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Ask Slashdot: Image Recognition For Race Timing? 170

Posted by timothy
from the show-your-work dept.
First time accepted submitter int2str writes "Autocross is a form of motorsports practiced in the U.S. and around the world where car enthusiasts explore the capabilities of their car in an open parking lot or similar suited area. It's point-to-point racing (not closed circuit). Most of these events are organized by car clubs and volunteers. Timing is usually done with a form of detection beam at start and finish that gets interrupted by the car crossing the beam. Many commercial systems are available. All of these system require the operator to enter the car's number or ID and requires the cars finishing in the order they started. So if one car is not able to finish, the operator has to intervene, or timing is broken. For closed circuit racing, transponder systems are available to address this problem. But such systems require sensor loops in the track or overhead (bridge setup) and the transponders are expensive. Do you think it would be possible to design a timing system using off-the-shelf parts and open source solutions to uniquely distinguish about 100 participating vehicles and time them from a start to a finish point, independently of their finishing order?" Read below for some more details:
int2str continues: "My initial idea would be:
  • Use (web-?)cameras at each end that feed into a Linux based notebook (USB/Ethernet).
  • Start recoding still images as fast as possible when motion is detected
  • Identify unique shape, numbers, barcode, qr code or similar in the images, that have been attached using a magnet to the vehicle's door.

Difficulties to overcome:

  • Camera with high enough shutter speed to get recognizable image of vehicle traveling 30-60mph
  • Quickly and accurately identify a unique symbol or shape

So far I've started looking into OpenCV as a possible tool for image recognition, but have not been able to find a capture solution. Does anybody have experience with something like this? The solution would be open source and well documented as to benefit the many car clubs around the country and the world."

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Ask Slashdot: Image Recognition For Race Timing?

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  • by pspahn (1175617) on Friday October 28, 2011 @07:06PM (#37875064)
    • Timer on board vehicle
    • Timer starts as it leaves starting line
    • Timer stops as it crosses finish line
    • Timer info is sent to controller

    What exactly is the problem here?

    • by TubeSteak (669689)

      What exactly is the problem here?

      The problem is that your solution requires us to trust the client.
      Not only should you never trust the client, you should assume the client is hostile and act accordingly.

      • by tlhIngan (30335)

        The problem is that your solution requires us to trust the client.
        Not only should you never trust the client, you should assume the client is hostile and act accordingly.

        So put timer inside a box with serially numbered seals. Timers are issued at start of event and must be returned at end. If seal has been tampered, vehicle it was tracking is disqualified.

        If necessary, issue them on start line and collect them at finish line. Have simple loops at start and finish line to automatically start and stop timer.

        • by 6Yankee (597075)

          Seals seemed to work well enough when I was hanging around gliders. I distinctly remember someone going for a height achievement, and the barograph (old-school, pen on paper drum) being started and wrapped in tape, which was then signed across the joins by several witnesses. The barograph was completely inaccessible in flight anyway, but the simple ideas are often the best.

          I don't recall any such precautions for the (film) cameras they used to photograph waypoints on distance attempts, but I suppose it woul

      • by pmontra (738736)
        Agreed, but it works in bicycle racing, and people race in bunches and teams there. Never heard of anybody tampering with the transponders. Your cars should arrive alone and if the transponder doesn't match the car you disqualify it.
        • Agreed, but it works in bicycle racing, and people race in bunches and teams there. Never heard of anybody tampering with the transponders. Your cars should arrive alone and if the transponder doesn't match the car you disqualify it.

          It doesn't work all that well in bicycle racing-- if you're using chips, you still need a good camera at the finish, and if you have a good camera at the finish you don't need chips. Chips are a convenience for picking order in the middle/back of the pack, but aren't good for picking close finishes. I've never seen any published data on the spatial resolution of the chip systems (and asked the sales people directly because they were trying to sell it to me). The demos I've seen for track racing (I did a

    • by xtal (49134)

      Detecting the finish line is one problem.

      Detecting multiple cars crossing the finish line within a few ms is another problem.

