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Joined: Aug 31, 2005 Posts: 15137 Location: Bradford, West Yorkshire
Posted: Mon Nov 27, 2006 4:50 pm Post subject:
Privateer wrote:
I’m not familiar with the Mio GPS units, how do they do this? Is the information given in degrees or more helpfully "This Side", "Other Side", or "Reversible"? If it’s the latter, can you configure the Mio to only warn for just "This Side" or "Reversible" or Warn for all directions? This would be useful to verify the data even if a camera site is on the "Other Side".
Joined: 30/12/2002 17:36:20 Posts: 4912 Location: Oxfordshire, England, UK
Posted: Mon Nov 27, 2006 6:27 pm Post subject:
MaFt wrote:
you've probably already found this though...
Thanks for the link. I searched several of Sallyann’s posts but I missed that one!
Sallyann, OK you can display cameras:
1. In your driving direction.
2. which are two-way, i.e. reversible.3
3. Unknown direction.
There is a 4th display that I would like to see as a user configurable option and that’s cameras on the opposite direction to your current driving direction. Do you know if this is possible on the Mio? This would allow Mio users to be camera spotters and ensure that the camera was valid even if it was for the opposite direction and therefore not a threat to their current driving direction.
Another question for Sallyann: Do you know what the angle of acceptable variance is on the Mio for directional cameras? If you’re heading due west (i.e. 270) how many degrees either side of that will the Mio software detect and display the camera's direction?
A further question for Sallyann: How does the Mio software display of directional cameras, cope when you approach a (say) 90 degree bend with a camera that has directional data immediately after the bend? Does the software correctly show the correct direction of the camera? I'm guessing that it would even at the initial warning when you might be travelling for a short while in a different direction to the camera.
Sorry for the questions – I’m just interested in the use of directional camera data.
Regards, _________________ Robert.
iPhone 6s Plus, iOS 14.0.1: iOS CamerAlert v2.0.7
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There is a 4th display that I would like to see as a user configurable option and that's cameras on the opposite direction to your current driving direction. Do you know if this is possible on the Mio? This would allow Mio users to be camera spotters and ensure that the camera was valid even if it was for the opposite direction and therefore not a threat to their current driving direction.
All cameras are shown as icons on the map, so if you notice a camera across the road you can look on the Mio display and see if it's recorded (if you can take your eyes off the road!). If the direction is recorded correctly then it won't give a visual or audible alarm. If it's shown as an omni then it will alarm. I don't know of any way to over-ride the direction setting and give an alarm in every case - this would of course defeat the purpose of the direction info.
Privateer wrote:
Do you know what the angle of acceptable variance is on the Mio for directional cameras? If you're heading due west (i.e. 270) how many degrees either side of that will the Mio software detect and display the camera's direction?
I don't know, and I don't think Mio will tell you since they never answer questions about the software. However I can tell you this from experience: there is a traffic-light controlled cross roads in west London which has a camera looking forward at the traffic approaching on just one of the roads. With the imported database an alarm is given by the GPS if you approach the junction on any of the roads, which is annoying. Since I have started adding the direction info for this camera to the imported database, it only alarms on the one road where the camera is mounted.
Privateer wrote:
How does the Mio software display of directional cameras, cope when you approach a (say) 90 degree bend with a camera that has directional data immediately after the bend? Does the software correctly show the correct direction of the camera? I'm guessing that it would even at the initial warning when you might be travelling for a short while in a different direction to the camera.
I can't answer that because I don't recall approaching a camera mounted as you describe.
Remember that the only directional data we have at the moment to base any tests on are the limited ones that individual users have entered themselves. The Mio-provided database does have directional data for some cameras, but since it is very inaccurate most users posting here will have given it up to use the PGPSW database. If the directional data could be provided for even a small proportion of cameras we can start giving feedback on how well it works. It will also encourage other manufacturers to include a similar facility, so you will be doing the entire community a service.
I wonder if the is anything that the rest of the Mio community could do to help. I was wondering if all Mio users could update the cameras on their own units for there own little geography and upload it to PGPSW so that it could be collated. That would make a start.
I'm not sure if the format would support the directional flag though maybe thats a question for Sally.
I wonder if the is anything that the rest of the Mio community could do to help. I was wondering if all Mio users could update the cameras on their own units for there own little geography and upload it to PGPSW so that it could be collated. That would make a start.
I'm not sure if the format would support the directional flag though maybe thats a question for Sally.
