DE10303046A1 - Quantitative estimation of visibility in motor vehicle, by using e.g. measurement of sharpness or contrast of image obtained from intensity differences of adjacent pixels - Google Patents

Abstract

Image data are detected from the surroundings. At least one region of a detected image is evaluated to form a characteristic measurement value. A visibility is determined using a reference relating the measurement value to a visibility. A measurement value for the sharpness or contrast of the image may be used, and obtained from the differences of intensities of adjacent or neighboring pixels. Independent claims are included for the following; (1) an apparatus for estimating visibility; (2) a system for acquiring references.

Description

The The invention relates to a method and a device for quantitative appraisal visibility in vehicles and a system for recording reference values for a such method or device.

From the DE 101 04 734 A1 and the EP 0 687 594 B1 are known methods for detecting fog or smoke or for the qualitative assessment of the weather situation, based on which technical equipment of the vehicle, such as fog lights or vehicle headlights, are controlled.

Out The VDI Guidelines VDI 3786 are devices and methods for stationary Determination of the visibility by means of a transmission measurement known. Such devices are along the highway A8 in Nebelgefährdeten Arranged sections. They determine the visibility and from it will be the maximum allowable Speed set by means of a traffic control system. at These devices is a light beam from a transmitter in the direction of the receiver a few meters away. This receiver measures the amount of light and closes out of sight. These devices are for stationary use only suitable because air turbulence in the area of a moving Object can lead to errors in visibility.

Out International patent application WO 02/06851 A1 is a method for visibility determination, in which an object in different Measuring positions and thus distances observed by the meter is and based on the contrast of the object to be measured in the both distances based on an exponential relationship the visibility is closed. This procedure is very complicated and requires the observation of a single object of measurement for a long time and over different measuring positions.

From the EP 1 067 399 A2 a method for visibility determination is known, in which from the detected by a video sensor image data in conjunction with the determined by means of a radar or Lidarsensors distance to an object the visibility is determined. This method requires very expensive, costly sensors.

From the DE 100 58 633 A1 is also known a method for visibility determination, is closed by the turbidity on the visibility. Similar to the VDI guideline - VDI 3786 - an exponential approach for the determination of the attenuation coefficients, also known as the transmission coefficient, is used and from this the visibility is estimated. In this method, far-fetched decoys are generated in a complex manner and used for visibility determination.

Of the Invention is based on the object, a method and an apparatus for quantitative estimation the visibility for Specify vehicles that provide a reliable estimate of the visibility for mobile Vehicles allow. These should also be the possibility create a definition of the VDI Guidelines VDI 3786 corresponding to Visibility-compliant visibility indication to provide. Furthermore the invention has the object, a system for the determination of Specify reference values that allow a visual range estimate, which corresponds to the visibility of the VDI guidelines.

This The object is achieved by a method having the features of the claim 1, a device with the features of claim 14 and a system for detecting references with the features of claim 19 solved.

advantageous Embodiments and developments of the invention are the subject the subordinate claims.

The method according to the invention permits the quantitative estimation of the visibility for vehicles, this visibility corresponding to the term or meaning of the visibility defined by the VDI guideline. This is ensured by reference to the reference, which are reference values, typically in the form of a table, in which certain visibility is related to a characteristic measure of the visibility that has been found by the method according to the invention with an evaluation of the detected image or images. This utilization of the correlation makes it possible to obtain a very meaningful, reliable indication of the quantitative estimation of the visibility for vehicles or in vehicles. The range of sight determined by referencing is either provided to the user directly as a range of visibility or as a derived quantity, such as recommended maximum speed, recommended minimum distance, or simply as a warning signal or otherwise. In addition, it is additionally or independently possible to control various vehicle components based on the determined visibility. In particular, components such as windshield wiper control, driving light control, fog light, adaptive cruise control (ACC) or speed limiters (limiters) and similar components have proven to be suitable. By this type of information provided to the vehicle user or the control of vehicle components is a very safe and helpful Ausbil created tion of the invention, which leads to a very relaxed and safe driving the vehicle.