      Trusting the client is another issue.

      Price is another..

      • by fluffy99 (870997)

        Detecting multiple cars crossing the finish line within a few ms is another problem.

        Autocross usually doesn't have multiple cars that close to each other. They are staged and sent on the track at intervals. Sometimes as the poster pointed out, they will pass each other and finish "out-of-order" which confuses a timing system that assumes FIFO/LILO.

    • Autocross generally charges $20ish as an entry fee... the timer onboard vehicle would raise the barrier to entry higher than most clubs would want (due to cost / complexity for newcomers.)

      • Timer stops as it crosses finish line

      What exactly is the problem here?

      Was already mentioned in the summary question. Transponder location is the problem. You fall down on the detection of where the finish line is.

  • Some large numbers on the sides or hood of the car would make image recognition, if not trivial, at least relatively simple.

    • Numbers on the cars are more or less standard, but are usually a mixture of different types, including shoe polish on the windows - OCR would be... challenging.

  • by Antisyzygy (1495469) on Friday October 28, 2011 @07:13PM (#37875118)
    I worked in Face Recognition as a research assistant for my MS. I was part of a group designing a robust end-to-end system for the purposes of identifying people in a wide variety of conditions. This problem seems easier because you can assume that the cars will be in one location within one time frame, the camera is fixed and everything in your data set will cross this line unless they break down, they will have almost identical 3D structure (unlike the face), and you can expect some identifying marks on the front end that crosses the finish line. As long as you have some sort of identifying marks, you can use standard face/object recognition techniques to identify the vehicle. There are some pretty advanced algorithms out there. The best out there when I was actively working in face recognition was STASM and Pittpatt. Better yet, if you had some unique identifier expected at some part of the vehicle, you can easily make the problem much easier. For example, have each one use an infrared identification tag located in precisely the same spot relative to the build of the vehicle.
    • they will have almost identical 3D structure (unlike the face), and you can expect some identifying marks on the front end that crosses the finish line. As long as you have some sort of identifying marks, you can use standard face/object recognition techniques to identify the vehicle.

      The cars in autocross are as (and usually more) varied as what you see on the street. In a field of 100 competitors, you might expect to see 5 or 6 participants with a particular make/model, for the most popular (e.g. 6 Miatas, 5 Neons, 4 Corvettes, 4 Mustangs, and a hodge podge of all kinds of cars from the last 40 years.)

      • This is still more-or-less a significant domain reduction over the human face. If you weren't human you wouldn't be able to identify one face from another. Try identifying faces upside-down sometime in a split second. We are uniquely built to identify very small variations in the human face in upright position. I suspect the front end of a car would be much less difficult. For example, first classify what the make of the car is, then classify color, then classify markings. If you have a database of cars in
        • There is a practical issue with photographing the front (hard to protect the camera) - most timing equipment is located 30' to the side of the finish line (you can get closer at the start.)

  • Put giant QR code stickers on the hood/doors. Done.

  • by GrahamCox (741991) on Friday October 28, 2011 @07:15PM (#37875138) Homepage
    How about sticking a big barcode to the competition number panel and use a simple barcode scanner to ID the vehicle as the beam breaker is triggered?
    • by Dan East (318230)

      This is the cheapest / most versatile option, but you would use QR codes [] or other 2D codes designed specifically for this kind of image scanning and not traditional 1D "barcodes". Issues to consider would be lighting, the camera's ability to capture clear images at whatever speed the vehicle is moving at, etc.

      • by GrahamCox (741991)
        Using QR Codes is still complicated compared to simple barcodes. You need a fast camera, image processing, etc. That might be acceptable of course. But a simple laser barcode scanner is cheap and effective, and simpler to interface. You can print the barcode for the competitor on a sheet of office paper and stick it to a side window with tape. Super-cheap and likely to work. There could be a problem ensuring that several vehicles arriving at once were able to be scanned (that may not be an issue for the spo
  • by Anonymous Coward

    There is already an outfit doing motorcycle road racing using RFID. it would work in this instance as well.

