WO2015091167A1

WO2015091167A1 - A method and device for displaying traffic data

Info

Publication number: WO2015091167A1
Application number: PCT/EP2014/077272
Authority: WO
Inventors: Simon BOX; Xiaoyu Chen; Benedict WATERSON
Original assignee: Siemens Plc
Priority date: 2013-12-17
Filing date: 2014-12-10
Publication date: 2015-06-25
Also published as: GB2521366A; GB201322312D0

Abstract

A method of visually representing traffic flow parameters comprises selecting an area of interest on a map (50), defining cells (51) within the area of interest and extracting data (52) relating to a traffic flow parameter for each cell. A three dimensional representation (26 to 31) of a first traffic flow parameter is applied (54) to the map in the cells in the area of interest and the map is displayed with the three dimensional representation of the traffic flow parameter. The method further comprises extracting data relating to a further traffic flow parameter for each cell; applying to the map in the area of interest an alternative representation of the further traffic flow parameter; and displaying the map with the alternative representation and the three dimensional representation. The alternative representation comprises rendering the degree of transparency to be proportional to the parameter being displayed.

Description

A METHOD AND DEVICE FOR DISPLAYING TRAFFIC DATA

This invention relates to a method and apparatus for visually representing traffic flow parameters.

The application is of particular benefit for representing vehicle traffic in urban areas, but may also be used for representing other types of traffic, such as trains, trams, shipping, pedestrians or cyclists.

Visual representation of traffic flows is well known, for example from Google® traffic data where specific colours give an indication of levels of traffic congestion with green indicating free- flowing traffic, yellow, some congestion and red, congested.

Grey is used where insufficient data is available. A road map with the colour displayed on it allows users to see how much traffic there is on their intended route.

However, in an intelligent transportation system of this type, it can be difficult to provide a sufficiently clear display, to operators and members of the public, of data about road conditions purely using colour. The number of levels of fine detail is limited by the difficulty in discerning distinctions between colours. This is even more of an issue if the users or operators are colour-blind.

In accordance with a first aspect of the present invention, a method of visually representing traffic flow parameters comprises selecting an area of interest on a map; defining cells within the area of interest; extracting data relating to a traffic flow parameter for each cell; applying to the map in the cells in the area of interest a three dimensional representation of the traffic flow parameter; and displaying the map with a three dimensional representation of the traffic flow parameter, wherein the method further comprises extracting data relating to a further traffic flow parameter for each cell; applying to the map in the area of interest an alternative representation of the further traffic flow parameter; and displaying the map with the alternative

representation and the three dimensional representation; wherein the alternative representation comprises rendering the degree of transparency to be proportional to the parameter being displayed.

The present invention overcomes the limitations of using colour as the mechanism by which traffic flow parameters are displayed by using a three

dimensional representation making height proportional to the parameter being displayed. Preferably, the three dimensional representation comprises rendering the height of the cell on the display to be proportional to the parameter being displayed.

In one embodiment, an increase in a traffic flow parameter is represented by an increase in height.

Alternatively, an increase in a traffic flow parameter is represented by a decrease in transparency.

Preferably, the method further comprises manipulating the displayed visual representation by pan or zoom.

Preferably, the traffic flow parameter comprises one of number of vehicles, or traffic speed.

Preferably, the further traffic flow parameter comprises the other of number of vehicles, or traffic speed.

In accordance with a second aspect of the present invention, a device for visually representing traffic flow information comprises a communication unit for receiving one or more traffic flow parameters; a source of mapping information; and a display; wherein the device is adapted to display a traffic flow parameter in a three dimensional representation overlaid on an area of interest on a map derived from the source of mapping information and to display a further traffic flow parameter rendered by the degree of transparency being proportional to the parameter being displayed.

An example of a method of visually representing traffic flow parameters and an associated device will now be described with reference to the accompanying drawings in which:

Figure 1 illustrates an example of the format of a conventional traffic data displayed on a map;

Figure 2 illustrates a first example of an enhanced display using a visualisation method according to the present invention;

Figure 3 illustrates the display of Fig.2 in combination with a conventional display format;

Figure 4 illustrates an alternative display format which may be used with the display of Fig.2;

Figure 5 is a block diagram of a device for carrying out a visualisation method according to the present invention; Figure 6 is a flow diagram illustrating an example of a method according to the present invention.

As described above, conventional traffic information systems use red, yellow and green lines on a map to indicate how busy a particular section of road is. Figure 1 illustrates this, using three shades of grey. The thresholds for insufficient data, low level, medium level and high level, at which the colours change in the system can be adapted according to the operator's requirements, but if the operator is to be able to interpret the data effectively, then the data cannot be displayed with more than the low, medium and high levels of detail. In the example shown, sections 1 to 4 represent areas of high congestion, sections 5 to 9 represent areas of medium congestion and sections 10 to 15 represent areas of low congestion. However, this 2-dimensional representation does not give an operator any fine detail. In order to get more information, such as a more accurate idea of the number of vehicles, or average speed, an alternative representation is required.