As characteristic measure for at least one The area of a captured image has in particular the sharpness or the contrast or the intensity of the backscattered light of the vehicle represent, proven. These measures can each for itself or in combination with each other or with other characteristic measures a particularly safe and particularly meaningful estimation of the visibility for vehicles deliver.

In addition can the picture to improve the performance of the process in several different areas are divided. This allows besides effective visual assessment provides a reliable distinction from weather conditions such as fog and rain: due the typically inhomogeneous distribution of raindrops on one Vehicle window show the image data from different areas the disc has different characteristics. In a suitable Choice of dimensions of the considered image areas can be achieved, for example be that in one area already one or more drops on the disc are present while another area still completely dry is. Thus, the image data of the affected areas clearly Differences. In contrast, the image data has different Areas of the image for the weather situation "fog" usually similar Characteristics. Thus lets in a simple way by comparing different Areas of an image Rain from fog alone with image processing tools differ. The knowledge of the weather situation he continues to allow a targeted selection of options for determination Relevant characteristic measures or references and thus a weather situation-adapted visibility determination.

As well can be advantageously at different times taken pictures to determine the visibility with weather situation adjustment use. Thus, for example, in the rain, the image data from successive or successively recorded images essential distinguish while this is typically less pronounced or absent in fog. In this case, for example, a sudden change in the image data z. B. a change interpreted as rain within one second or from image to image, while detecting a fog situation with a slow, continuous change the image data goes along.

A Combination of viewing different areas of an image and comparing several recorded at different times Images or image areas allow the further improvement of the inventive method in terms of reliable appraisal the visibility, since individual disturbed Measurements or measures not alone decisive for the visibility estimate are. A combination of viewing different areas of a Picture and the comparison of several taken at different times Images or image areas allow the further improvement of the inventive method in terms of reliable appraisal the visibility, since individual disturbed Measurements or measures not alone decisive for the visibility estimate are.

A advantageous method for comparing the image data provides the determination a measure M for the sharpness or the contrast of the image dar. The calculated from the image data measure M can then easily determine the current visibility be used; In the method, for example, a comparison with predetermined threshold values or value ranges for the measured values or measures done, reducing the reliability of the procedure increased significantly becomes.

there it has proven to be particularly effective M from the differences of the intensities of neighboring or surrounding ones To determine image pixels. For this purpose, the following is advantageously Procedure applied: first be for an image area that may also include the entire image that relative intensity differences determined adjacent pixels. For simplicity's sake the following representation on a row or column of 800 pixels. For the considered 800 pixels are each for neighboring pixels determines the relative intensities in percent. following is determined for how many pixel pairs the relative intensity difference has a particular one exceeds the percentage value. Thus, e.g. as threshold a relative intensity difference of 3%, 5 or 10%. From the number of pixel pairs, that exceed this threshold, let yourself immediately the measure determine. When viewing individual image areas may. it is different in size required, the measure to normalize. For example, the metric can always be based on the total number of the compared pixel pairs. Exceed z. B. in the present Example 100 of the 800 relative intensity differences has a value of 5%, it turns out for the normalized measure a value of 0.125 or 12.5%.

The characteristic measure thus obtained enables a simple evaluation of the image data with regard to the visibility. Will the picture be included? For example, divided into several individual Be rich, so the measure is determined separately for each of these. In order to determine the weather situation for an adaptive determination of the visibility, the following knowledge can be used purposefully: In the case of rain, it is to be expected that due to the inhomogeneous distribution of the raindrops on the disk, significantly different coefficients for an image will be determined for the individual areas. Since fog typically typically affects the entire image quite homogeneously, in this case the coefficients for different image areas of an image deviate considerably less or negligibly from each other. This allows the reliable distinction of rain and fog based on a simple criterion. Thus, the associated apparatus and process costs can be significantly reduced.