    • I was going to suggest this. The stage rallies around here use optically triggered timing plus RFID for identification.

      The autocross group is on an even smaller budget so we use a guy with a stopwatch and a clipboard. It's good enough.

  • by Uksi (68751) on Friday October 28, 2011 @07:26PM (#37875226) Homepage

    I autocross and I've been thinking about the same problem. I even thought about writing my own free software and building plans for off-the-shelf/cheap-to-make transponders ($1200 for a wireless transmitter unit? jesus).

    The problem is that if a car doesn't finish and misses the timing mark--the software shoudl just let you to fix it up. You should be able to say "this car didn't finish" (has a missing tick) or "ignore this tick" (some corner worker tripped the lights accidentally). Then it shoudl be able to just recalculate the times affected. It seems so simple to me, I am baffled that it hasn't been implemented.

    All the cars starts in the same order, all the numbers are known at hte start time and cars never pass each other. So you have always same-sequence travel of cars. All you need to do is fix occassional lacks of ticks or extra ticks. No need to re-run the cars.

    • I also autocross, and I think a practical solution would be to add a network camera to each electric eye installation, connect them wired or wireless to a notebook, and simply snap photos as the beam is broken. Keep timestamp records for each beam break event, assume everything is running normally, but also do a fairly simple color check on the car to verify that the assumed finish time event matches the start event. Display a series of thumbnails on the screen for each automatically determined start/fini

      • You're on the right track here, but let's divide the task into subtasks.

        We don't need to produce a fully automated solution at the first iteration, so we set up the webcams and the beam-gates with synchronised clocks. Post-race, the software is used by the marshalls to verify timing thus: it lines up a table of screen grabs, each row representing what it thinks is one car, the marshall clicks "OK" if they all match, or either clicks a button to identify a "drop out" (at which point the following photos ar

    • Except for reruns, double driver cars, novices (or experts) who are late / get into the wrong grid slot. You can't assume the order is always the same.

      • by Uksi (68751)

        The starter always confirms the starting car's number at the starting line. So if someone gets into the wrong grid spot, it doesn't matter because their car number would be still correct at the starting line. If someone is driving someone else's car and doesn't inform timing appropriateyl, then you would have that problem anyway.

        Reruns are not an issue because they are just like regular runs, except done again for a special reason. Cars still line up at the starting line in a certain order to run a re-run.


        • ahh I see what you are saying. "All the cars starts in the same order" was not clear and made it sound like you meant for the entire heat they are always in the same order. Perhaps, "all the cars cross the finish line in the same order they started" would have been easier for me to understand.

    • by Zadaz (950521)

      A thousand times this.

      Your problem doesn't need complicated (and expensive) things like transponders, infrared identifiers or image recognition cameras. You're dealing with edge cases that a human can deal with in a few seconds if they have the right interface for it.

      Give them the right interface for it.

  • I'd suggest using the best software available: the human brain.

    Version 1
    Aim a camera at the finish line. Aimed to capture the racer's number and any other identifying information. Set the camera to be triggered by the interruption of an IR beam. Place a clock in the picture field.
    During / after the race, find each racer's picture and record the time.

    Version 2
    Aim a video camera at the finish line.
    Use a laser pointer as a finish line. Aim it at something white and make sure it is visible as a racer crosses

    • by swalve (1980968)
      I was going to suggest the same sort of thing. Two cameras in timesync with each other.
    • Re: (Score:3, Informative)

      by WebMasterP (642061)

      This won't work. Almost all forms of autocross guarantee a driver 3 runs (each driver does one run, then each driver does a second set, etc.). Knowing what time you have to beat after each run is a huge part of autocross. The data has to be input in real time, or at least close so that results can be viewed after each run. This problem gets worse with ProSolo, where there are two courses and challenges require results for a class to figure "handicap times". Additionally, multiple cars are on course at one t

    • Racers want to know their time when they cross the line or very soon after, not after their heat / event. The system needs to be reasonably realtime.

