, a navigation system for performing the method, and a vehicle comprising a navigation system

Abstract: From navigation data of a vehicle there is formed an indication signal which is superposed on an image of the local environment which is generated by an image pick-up unit. The combination is displayed on a display unit.

Description: Method of displaying navigational guidance information for a vehicle in an image of the vehicle environment, a navigational system for performing the method, and a vehicle comprising a navigation system. The invention relates to a method for displaying navigational guidance information provided by a navigation system for a vehicle, said information being superposed on a scenic image associated with a vehicle position. JP-A-62-93614 describes a running guidance apparatus for vehicle: A map, the actual images of a plurality of predetermined points on said map and information necessary for running guidance such as a plurality of direction indicating marks are preliminarily stored in a memory means like a compact disk. A running route from the present area to an objective area is set to a control circuit on the basis of the present point information from a present position recognizing apparatus and the destination area information from a destination area indicating means. Then, the present area information is collated with the stored informations and, when it is detected that the vehicle has approached one of the predetermined points, the image of the predetermined point and the direction indicating mark are displayed on a display device in a superposed state on the basis of the set running route. The present invention recognises the need for superposing the navigational guidance information on a scenic image that is true to life and not subaltern to the navigation system, for so keeping a user person in close contact with reality. Amongst other things, it is an object of the present invention to provide a method of displaying navigation an guidance information for a vehicle in an image of the local vehicle environment which allows for a simple, user friendly and readily interpretable display of the navigation data. The invention is characterized in that said image is real-time and independent from said information procurement system as being generated instantaneously and continually by a video or television camera that is physically joined to the vehicle. BRIEF DESCRIPTION OF THE FIGURES Fig. 1 shows a flowchart of a method in accordance with the invention; Fig. 2 diagrammatically shows the structure of a navigation system suitable for performing the method in accordance with the invention; Fig. 3 shows examples of a local image for display on a display unit in combination with navigation data; Fig. 4 illustrates the data structure used; Fig. 5 illustrates the sorting of the connections; Fig. 6 illustrates the conversion into polygons. DESCRIPTION OF THE FIGURES Fig. 1 shows a flowchart of a method in accordance with the invention. In block 11 an image of the environment is generated by means of an image pick-up unit, for example a video camera aboard a vehicle. In block 12, known from the article "CARIN, a car information and navigation system" by M.L.G. Thoone, Philips Technical Review, Vol. 43, No. 11/12, pp. 317-329, December 1987, the navigation data to be displayed therein are generated; in block 13 an indication signal is formed therefrom, for example by means of a known video generator, which indication signal is superposed in block 14, for example by means of a video combination module, on the environment image. In block 15 the combination is displayed on a display unit, for example a video display, a television receiver or a monitor, aboard the vehicle. Fig. 2 diagrammatically shows the structure of a navigation system suitable for performing the method in accordance with the invention. Module 21 is a known car navigation system, for example a CARIN system as described in the cited article by M.L.G. Thoone, which supplies navigation data on the basis of measurement data from sensors (such as a compass and wheel sensors which measure the number of revolutions) and topographic data in a data structure, for example coordinates which represent the current position of the vehicle and coordinates which represent a calculated optimum route to be followed. In module 22 this navigation data is subjected to a transformation in accordance with the position of the image pick-up unit 24 with respect to the environment: the relevant area of the data structure containing the topographic data is "viewed" from the point of view of the image pick-up unit as described in the previously filed, non-prepublished Netherlands Patent Application No. 8900056 (= PHN 12.810). Navigation data to be displayed, for example indications of the route to be followed, thus correspond to the roads in the local image of the environment. Module 23 is a video generator which forms an indication signal from the transformed navigation data: for example, a stylistic indication of the route to be followed. Image pick-up unit 24 (a video camera or television camera) supplies an image of the environment. In a combination module 25 the indication signal and the environment image are combined so as to form a combined signal which is displayed on display unit 26 (a video display, television receiver or monitor). Fig. 3 shows an example of a display of an image of the environment in combination with stylized navigation data. The arrow indicates the direction to be followed as calculated by the navigation system: in this case indication to turn left, which indication is overlaid on the road section to be followed. When the navigation data is displayed in a distinct manner, for example in a flashing or boxed manner, or in a bright colour which is distinct from the remainder of the image, the user will see how to act at one glance. In the CARIN data base roads are represented by the coordinates of their centre lines. For a realistic display on a display unit, it is important to convert this representation into a representation by way of polygons which is compatible with the realistic image of the environment. To this end, the structure in the CARIN data base is converted into a new structure whose most important categories are: nodes (P), each of which is represented by two coordinates (or three coordinates if the data base also contains information as regards altitude); roads (R), each of which is represented by the number and location of the constituent nodes; links (L), each of which is represented by the associated road and its direction; intersections (I), each of which is represented by the number and the location of the constituent links. The category of links is extended to p-links (PL) by including also the left-hand and the right-hand side of the road; the list of roads and nodes is thus increased (the left-hand and the right-hand side of the road also constitute a separate road defined by nodes), but the structure remains the same, see Fig. 4. Subsequently, for each intersection the links leading thereto are sorted in a counterclock-wise fashion. This is realised as follows: the first link L0 referred to acts as a reference. If the angle between this link L0 and the next link L1 is greater than the angle between L0 and the subsequent link L2, L1 and L2 are interchanged in the list of links, see Fig. 5. The cosine and the sine of the angle a0 enclosed by the link L0 with respect to the positive X-axis are: cos(a0) = (x0B - x0A) / SQRT ((x0B - x0A) 2 + (y0B - y0A) 2 ); sin(a0) = (y0B - y0A) / SQRT ((x0B - x0A) 2 + (y0B - y0A) 2 ); and the same is applicable to the links L1 and L2. It follows therefrom that cos(a10) = cos(a1 - a0) = cos(a1) * cos(a0) + sin(a1) * sin(a0); sin(a10) = sin(a1 - a0) = sin(a1) * cos(a0) - cos(a1) * sin(a0); and the same is applicable to cos(a20) and sin(a20). The sequence is then determined as follows: if sin(a10) > 0 subsequently if sin(a20) > 0 subsequently if cos(a10) > cos(a20) do not interchange, and otherwise interchange otherwise do not interchange otherwise if sin(a20) > 0 interchange otherwise if cos(a10) < cos(a20) do not interchange otherwise interchange. Subsequently, for each intersection the centre line of all links departing from the respective intersection is converted into a polygon, see Fig. 6. For all points, except for the terminal points, the point of intersection of adjoining left-hand and right-hand road sides is calculated. The vector having the length D1, perpendicular to PQ, is given by: (xpq,ypq), where xpq = - (yq - yp) * gpq and ypq = (xq - xp) * gpq, where gpq = D1 / SQRT((xq - xp) 2 + (yq - yp) 2 ). To the vector perpencidular to QR, having the length D2, an analogous expression is applicable: (xqr,yqr), where xqr = - (yr - yq) * gqr and yqr = (xr - xq) * gqr, where gqr = D2 / SQRT((xr - xq) 2 + (yr - yq) 2 ). The point of intersection (xs,ys) searched is the point of intersection of the line between (xp+xpg,yp+ypg) and (xq+xpq,yq+ypq) and the line between (xq+xqr, yq+yqr) and (xr+xqr, yr+yqr). The following is applicable: xs = xpq + n * xp + (1 - n) * xq and ys = ypq + n * yp + (1 - n) * yq ; xs = xqr + m * xq + (1 - m) * xr and ys = yqr + m * yq + (1 - m) * yr ; solution of these equations for the parameter n results in: n = [ (yq - yr) * (xpq + xq - xqr - xr) - (xq - xr) * (ypq + yq - yqr - yr) ] / ... ... / [(xq - xr) * (yp - yq) - (yq - yr) * (xp - xq) ] If the denominator is zero, the two line segments are situated one in the prolongation of the other and the parameter n is assumed to equal zero. The point of intersection (xs,ys) has thus been found. Each centre line has thus been supplemented so as to form a real street having a given width. Finally, all polygons thus found are coupled to the associated intersections. Because the links have been sorted while proceeding counterclock-wise, each time the point of intersection of the left-hand edge of a link with the right-hand edge of the next link is calculated. The calculations are fully analogous to the foregoing. The network of roads consisting of "dashed roads" has thus been converted into a network of "real" roads. The navigation data can now be positioned so as to correspond better to the image of the environment.

