1、SAE Technical Standards Board Rules provide that: “This report is published by SAE to advance the state of technical and engineering sciences. The use of this report is entirelyvoluntary, and its applicability and suitability for any particular use, including any patent infringement arising therefro
2、m, is the sole responsibility of the user.”SAE reviews each technical report at least every five years at which time it may be reaffirmed, revised, or cancelled. SAE invites your written comments and suggestions.TO PLACE A DOCUMENT ORDER; (724) 776-4970 FAX: (724) 776-0790SAE WEB ADDRESS http:/www.s
3、ae.orgCopyright 2000 Society of Automotive Engineers, Inc.All rights reserved. Printed in U.S.A.SURFACEVEHICLE400 Commonwealth Drive, Warrendale, PA 15096-0001RECOMMENDEDPRACTICESubmitted for recognition as an American National StandardJ2396ISSUEDJUL2000Issued 2000-07Definitions and Experimental Mea
4、sures Related to the Specification ofDriver Visual Behavior Using Video Based TechniquesForewordThis document is intended to be as consistent with the International Organization for Standardization(ISO) 15007 standard as possible and is developed to extend that document to include factors which affe
5、ct theresults of video based visual allocation studies.1. ScopeThis SAE Recommended Practice defines key terms and metrics applied in the analysis of videobased driver eye glance behavior. It can be applied in environments from real world trials to laboratory baseddriving simulator studies evaluatin
6、g Transport Information and Control Systems (TICS). The proceduresdescribed in this document could also apply to more general assessments of driver visual behavior in theabsence of TICS or other advanced display and control systems associated with Intelligent TransportationSystems (ITS). Driver work
7、load studies, design of traffic control devices and roadways, modality interferencefrom use of cell phones, mirror redesign, situational awareness, and the effects of driver stress from sleep lossand trip delays are just a few of the studies that would benefit from a standard practice for measuring
8、visualallocation. The metrics and definitions described as follows are intended to assist development of a commonsource of reference for driver visual behavior data. With specification of independent variables, data collatedand analyzed from this document allow comparisons to be performed across dif
9、ferent device evaluations andexperimental scenarios. It should be noted that the following definitions and measures would also apply toeye movement techniques. This document does not include the use of “head-up” displays. This documenthas been developed under the supervision of the SAE Safety and Hu
10、man Factors Committee.1.1 IntroductionVision provides the primary source of information available to the driver. Information isgathered by looking at objects and events, which in turn enables decision-making, control, and navigation ofthe vehicle in the road traffic environment. Assessment of driver
11、 visual behavior (eye glance behavior)provides a method to quantify the drivers visual allocation to the roadway, traffic control devices, in-vehicleinformation sources, controls and mirrors and as such can be a useful tool in many ergonomic studies of thedriver. These would include evaluation of th
12、e visual demands of in-vehicle information devices, assessment ofvisual distraction, driver fatigue, workload, individual differences (e.g., novice versus expert) and basic studiesof visual allocation in driving.TICS and other advanced display and control systems associated with ITS can present a ra
13、nge of driverrelated information. If these visual displays have associated controls (e.g., to select a zoom level or menuoption), then the associated hand-controlled activities may also be visually guided and become part of thevisual demand associated with a display application. For this reason, it
14、may be important to consider not onlythe visual behavior in relation to information display, but also the duration and frequency of glances associatedwith driver control actions.COPYRIGHT Society of Automotive Engineers, Inc.Licensed by Information Handling ServicesSAE J2396 Issued JUL2000-2-In the
15、past, comparisons between separate evaluations of specific vehicle systems in different testenvironments have been made more difficult by dissimilar approaches in experimental techniques, operationaldefinitions and analysis methods.This document has been developed to give guidance on the terms and m
16、easures relating to the collection andanalysis of driver visual behavior data. This approach aims to assess how drivers respond to vehicle andequipment design, the road environment, or other driver related tasks in both real and simulated roadconditions. It is based on the assumption that efficient
17、processing of visual information is necessary to the safeperformance of the driving task in a given driving situation. Practical assessments of drivers in real or simulated environments are conducted to quantify the allocation ofvisual behavior to specified targets. It may be quantified by the locat