  • by LoudMusic (199347) on Friday October 28, 2011 @07:37PM (#37875326)

    What happens if two dudes show up in a blue Miata?

  • by Anonymous Coward on Friday October 28, 2011 @07:44PM (#37875380)

    They're similar to QR codes but optimized for the needs of robotics (similar to your needs).

    In robotics, the main need is for robust recognition, and accuracy.

    QR codes are much more complicated because they need a lot more "payload" bytes (millions of unique codes), whereas you only need to distinguish between a couple hundred codes

    there is even source code available:

  • by Anonymous Coward

    I have run timing & scoring for track events (I don't AutoX), but you are under-estimating the problem. Time tolerances for a winning finish can be as close as .0001 seconds. Any variation in the delay for a camera or the time needed to process the image could be a serious problem. Another problem would be car placement, cars will not always cross the line in a nice, neat manner.

    Those problems can have real monetary consequences when you factor in the product contingencies (free race tires and other

    • by flatulus (260854)

      Timing tolerances of +/- 100 microseconds?

      At 100 miles/hr (160 km/hr) that would be a distance of 0.176 inches (4.44mm).

      I think you meant "milliseconds" which is 0.001, not 0.0001. Still, multiply the above by ten and you get:

      1.76 inches or 44.4 mm

      That's a pretty awesome "photo finish."

      And for that matter, what about relativistic effects?

      • These are interesting numbers, and yes, I verified them with my own calculator.

        But it has been stated here that the race is fastest time over a fixed course, not a nose-nose competition between multiple vehicles. That makes the short difference of distance not very relevant.
  • by Anonymous Coward

    AForge has the components you need to compliment a IR system: motion tracking and object identification. I've used it on a similar project for a cup team to get corner exit ride heights and yaw. Camera shutter speed shouldn't be much of an issue with just about any off the shelf camera. Camera position will require a bit of testing but that will be pretty obvious. Using video as an alternative with an off the shelf camera is another matter. Here frame rates rule. Even if you jump through the hoops to

  • Automaticallt take your pics and upload to dropbox, pay mechanical turks to identify and enter data, profit!
  • How quickly can Bluetooth establish a connection? Use the optical beams to determine the time that a car passes a point, and give each driver a Bluetooth headset that has been paired with laptops used to record the timing.

    You can test the range to make sure it will work--you should only need a few meters. You can get cheap headsets for somewhere around $50, probably less.

    I have no idea if this would actually work, but it should be possible to do a test run with parts you probably already have.

    • Bluetooth isn't the right tech, you're looking for RFID in this case.

      • by crow (16139)

        Yes, RFID would be better, but something like Bluetooth or even turning on WiFi on a cell phone in the car could be sufficient, and it could eliminate the need to purchase equipment that isn't already on-hand. It also has a nice hack spirit if it works, in using something in ways beyond what it was designed for.

  • by Radical Moderate (563286) on Friday October 28, 2011 @08:09PM (#37875572)
    As a race organizer, timing chips are a PIA, it would be awesome if facial recognition could track everyone at the start and finish. We're talking up to 10,000 people though, and you'd have to have a photo on file to identify each person. The finish would be easy, everyone is spread out, but at the start you have a lot of faces crossing the starting line simultaneously. Aside from being kind of creepy, is it workable?
  • by flatulus (260854)

    I know this has a scalability problem (i.e. the cost of equipment goes up linearly with the number of contestants) but you could build a self-contained GPS device that tracks a car's position throughout the event. Have it record position information to flash as often as possible (Sparkfun has a GPS receiver that will update position 10 times/sec for US $61). At the end of the event, everyone turns in their GPS device and their position recordings are uploaded into a computer.

    Now one may argue that GPS pos

    • [] There are image processing techniques that would work with relatively small identification marks and a sufficiently "good enough" camera. The processing may take 5 minutes but you can cut to commercial and have a human verify it later. The issue is getting the original system accurate enough you are 99 percent sure whoever crossed the line first, crossed it. Facial recognition systems already have this level of accuracy. Just like voting syst
    • See

    • but too expensive to give to every driver and since newbies can walk on the day of the event the club would also need a good number of "loaner" units. Much like they do with loaner helmets.