Also the temporal course of the image data and thus the measure can be advantageously for determining the current weather situation for one use adaptive visibility. Typically, it changes by raindrops striking the disc the contrast and thus the measure from an image to a subsequent image clearly. In contrast this change occurs the measure when fog occurs much slower and steadier. Of the temporal course of the measure for the Contrast or sharpness thus provides an additional Criterion for distinguishing different weather situations. About that In addition, this approach allows the determination in a simple way the intensity from precipitation. The precipitation intensity can turn out without much effort the time course of the measure M can be derived from individual image areas or entire images and how the weather situation provided to the vehicle user become.

A Combination of both area and temporal consideration the measure increases the recognition security for different weather situations or the visibility of visibility.

In particularly advantageous manner the measure to use certain vehicle components or to control. So it has proven, for example, in the detection of a Visibility under one. given threshold, due to fog or rain by the inventive method, the windscreen wiper automatically turn on the vehicle or the wiper speed adjust accordingly. In similar Way lets cause the switching on of the driving lights and / or the fog lights. Another advantageous variant is to influence the longitudinal control a vehicle in which a limiter depending set the determined visibility or the weather situation or the ACC - Adaptive Cruise Control - accordingly is controlled.

In can advantageously to determine the measure Image data will be used in a given period of time or after an action of a vehicle component. It has proved to be particularly advantageous here, for example the situation immediately after a wiping process of the windscreen wiper to use to improve the process. The fact that the remaining after wiping on the disc thin water film not on the picture quality the image data captured by the wiped area of the disk affects exploit themselves to gain very meaningful, low-interference image data. It is also optionally possible image data acquired in the period immediately after a wiping operation for one Comparison of the image data of several following the wiping process To use pictures. The recorded immediately after the wiping process Image data can be used as reference image data, whereby the reliability the method according to the invention is further improved.

As well It is advantageous, the image and a possible treatment to adapt the image data to the prevailing weather situation. For example it is desirable certain parameters for the image processing or image processing or image reproduction depending on the current weather situation or visibility. For example has it proven determined by an image recording device intensity values different values for to associate the representation of the image in an image display device / display. For this purpose, a determination of the visibility in the environment of Vehicle necessary. A recourse on data from separate additional Sensors is not necessary.

In a further advantageous embodiment of the invention dependent from the current value of the measure various information or instructions for a driver shown. Particularly advantageous here is the display of for each situation Recommended straightening speeds for the respective visibility for example, stored in a storage unit; just in low visibility due to fog or rain, it has been shown that many drivers for the driving each situation inappropriately fast. Here, the inventive method make a significant contribution to traffic safety.

It has proven particularly useful not only to evaluate an area of the captured image in terms of the characteristic measure, but several areas, these areas being selected in particular in the edge areas, in particular in the upper edge area or in the lower edge area. By means of this particular selection of the upper or lower edge region, it is possible to limit the influence of interfering causes, in particular of stray light sources, and thus a very effective evaluation of the regions with regard to the characteristic dimensional number, in particular in the case of the consideration of the backscattered light , to build.

there it has proven to be particularly effective the respective determined metrics merge and together for investigation. It's special proven, to form an average or in a two-step process first To exclude extreme values, ie particularly unbelievable values, and from the remaining a common measure and thus a visibility based on a common evaluation of the areas to create. This visibility has proven to be particularly reliable.

Preferably, the environment of the vehicle is illuminated and the backscattered light is captured with the image data captured by a camera and an intensity-dependent measure of the detected, backscattered light is formed and used to determine the range of vision using the referencing. In this case, the invention makes use of the knowledge that the lower the visibility, the more light is reflected and, accordingly, the intensity of the backscatter signal is increased. This relationship leads to the fact that with fog, thus with low visibility distances, the number of the backscattered high intensity values is substantially increased, which the 1b can be clearly seen, whereas at high visibility, so for example without fog, the number of high intensity values is low. As a measure of the intensity distribution, a normalized width of the histogram curve (for example, half-width or width at one-fifth of the maximum value) has proven particularly useful in this histogram representation.