Claims: A method for displaying navigational guidance information provided by a navigation system (12,13) for a vehicle, said information being superposed (14) on a scenic image associated with a vehicle position, characterized in that said image is real-time and independent from said navigation system (12, 13) as being generated (11) instantaneously and continually by a video or television camera (24) that is physically joined to the vehicle. A method as claimed in Claim 1, where the navigational guidance information is generated by the navigation system on the basis of measurement data from sensors and/or topographic data from a data structure, characterized in that prior to the superposing, the navigational guidance information is transformed in conformity with a position of the video or television camera with respect to the environment. A method as claimed in Claim 2, characterized in that the navigational guidance information is transformed by way of a perspective transformation. A method as claimed in any one of the Claims I to 3, characterized in that the navigational guidance information is displayed in a manner distinct from the remainder of the image. A method as claimed in any one of the Claims 1 to 4, where the navigational guidance information is generated by the navigation system on the basis of measurement data from sensors and topographic data from a data structure in which roads are represented by co-ordinates of their centre lines, characterized in that prior to the superposing of the navigational guidance information, the representation of the roads is converted into a representation by polygons. A navigation system arranged for executing a method as claimed in any of Claims 1 to 5, comprising an information procurement system for providing navigational guidance information (21), a scenic image providing system for providing a scenic image associated with a particular vehicle position and display superposition (25) means fed in parallel by said information procurement system, and by said scenic image providing system, characterized in that said scenic image providing system is arranged for operating real-time and independently of said information procurement system by comprising a video or television camera (11, 24) that is physically joined to the vehicle for instantaneously and continuously producing said scenic image, a transformation module (22) for transforming the navigational guidance information produced by the information procurement system, a video generator (24) for generating an indication signal from the transformed navigational guidance information, a combination unit (25) for combining the scenic image with the video transformed indication signal, and a display (26) unit for displaying the combined signals.

Inventors: DE JONG DURK JAN, DE JONG, DURK JAN
Applicants: KONINKL PHILIPS ELECTRONICS NV, KONINKLIJKE PHILIPS ELECTRONICS N.V.
Application year: 1990
Main classification: G01C21
IPC codes: G01C21, F02D45, G09G5, G08G1, B60R16