    • by cojsl (694820)
      Current optical timing systems for autocross time to the thousandth of a second- and there are dead heats even then. So GPS is no where near accurate enough.

      Factoid- prior to national events two parallel timing systems are set up and tested against each other to ensure consistent results. IIRC, anything greater than 5 thousands variation between them calls a timing system into question.

  • by Anonymous Coward

    Don't know if it would work in auto sports but sounds like a use for RFID,

  • by cojsl (694820) on Friday October 28, 2011 @08:33PM (#37875714) Homepage
    I'm an autocrosser with experience setting up, maintaining, and troubleshooting both an older T&S system, and the new system used by the SCCA at national events. Ours was the first local region to install the new "national" system, so I'm familiar with the "issues" surrounding the current T&S options.

    There are several practical issues with optical systems for automated vehicle recognition- number and class markings are already tough to get consistent without requiring an additional barcode or QR large enough (some competitors would gripe about a huge barcode) to be useful at the 30'+ distance finish line sensors are set back to minimize getting hit by spinning cars. Add in the fact that existing markings some times fall off on course, or competitors in dual driver cars forget to change numbers between runs, and it's tough to be certain you'd have something consistent to try to recognize.

    The national T&S system uses a wireless barcode reader operated by a worker in the starting queue to read stickers placed on competitors helmets to register cars in the T&S software. Locally, we position the T&S trailer to allow the operators to manually enter vehicles as they enter the start queue. Human eyes really are the most flexible here "shouldn't 80ES be 180ES?".

    I like one of the comments above about a webcam triggered by the finish light taking a picture with a clock display in it. Unless there was OCR to immediately post the result to the software, the results feedback would be too slow for our region- we have real time announcement of finish stats, and the software can post results to a web server real time for smartphone access in paddock. The T&S software uploads a small file to the web server in the 20ish second gap between finishing cars.

    Apologies for not offering solutions, but hopefully the extra info about some of the issues can help shape a solution.

    • The national T&S system uses a wireless barcode reader operated by a worker in the starting queue to read stickers placed on competitors helmets to register cars in the T&S software.

      At my local events, there are usually a few people sharing loaner helmets...

  • This is pretty much a tracking problem, I would use the open source Predator Tracking algorithm to track each of the car simultaneously. The problem I see is if it is going to be fast enough for 100 cars, but it is worth to investigate it. [] Alternatively, thinking about using open source-hardware as a solution, use the open source Arduino Micro-controller Piece the sensor you need, and you will have your system at a much lower price ! []
    • Don't know if Predator refers to the military UAV, but it got me thinking, float a camera on a balloon and video the whole track from above....

  • Why not put an RFID tracker on each car? They're relatively cheap and you can store some encrypted identifier in it. Pillar or mat sensors would pick up when the car crosses the line, though it might be a challenge finding sensors that'd pick up a car at 60mph...

  • Special paint that reflects/absorbs only at certain frequencies. You have a 'stickers' that go on all four corners of the vehicle. The finish line has a spread-spectrum laser array blasting across it. When a car crosses the line, each car is tagged with unique tape. The laser light reflected will be unique to the vehicle. You triangulate the reflected lights timings and use that in conjunction with the wavelength reflected back and you've got a car and you've got a time.

    Unique tape on each car. Cheap, replaceable. Not a perfect solution, but some variant of this involving selected emission/absorption is a winning ticket. I made this up in 1 minute and have no idea if there are any preexisting solutions that do this. For the pedants; yes tape could peel off and yes people could cheat some how I'm sure, blah blah blah, and I'm sure there is a more optimal solution blah blah blah, and I'm sure you'll have issues in X Y Z situation with A B C conditions blah blah blah. Go make something better and sell it.
  • There has been a lot of work for recognizing images in video. Here, if you're smart you should be able to do the recognition given a single still, which means it's just ordinary image processing after extraction from the video.