Furthermore has it proven the upper or lower part of the picture is resolved horizontally the intensity evaluate and as a measure the height the intensity to use.

In the 2a For example, a typical horizontal intensity distribution of the detected backscattered light from the upper edge region of the image of the camera is shown for different views. It is striking that with decreasing visibility the simple maximum of the intensity distribution increases. This maximum is used as a typical measure for the determination of the visibility on the basis of the intensity-dependent evaluation of the upper image area. In addition to using the maximum, it has also been proven to use the area or a relativized maximum.

A comparable situation is in 2 B shown. This shows the horizontal intensity distribution of the backscattered light in the lower part of the image. Particularly noticeable here is the increasingly pronounced decreasing visibility of the formation of the camel tuber structure of the intensity distribution. On the basis of the height of the maxima or the surface can be determined in a corresponding manner as in the aforementioned evaluation of the upper image area a characteristic measure of the visibility. Due to the special selection of both the upper and the lower area is particularly ensured that disturbing light sources interfere with the determination of the characteristic measure and thus the determination of the visibility only to a small extent, since in these areas, only a few stray light sources are present. This procedure is not limited to the top or bottom of the image. If, in particular, a middle region of the image is used, additional measures are used to eliminate the interference of the received light caused by stray light sources and thus the change in the light distribution. This is done for example by selecting the area with active and thus interfering light sources with subsequent removal or replacement of the image data of these areas with less disturbing image data. This leads to a reliable result of the visibility estimation.

Preferably, a combination of the intensity-dependent evaluation of the backscattered light is carried out together with the evaluation of the image data in terms of sharpness or contrast at night. This combination at night ensures in particular that an optimized and particularly safe visibility determination is possible. The advantages of the two methods for determining the measure and their interpretation complement each other to a particular extent. On the one hand, in the typical central region of the image with its regular many objects with sharp edges or clear contrasts, an evaluation according to sharpness or contrast is particularly easy, whereas in the edge region just at night - regardless of the presence of objects - the evaluation after the intensity course of the backscattered light is particularly meaningful. This leads to a holistically closed, very efficient method for the quantitative estimation of the visibility. Whereas it has proven particularly useful not to use the backscattered light in sufficient daylight to determine the characteristic measure, as this of the given by the sunlight Störlicht note is influenced. By day, preferably only one determination of the characteristic measure based on the sharpness or the contrast is used. This leads to a very safe and cost-reduced in daylight.

there it has proven to be particularly effective the distinction between day and night situation by means of a Day / night sensor or by the switch position of the light or Distinguish direct from the captured image data and accordingly to provide the one or the combined evaluation.

Furthermore it has proven to be particularly effective the stored references, these are the correlated values between the characteristic measures and the associated visibility according to the VDI guideline - VDI 3786 - to verify what in particular be done regularly should. Used in verification, verification a need for change determined, these references are adapted accordingly. For this it has proven particularly useful to provide the vehicles with a distance measuring system, for example by a Distronik already existing in the vehicle, a so-called adaptive cruise control with radar evaluation, already available. Alternatively to this has it proven the image data with knowledge of the geometric properties of the image acquisition system and the objects to be imaged and from this the distance of the two vehicles respectively the object width. From the known weather conditions then the references can be verified and adapted if necessary. This succeeds in providing an up-to-date system for estimating the To determine visibility. Aging processes or other changes environment, for example by higher pollution or higher humidity and similar, can be considered automatically.

A Another embodiment of the invention relates to a device for estimating the Visibility in motor vehicles, which is particularly advantageous in a Device for improving the visibility in motor vehicles, for example in the form of an infrared night vision device.

The device according to the invention is described below with reference to a in 3 illustrated exemplary implementation explained.