Figure 2 illustrates a first embodiment of the present invention. Areas of interest for traffic state estimation are typically broken down into cells with certain parameters attached to those cells. The parameters may be measurable phenomena, such as number of vehicles present within the cell, or average speed of the vehicles present within the cell, or derived parameters such as traffic flow and traffic density. Equally, the parameters may be abstract concepts such as "weight" of traffic, or deviation from normal conditions. In Fig.2, the area of interest on the map is broken down into cells for which traffic data can be obtained. The size of the cells determines the granularity at which data are presented. For example at fine granularities cells may be one lane in width, at coarser granularities cells may cover two or more lanes.

In the example of Fig.2, instead of allocating a colour to an area based on whether or not it exceeds one of four levels and then the display being a map showing different colours to indicate having achieved one of the different levels of the traffic information parameter at the particular point on the map, the display indicates different levels of the parameter by means of height. Height allows the user to discriminate between many different levels quite easily and the display could even be continuous. This type of display presents more fine detail than a colour based display and also is suitable even if the users or operators are colour-blind. Thus, the section 1 which previously represented high congestion can be broken down into heights indicating the number of vehicles in the cell and a scale superimposed if necessary, so that the number can be determined at a glance. For this example, section 1 simply showed that there was a high level of congestion, whereas the display of the present invention has two different heights in the same distance with section 31 showing there are 20 vehicles in the cell and section 30, shows 15 vehicles in the cell. Further back from that junction, section 5 indicated a medium amount of congestion, whereas the invention shows that there are 10 vehicles in the first cell 29, 5 in the next two cells 27, 28 and 2 in the final cell 26 of that section. In another part of the map, similar detail can be discerned from cells 20 to 25. Cells 20 to 22 show the number of vehicles dipping from 3 to 1 , then increasing again to 2 and continuing upwards towards the next junction. This dip does not show in the conventional colour representation. Cells 23 and 24 contain the same number of vehicles, but with a simple colour representation, this would not have been apparent as their combination with adjacent data resulted in them being on opposite sides of threshold of medium to high.

Figure 3 illustrates how the invention is further improved by means of a combination of transparency and height above the map, allowing two different traffic parameters to be displayed simultaneously in a format which is easily distinguishable for the operator. For example, if the height above the map indicates the number of vehicles present in a particular cell, as explained with respect to Fig.2, then the degree of transparency of the height representation for that cell may provide information about the average speed of those vehicles. In this example, as the speed reduces, the degree of transparency reduces, until the height rendered parameter is entirely opaque on the display.

As well as using the display method of the present invention, as described with respect to Figs.2 and 3, this may be combined with conventional colour indications as shown in the example of Fig.4. In this embodiment the indication of number of vehicles in a cell is illustrated by the 3-D display using height, but is combined with an indication of the effect of this number of vehicles per cell on the particular road, displayed using conventional 2-D colour coding to show a level of congestion.

It would even be possible to display three different parameters by combining the example of Fig.3 with the conventional 2-D colour coding. The embodiments illustrated above have been described on the basis of using a 2-D road map and superimposing displays on this to provide additional data relating to the route, but the information may equally well be displayed on any map based visualisation, for example overlaid on GIS terrain maps.

The present invention uses three dimensional height and transparency in combination to provide additional information which is not possible using just colour and assists an operator or members of the public in interpreting a greater variety of data without making the display overly complex.

In the present invention one parameter is associated with the height aspect and further parameters are indicated simultaneously using transparency and optionally, also colour. For example, the colour aspect may display normal traffic in a known colour e.g. green and increasing degrees of abnormality captured by a series of colours, typically moving from green, through amber or yellow to red. For the height aspect, the apparent height above ground level shown on the display indicates an increasing value, for instance an increase in speed may be shown by an increase in height, or a higher number of vehicles in a cell may be shown by a greater height. In combination with the colour coding e.g. if colour normality, height is number of vehicles and transparency is average speed, the display can provide a good illustration of where problems are building up, such as increase in queuing in one lane of a set of traffic lights, or bunching behaviour e.g. where cells alternate between low height, green and greater height, red along an arterial route. Clearly, the specific parameters used in the examples do not have to be displayed in the way described in that example and height may be used as the means of displaying average speed, for example, rather than number of vehicles.

By using an easy to interpret combination of display mechanisms for multiple parameters, operators are able to perceive problem areas more quickly than with a conventional colour only visualisation. For instance if count is processed to indicate normal flow, and two degrees of abnormal flow indicated by the use of red, amber and green colours and speed is associated with height then the operator can look for abnormal changes in flows, indicated by amber or red colours, and this will be confirmed by appropriate changes in the speed indication, speed reducing where abnormally high flow is present. If speed continues to be normal and the flow is unusual then this potentially indicates a problem elsewhere in the traffic network. The operator can also look for a road on which the speed indication changes abruptly. This area can then be more closely examined to determine whether there is a problem in the area.