18、ion, duration, and frequency of glances toa specified target in the visual scene. This approach often employs commonly available video-recordingequipment. However, it does not preclude the use of more sophisticated technologies such as eye movementtechniques, which may elicit additional driver visua
19、l behavior information. See Appendix A for a generaldiscussion on capture techniques for video based eye glance data.2. References2.1 Applicable PublicationsThe following publications form a part of this specification to the extent specifiedherein.2.1.1 ISO PUBLICATIONSAvailable from ANSI, 11 West 4
20、2nd Street, New York, NY 10036-8002.ISO/CD 15007-1 (1997)Road vehiclesMeasurement of driver visual behavior of transport informationand control systemsPart 1: Definitions and metricsISO/CD 15007-2 (1997)Road vehiclesTransport information and control systems: Equipment andprocedures related the measu
21、rement of driver visual behaviorPart 2: Test Report2.1.2 CITED PUBLICATIONSBarickman, F. (1998), “Intelligent Data Acquisition for Intelligent Transportation Research,” (SAE TechnicalPaper No. 981198), Warrendale, PA: Society for Automotive EngineersHowett, G. (1983), “Size of Letters Required for V
22、isibility as a Function of Viewing Distance and ObserverVisual Acuity,” National Bureau of Standards Technical Note 1180,” Washington, DCKiger, S., Rockwell, T., and Tijerina, L. (1995), “Developing Baseline Data on Heavy Vehicle Driver VisualWorkload,” Proceedings of the Human Factors and Ergonomic
23、s Society 39th Annual MeetingYarbus, A. (1967), “Eye Movements and Vision,” New York: Plenum Press2.2 Related PublicationsThe following publications are for information purposes only and are not a requiredpart of this document.American Psychological Association (APA) (1994), “Publication Manual of t
24、he APA,” 4th edition.Washington DC (see Statistical Measures)Dingus, T. (1997), “Effects of Age, System Experience, and Navigation Technique on Driving with anAdvanced Traveler Information System.,” Human Factors, 39, 177-199Dingus, T., McGehee, D., Hulse, M., Jahns, S., Manakkal, N., Mollenhauer, M
25、., and Fleischman, R.(1995), “TRAVTEK Evaluation Task C3 - Camera Car Study,” (Tech. Report FHWA-RD-94-076).McLean, VA: Office of Safety and Traffic Operations Research and DevelopmentFairclough, S. H., Ashby, M. C., and Parkes, A. M. (1993), “In-Vehicle Displays, Visual Workload andUsability Evalua
26、tion,” Vision in Vehicles - IV, 245-254, A. G. Gale et al., Eds. Elsevier SciencePublishers B. V. (North-Holland)COPYRIGHT Society of Automotive Engineers, Inc.Licensed by Information Handling ServicesSAE J2396 Issued JUL2000-3-Lansdown, T. C. (1997), “Visual Allocation and the Availability of Drive
27、r Information, Traffic and TransportPsychology: Theory and Application,” 215-223, T. Rothengater and E. Carbonell Vaya, Eds.Amsterdam: PergamonRockwell, T. H. (1988), “Spare Visual Capacity in Driving-Revisited: New Empirical Results for an OldIdea,” Vision in Vehicles - II, 317-324, A. G. Gale et a
28、l., Eds. Elsevier Science Publishers B. V. (North-Holland)Snyder, H., and Monty, R. (1986), “A Methodology for Road Evaluation of Automobile Displays,” Vision inVehicles, 227-237, A. G. Gale et al., Eds. Elsevier Science Publishers B. V. (North-Holland)Taoka, G. (1991), “Distribution of Driver Spare
29、 Glance Durations,” Transportation Research Record No.1318 Safety and Human Performance. National Research Council. Washington, D. C. Tijerina, L., Kiger, S., Rockwell, T. H., and Wierwille, W. W. (1996, October), “NHTSA Heavy VehicleDriver Workload Assessment Final Report SupplementTask 5: Heavy Ve
30、hicle Driver WorkloadAssessment Protocol,” (DOT HS 808 467). Washington, DC: National Highway Traffic SafetyAdministrationTijerina, L., Kiger, S., Rockwell, T. H., and Tornow, C. (1996, October), “NHTSA Heavy Vehicle DriverWorkload Assessment Final Report SupplementTask 7A: In-cab Text Message Syste
31、m and CellularPhone Use by Heavy Vehicle Drivers on the Road,” (DOT HS 808 467), Washington, DC: NationalHighway Traffic Safety AdministrationWierwille, W. (1981), “Statistical Techniques for Instrument Panel Arrangement,” In J. Moraal and K.Kraiss (Eds.), Manned Systems Design: Methods, Equipment a
32、nd Applications (pp.201-218), NewYork: Plenum PressWierwille, W. (1993), “Visual and Manual Demands of In-Car Controls and Displays,” In B. Peacock andW. Karwowski (Eds.), Automotive Ergonomics (pp. 299-320), London: Taylor and Francis.Wierwille, W. (1993), “Demands on Driver Resources Associated wi
33、th Introducing Advanced Technologyinto the Vehicle,” Trans. Res. C, Vol 1, No. 2, pp.133-142. Great Britain: Pergamon Press Ltd3. Definitions3.1 Direction of GazeThe target (see Figure 1) or target location to which the eyes are directed.3.2 Dwell TimeThe sum all fixations and saccades within the ta