    Make it easier on yourself by making the numbers something like bright yellow on blue with a white border (for instance). Then just look for segments of each image with high response for yellow and blue. Then extract the video and pass it through an OCR tool.

    Also, put the camer

  • by w0mprat (1317953) on Friday October 28, 2011 @09:14PM (#37875966)
    Accuracy hard to achieve. You'd have to carefully track the latency between the webcams image and the software timestamping the video data. Not an easy coding excercise, and would require calibration with accurate timing equipment. This latency also better be stable. I don't know too much about using linux for realtime work but I have heard it has some latency issues at the kernel level that causes trouble for audio pro's.

    If you want to do this with a web cam and a bit of code on a linux machine, well 30fps video gets you a lower bound of 33ms time resolution. That's before the camera feeds to the USB data channel, then any gamer will tell you USB has some latency, and then software has to process the image data. High powered laptop and a good camera might be able to do all this as low as 100ms before it can timestamp the data. Image processing for identifying the vehicle can then happen at any time. This would need to be carefully accounted for in deciding who wins a race.

    Proper race timing needs to be 3 decimal places, at 200kph (124mph) a 1/1000th of a second ammounts to 6cm of difference. Races are really won and lost on as little as this and often the timing is done even finer.
    • by Bob9113 (14996)

      Proper race timing needs to be 3 decimal places, at 200kph (124mph) a 1/1000th of a second ammounts to 6cm of difference.

      Good math.

      AutoX is much slower than that. This may not work for F1, but F1 can afford the fancy equipment.

      AutoX top speed is well below 100kph on most tracks, and you can put a turn near the finish line to keep the speed across the line under 50 kph (I suspect the turn near the finish is pretty common anyway, to keep the course exit speed down). It's also rarely more important than who bu

  • First, I'm not familiar with car racing so apologies if my observation is idiotic.

    The problem I see with having bar codes or RFID measure the time is how the car crosses the finish line. Because the OP mentioned a beam being interrupted I imagine the finish is determined by the front of the car touching the finish line (not unlike any other type of racing) so if the time is measured by a barcode or image on the roof or door then how do you match that with the front of the vehicle. Also, if the time is m
    • by cojsl (694820)
      Not idiotic at all, you made good inferences. The current popular systems have an optical beam transceiver and reflector pair at both the start and finish lines, which are hard wired to a fairly simple timing box with multiple time displays that can track 2 or more (typically 4) times simultaneously (which also limits how many vehicles can be on course at once), with the oldest time being replaced by the newest time, so timing integrity is not dependent on the PC, but on the "simpler" hardware inside the t
  • by Spiked_Three (626260) on Friday October 28, 2011 @09:36PM (#37876082)
    I have been working on a racing timing system for RC; [] is an older screenshot, but you get the idea. In my research I came across this; [] which does recognize based on imagery. Your idea certainly seems feasible. for RC, we just byte the bullet and use the expensive MyLaps (AMB) transponder system ($3000 base + $125 per transponder). I assume they have some huge patent on it because it seems like it would easy and cheap to copy, yet no one has done it. Good luck.
  • I think my cell phone can do this already

  • The problem with magnetic stickers is... Corvettes have fiberglass body panels. :-)

    I once ran timing, here are my thoughts:

    Personally, I don't think that transponders are expensive, and I think they'd be a great solution which would absolutely fail because of politics. "You mean I have to buy a $100 device (or rent for $5/event) to mount to my $40,000 car that has $2,000 rims and $1,400 tires?!? What do you think I am, made of money?!?"

    I suspect you won't be able to do good detection except if the

  • QR codes are the right idea. The real money you'll need to spend is on the camera and near-realtime PC to process it.

    I've had good luck using GigEVision under Linux. There's a bunch of vendors out there that have Linux drivers for their GigEVision cameras and the specialized acquisition hardware is just an ethernet card. You probably want something that goes at least 30 fps sustained (probably about 1-3k for a camera, depending on resolution and bells and whistles). That's plenty enough to be able to int
  • by SEWilco (27983)
    The crucial data is the timing, while identification is a task. You must record the timing, but it is not crucial to perform the identification in real time, is it? You just need to be able to eventually produce the timed list. Record the timing and photo information in a way which lets you later review and compare both, so if you miss an identification it can be done later.