In the embodiments described, height has been displayed in a series of bands, rather than contiguous values. This allows normal values to be indicated by a low height and abnormal values to be indicated by increasing height. This makes it easier for an operator to spot abnormal conditions directly through height above the ground. However, a continuous display could be used.

Sources of data for traffic state estimation include buried roadside sensors, CCTV, automatic number plate recognition cameras, microwave detectors and wireless data sources, such as smart phones or blue tooth detectors. The method for visually representing traffic flow parameters according to the present invention may be used to display traffic flow data which has been obtained and processed in various ways. For example, the traffic flow data may have been derived using a traffic state estimation methodology as described in our co-pending application, WO2013/110815.

The present invention enables multiple parameters to be displayed to an operator using different display mechanisms to represent the different parameters. As well as, or instead of, conventional two dimensional representation of traffic congestion using colour applied to roads on a map, more detail is provided about the conditions of the traffic in those lanes using a three dimensional representation overlaid on the area of interest and levels of transparency. In either a combined visualisation comprising a map with two and three dimensional overlays, or a map with the traffic flow parameters rendered as height, the display is designed so that the operator can manipulate the image, e.g. by use of zoom and pan, to enable the area of interest to be seen from different angles and distances.

Figure 5 is a block diagram of a device for carrying out the method of the present invention. The device 49 comprises a communications unit 43, a processor 45 and a display 46. In use, a source of mapping data 44 and sources of traffic data 40, 41, 42 are connected to the device. If the mapping data is stored locally, it may be retrieved directly by the processor 45 via link 48 from a store, but if the mapping data is from an external source, it is received via the communications unit 43 over link 47.

The operation of the device will now be described in more detail, with particular reference to the example illustrated in Fig.6. The operator chooses an area of interest for which he requires traffic information. Mapping information may be stored locally in a map source 44 on the device 49, in which case it can be extracted 50 directly by the processor 45 via link 48, or else the mapping information may be acquired via link 47 from a remote source 44, received through the communications unit 43. The map of the area of interest is divided up into cells 1 and data from the one or more sources 40, 41, 42 of traffic data is received 52 in the communications unit 43 of the traffic flow information device 49 for each cell. A parameter is chosen 53 for display, either entered by the operator, or chosen from a standard list of parameters and the processor 45 converts the traffic data from one source 20 into a 3-dimensional representation, rendering the height of the cell on the display to be proportional to the parameter being displayed. A check 55 is made to determine a further parameter to be displayed, for example if the standard list includes pairs of parameters, this happens automatically, or if the operator has only chosen the first parameter, then a second one is chosen before that further parameter is displayed 56 in an alternative format. The alternative format comprises a change to the transparency of the traffic information that has been displayed as a 3 dimensional representation. In addition, the display may include a 2-dimensional colour based representation of a further parameter. The combined traffic parameters and mapping information are output 57 to the display 46. The display is preferably interactive allowing the operator to manipulate 58 the displayed image in order to see it from different perspectives, or to zoom in on areas of concern. The traffic information 20, 21, 22 may be updated at regular intervals and so the display refreshes regularly 59.

Claims

1. A method of visually representing traffic flow parameters, the method comprising selecting an area of interest on a map; defining cells within the area of interest; extracting data relating to a traffic flow parameter for each cell; applying to the map in the cells in the area of interest a three dimensional representation of the traffic flow parameter; and displaying the map with a three dimensional representation of the traffic flow parameter; wherein the method further comprises extracting data relating to a further traffic flow parameter for each cell; applying to the map in the area of interest an alternative representation of the further traffic flow parameter; and displaying the map with the alternative representation and the three dimensional representation; . wherein the alternative representation comprises rendering the degree of transparency to be proportional to the parameter being displayed.

2. A method according to claim 1 , wherein the three dimensional representation comprises rendering the height of the cell on the display to be proportional to the parameter being displayed.

3. A method according to claim 2, wherein an increase in a traffic flow parameter is represented by an increase in height.

4. A method according to any of claims 1 to 3, wherein an increase in a traffic flow parameter is represented by a decrease in transparency.

5. A method according to any preceding claim, wherein the method further comprises manipulating the displayed visual representation by pan or zoom.

6. A method according to any preceding claim, wherein the traffic flow parameter comprises one of number of vehicles, or traffic speed.

7. A method according to claim 6, wherein the further traffic flow parameter comprises the other of number of vehicles, or traffic speed.

8. A device for visually representing traffic flow information, the device comprising a communication unit for receiving one or more traffic flow parameters; a source of mapping information; and a display; wherein the device is adapted to display a traffic flow parameter in a three dimensional representation overlaid on an area of interest on a map derived from the source of mapping information and to display a further traffic flow parameter rendered by the degree of transparency being proportional to the parameter being displayed .