34、rget area between transitions or shifts of gaze toother target areas (see Figure 2).3.3 FixationAlignment of the eyes so that the image of the fixated target falls on the fovea for a given timeperiod.3.4 FrameThe basic unit of observation for data reduction based on the video data capture rate. It i
35、s one of thesuccessive pictures recorded on a videotape or on digitized video. The data reducer (or data reductionsoftware) examines a video display of the drivers eyes frame by frame, to determine the driver eye fixationlocation.3.5 Glance DurationThe time from the moment at which the direction of
36、gaze moves toward a target (e.g., theinterior mirror) to the moment it moves away from it. This includes the transition time to that target (see Figure2). A single glance duration may also be simply referred to as a glance.3.6 Glance FrequencyThe number of glances to a target within a pre-defined sa
37、mple time period, or during apre-defined task, where each glance is separated by at least one glance to a different target.3.7 Glance Location ProbabilityThe probability that the eyes are fixated at a given target (location) during asample interval. This would be defined as the frequency of glances
38、to target A divided by the number ofglances to all targets in the sample.COPYRIGHT Society of Automotive Engineers, Inc.Licensed by Information Handling ServicesSAE J2396 Issued JUL2000-4-3.8 Link Value ProbabilityThe probability of a glance transition between two different locations. Operationally,
39、the link value probability between target locations A and B is defined as the number of glance transitions fromA to B plus the number of glance transitions from B to A; this sum divided by the total number of glancetransitions between all pairs of locations in the sample interval.3.9 SaccadeThe brie
40、f movement of the eyes between fixations. See Figure 2.3.10 Sample Interval (period)A reference time period that constitutes a sample of interest (e.g., an in-vehicletask or maneuver) in the video data. Usually, this will be the time associated with a reference event.3.11 Separation Angle (in-vehicl
41、e devices)The angle subtended at the eye between the center of two in-vehicle targets. This angle should be 20 degrees unless a sampling to such targets is commanded or ifcalibration demonstrates better discrimination.3.12 Target (Target Location)A pre-determined area within the visual scene, (e.g.,
42、 a rear view mirror). SeeFigure 1. For commanded visual tasks it can be a specific instrument.3.13 Time Off Road SceneThe total time between two successive glances to the road scene that are separatedby glances to non-road targets. If this is the sole emphasis in a test, use strategy “d” on page six
43、 for glancedefinition in data reduction (i.e., include both transitions to and from the road scene).3.14 TransitionA change in eye fixation location from one defined target location to a different target location.3.15 Transition TimeThe duration between the end of the fixation on a target location a
44、nd the start of the fixationon another target location. See Figure 2.3.16 Visual Display (TICS or ITS device)A device used to present information or a control which requires visualfixations to locate and operate.3.17 Visual Angle (for non-road scene targets)The angle subtended at the eye by the larg
45、est dimension of aviewed object.4. Measuring Eye Glance Behavior in DrivingTo put the previous terms in context, it is important tounderstand the process of visual perception through saccadic eye movements. The main function of asaccade is to change the point of fixation to direct the most sensitive
46、 region of the retina (the fovea) to aparticular object of perception (Yarbus 1967). These saccades are typically less then 20 degrees in amplitudeand have an angular velocity of up to 400 degrees per second. After one or more saccades, fixations of 0.2 to0.4 s are made to process information. A gla
47、nce is considered as a series of fixations at a target area until theeye is directed at a new area. Operationally, the glance duration includes the prior transition time (to beconsistent with ISO 15007). These transition times typically range from 0.10 to 0.5 s depending upon thedistance between the
48、 two targets. Dwell time is defined as the glance duration minus the prior transition timeor the sum of all fixations and saccades in the target area between transitions or shifts of gaze to other targetareas. See Figure 2.With sophisticated eye movement systems, it is possible to measure the durati
49、on of fixations and transitiontimes. However, for video based systems, accuracy is limited to static target glance durations (usuallybetween 0.5 to 3+ s). It should be noted that gazes to the road usually involve several glances. A graphicaldepiction of the visual allocation process describes the definitions to follow. See Figure 1.The chronological relationship of driver visual allocation between and among targets is illustrated in Figure 2.Each horizontal segment represents a fixation (alignment of the eyes so that an image of the fixated target fall