    Yes, try to do the identification task immediately, but ensure that the system has the needed abilities to deal with problems. Ra

  • Identify unique shape, numbers, barcode, qr code or similar in the images, that have been attached using a magnet to the vehicle's door.

    Not all vehicles are steel. Magnets might not hold your barcode on all vehicles.

  • Find me someone intimately familiar with an Android phone, or barcodes, or RFID, who can also grok basic SQL, and somone intimately familiar with the particular practical difficulties of SCCA timing, and I'll have your solution in-place, tested and working, before lunch.

    This isn't rocket surgery.

    (And if you give us until supper, it might even have a fancy web interface.)

    • I'm your Huckleberry.

      Cat got your tongue? Don't want to spill the beans?
      Why not outline some basics of your design and we'll help identify where the weaknesses are. Cause there's a HUGE hole there right now...

  • How about a big QR code on each door and a camera hooked up to a laptop at the way-points?

  • I can think of three options:
    1) Expensive, but available immediately:
    There is license plate reading software in use on highways in Europe. These turnpike systems use cameras to read the license plates and LIDAR 3D laser scanners to reliably measure the size of a truck. The lase information should provide very reliable timing data, but likely are an overkill.
    As others suggested special markers on the cars could be easier to identify then license plates.

    2) cheaper in development but higher material cost for e

  • I would couple the beams with RFID tag (tag identifies the car, while the beams do all the timing). I would also suggest maybe getting together with another club and sharing the gear or a local university (with this one could probably get them to help make up a good system). As long as you choose separate race days. I'd also imagine quick setup and dismantle is needed?
  • Get two line lasers. Modulate the beams at 20kHz for the start beam and 22kHz for the finish line beam. Direct the beams from overhead down to the start/finish lines. Design a timer/detector (I'll volunteer whenever I have time!) whose receptor is at least 1 inch in length and mount that to the top of each car. Each detector also has a small radio transmitter and a unique ID code.

    When the car passes under the start beam the timer is started and is stopped when under the stop beam. At the stop beam the tr
  • So many things missing from the OP's requirements like:

    Must work in ALL weather conditions (fog, rain, snow, dust)
    Must be accurate to 1 ms
    Must identify which DRIVER is in the car as more than one person may be driving any given car, and drivers may have full face helmets
    Must handle backward/spinning/sliding finishes
    Must process in near realtime ( 20sec between finishes)
    Must handle multiple cars on course at once (at least 3 running)
    Must handle GoKarts and other strange pieces of machinery that may not have

  • I don't know how timing is normally done for auto races, but I've been part of the staff at a few track & field events, such as the Nike Indoor Nationals, and seen how the timing is done there. There's a special camera that captures a single column of pixels, carefully aligned with the finish line, that records a rapid sequence of images whenever something changes in its field of view. The software assembles all these one-pixel-wide images into a single image whose horizontal axis is time rather than

  • Several posts have objected to the frame rates of consumer video cameras as limiting resolution. However, this can be overcome.

    For one, there are high-speed cameras with much higher frame rates. They are quite costly, though, and not necessary for this applicaiton.

    I propose you use a multiple-exposure camera. Such things do exist in the digital world. Charge is allowed to accumulate for an extended period. You use a strobe to produce multiple images. You can use an infrared strobe to avoid disturbing partic

  • Contestants (be it cars, people whatever) have an RFID tag (probably passive, 900Mhz RFID) in a name tag or other tag (tag on dash of car) that will give you decent interval timing.

    For the finish line, or where timing is more critical, you can supplement with a camera (photo finish if you will).

    900Mhz RFID is typically good for 15+ feet (depending on the size of the tag) and can be used reliably up to about 45 feet (big tag on big metal object - like a rail car). Tags can be very cheap - about 25 cents. T

The moon is a planet just like the Earth, only it is even deader.