It shows an image capture device 1 and an evaluation device 2 , The image capture device 1 Captures image data of the environment and guides it to the evaluation device 2 to. The evaluation device 2 It is designed in such a way that it evaluates at least one area of a captured image by generating a characteristic number characteristic of this area. This measure represents the sharpness or contrast or intensity distribution present in the area. On the basis of this characteristic measure can then be combined with references in one of the evaluation 2 associated memory 3 are stored, determine a corresponding visibility. The references are in the memory 3 chosen so that they correspond to the visibility defined by the VDI guideline. The through the evaluation 2 certain visibility is then the user of the vehicle in which the device according to the invention is arranged by means of a display 4 output. In this case, the output of both the visibility and a the visibility corresponding recommended maximum speed or an optical warning signal or the like to the object.

In addition, by means of the determined visibility with the aid of a control unit 5 Control signals for controlling vehicle components such as headlights, wipers, speed limiters or the like formed and forwarded to this. In addition to the preferred training of the display 4 or the control unit 5 is a radiation source 6 provided by the image capture device 1 covered area of the vehicle environment at least partially illuminated. This ensures that, on the one hand, sufficient illumination of the detected environment is ensured, and that an evaluation of the image data in terms of sharpness or contrast or the intensity distribution of the backscattered light to form the characteristic measure is made possible to a particular extent. The device according to the invention ensures a very safe and meaningful estimation of the visibility in a vehicle.

After a particularly preferred embodiment of the device according to the invention An adaptation unit is provided which is currently in communication with a device for determining the distance from preceding ones Suitable vehicles, the visibility according to the VDI directive VDI 3786 to determine in a different way and this in relation to to set the current characteristic measured variables. Kick noticeable Differences, the previous references are adjusted. To step There are no significant differences, the previous references unchanged maintained. This device is an adaptive adaptation the references and thus an adjustment of the visibility determination changed Framework conditions caused by changes created on the system or the environment created.

It is particularly advantageous to the invention to realize a proper device as an infrared vision enhancement system. For this purpose, the image capture device is realized for example as an infrared camera. Thus, the device shows especially for use as a night vision system particularly positive properties - even at night can be obtained from the emitted or scattered by objects from the vehicle environment infrared radiation images that compared to conventionally, for example. In the visible spectrum recorded images have an increased information content.

In a further advantageous realization of the invention is additionally a Radiation source provided that at least partially from the Illuminated image capture device captured area. This detected Area includes parts of the vehicle environment and parts of the vehicle window, through the environment is captured. This lighting can be timed and / or locally limited (for example 50 ms per second or only in one certain image area), not the functionality of the visual enhancement too strong to affect. So it is for example advantageous in a lighting with the additional Radiation source, the display of the image pickup device temporarily suppress the recorded image. By this procedure the driver becomes irritated by the vision enhancement system added additional. Radiation avoided.

It has about it proven, as additional Radiation source to use an infrared source. First, it is in the realization of the device according to the invention as an infrared night vision system due to the sensitivity of the image capture device in the infrared Spectral range necessary, as an additional source of radiation use source emitting in this area; secondly by this choice of emitted radiation in the non-visible spectral range achieved by the short radiation pulses for weather determination (rain sensor mode) an irritation of the driver or the surrounding traffic is largely avoided. Thus, the device of the invention carries both active and passive traffic safety.

A Further embodiment of the invention relates to a system for detection of references for the implementation a method according to the invention or the realization of a device according to the invention.

there the system shows two vehicles. The preceding vehicle is with a light source for the rear emission equipped with light or infrared radiation of predetermined intensity.

On second, subsequent vehicle is equipped with a device for determination equipped the distance to the first vehicle. This device presents for example, a distance radar system or a lidar system or a optical system, due to the known geometric properties of the Imaging system on the distance between the two vehicles conclude leaves. About that In addition, the second vehicle is equipped with an image capture device and an evaluation provided in the knowledge of the distance the received signal intensity as well as the given intensity the transmission and hence the visibility according to the VDI directive VDI 3786 determined. Similarly, the second vehicle also with a device according to the invention for estimation the visibility provided in the manner described above the relevant characteristic measure determined and these two sizes that determined visibility and the characteristic measure, as Value pair and thus saved as a reference. This is the basis for the Creation of reference tables for storage in a memory in a device according to the invention or for implementation created the method according to the invention.

Claims (19)

Method for the quantitative estimation of the visibility in vehicles, wherein image data from the environment are detected and evaluated for the estimation of the visibility, characterized in that at least one area of a captured image is evaluated to form a characteristic measure that this measure by means of a reference, which sets the measure in relation to a range of visibility, a visibility is determined and that the determined visibility for the output and / or control of vehicle components is used. Method according to claim 1, characterized in that that the evaluation of the image data based on a measure of the sharpness or the contrast of the picture is made. Method according to claim 2, characterized in that that the metric from the differences of the intensities adjacent or surrounding pixel is determined. Method according to one of the preceding claims, characterized characterized in that based on the time course of the image data on the nature of the visibility limiting disturbance such as fog in particular or rain is closed. Method according to one of the preceding claims, characterized characterized in that the measure or the determined visibility for the control of vehicle components especially windscreen wipers, driving lights or adaptive cruise control is used. Method according to one of the preceding claims, characterized characterized in that based on the measure or the determined Visibility parameters for a picture editing, image processing or image output can be selected. Method according to one of the preceding claims, characterized characterized in that for determining the measure or the determined Visibility image data can be used only in a specific Period before or after an action of a vehicle component in particular a windshield wiper were recorded. Method according to one of the preceding claims, characterized characterized in that depending on the measure or the determined visibility to an operator different Information or information, in particular, visibility, recommended maximum speed, recommended minimum distance, warning signals are displayed. Method according to one of the preceding claims, characterized characterized in that several areas of a captured image in particular in its peripheral areas to form characteristic measures be evaluated and this together to determine the visibility be used. Method according to one of the preceding claims, characterized characterized in that the environment of the vehicle is illuminated, that backscattered Light is detected as image data that an intensity-dependent measure of the detected backscattered Light is formed to determine the visibility. Process according to claims 2 or 3 and 10, characterized characterized in that both a measure of the sharpness and the contrast of the image and an intensity-dependent measure for the detected backscattered Light formed and used together to determine the visibility become. Method according to claims 2 or 3 and 10 or 11, characterized in that at night both a measure of the sharpness or the contrast of the image and an intensity-dependent measure of the detected backscattered Light formed and used together to determine the visibility and only a measure by day for the sharpness or used the contrast of the image to determine the visibility become. Method according to one of the preceding claims, characterized characterized in that the stored references verified be adjusted if necessary. Device for estimating the visibility in motor vehicles with an image capture device and an evaluation device to estimate the Visibility, characterized that the evaluation device suitable is, at least one area of a captured image to evaluate the formation of a characteristic measure, to this measure by means of a reference, which the measure in relation to Visibility sets, a visibility to determine and the determined visibility for the output and / or control of vehicle components to disposal to deliver. Device according to claim 14, characterized in that that the image capture device is an infrared camera is. Device according to one of claims 14 or 15, characterized in that a radiation source is present, with which one of the image recording device detected Area is at least partially illuminated. Device according to claim 16, characterized in that that the radiation source emits infrared radiation. Device according to one of claims 14 to 17, characterized that the stored references by means of an adaptation unit be verified and adjusted. System for recording references for a procedure or a device according to any one of the preceding claims, characterized in that a vehicle with a light source for backward emission of light or infrared radiation of predetermined intensity and on second vehicle with a device for determining the distance to the first vehicle, an image capture device and an evaluation device, in the knowledge of the distance, the received signal intensity as well the given intensity the transmission and from this the references calculated, provided is.