I'll do what I can to help though.
Dee
Thanks Dee. The standard submission screen already has a 'direction' box, and I hope that this has been used by people submitting new or revised cameras. It doesn't have a separate box to enter whether it's a one-way or two-way camera, but when I have submitted changes I have put the extra information in the description box. If you have any direction info you could always submit it this way.
I believe that the database guys have been working on this issue, so it's probably best if we continue using the same method until we know how they are going to proceed.
M8TJT has been carrying out some very useful tests using directional data on his Mio, which may be of interest to Privateer and others. I've noted his comments below:
M8TJT wrote:
I first did a drive at about 45 - 50 MPH over a straight road. This road passes through 0.36576E, 50.83803N and recorded the trip using the GPSGate NMEA recorder. I then played back the recording into GPSDash to establish that the eastbound track of the road is 217 Deg (True from GPS). I then placed a 0.36576,50.83803,"GATSO:3@30",217,1 in the Pocketgps_Uk_SC.asc file, recompiled the .MTC file using your program and copied it into my Mio.
I then ran the sim through to MioMap which alarmed at 485yds.
I repeated the process using different camera 'headings' and found that I still got the alarm at 485yds with the camera +-40 degs off track, (257 deg and 177 deg), but with an 'offset' of +-45Degrees there was no alarm, indicating that the acceptance angle is somewhere between +-40 to +-45 degrees. This of course is for a straight road approaching the camera head on.
So it seems like the accuracy of the camera azimuth that anyone puts in must be better than 40 degrees to ensure that the camera alarms on the Mio.
Set to omni, my 'camera' still pings at 485 yds.
.......
I have a redlight camera close to me at the end of a short 150yd straight after a 30/40deg r/h bend. As I approach it round the bend, it first alarms for about a second at 480yd, then goes quiet, alarms again at 280 then goes quiet and finally alarms and stays on at 190 when I am on the straight approaching it.
I want to try offsetting the angle by about -20 deg to point it at 197 instead of 217 so that its back is facing the direction of approach.
This is excellent piece of work by Trevor. I've not had the opportunity to do such comprehensive tests, but I have edited cameras on a dual carriageway that I use regularly, to make them look only in the one direction. It's good not to be constantly troubled by cameras on the other carriageway. Also I created an imaginary camera on an overbridge and set it to look both ways. There was no alarm when driving underneath.
What we need now is for PGPSW to release the directional data for cameras where it is available, so that those of us with Mio's can see how it works in practice.
Sal
PS I hope I have accurately combined Trevor's various notes. If not, I'm sure he will pop up and correct me.
Joined: Apr 04, 2006 Posts: 10118 Location: Bexhill, South Sussex, UK
Posted: Tue Dec 05, 2006 9:14 pm Post subject:
Sal
Thats Ok. I still have to do some more experiments on cameras on bends (my favorite redlight), and will publish these as soon as I have the facts together. I don't want to go off 'half cocked' and publish duff gen.
Trevor
Joined: Apr 04, 2006 Posts: 10118 Location: Bexhill, South Sussex, UK
Posted: Thu Dec 07, 2006 11:37 am Post subject: MioMap Camera Directions
Mio Map 3.2 and Speed Camera Detection
By M8TJT 07/11/06 Introduction
Having just bought a Mio P550 and MioMap 3.2, I decided to do some checks to find out everything there is to know about the speed camera detection built in to MioMap and to answer the question posed by Privateer ‘Can speed cameras hide round corners’
I soon found out that MioMap would only alarm if I was driving towards a camera, and went silent immediately I when past it, indicating that there must be some sort of relationship between the direction of travel and angle of the camera to the direction of travel builtinto the Mio software. This was obviously less than 90o as indicated by the previous sentence.
Problem 1, find this ‘acceptance’ angle built into the basic Mio software.
I also found that if the camera were allocated a direction in MioMap, this would suppress alarms from cameras ‘on the other side of the road’ or pointing left or right at crossroads. So I also wanted to find the maximum error allowed on the speed camera direction before MioMap refused to alarm.
Problem 2, find th maximum allowable angle of camera direction error before MioMap fails to alarm.
Terms Used
I have used several terms that have specific meanings in the context of this report, so it seems reasonable to explain them.
Azimuth (az.): This is the angle between one point and another with respect to North, in degrees in a clockwise direction. I use True North in this report but azimuth can also be with respect to Magnetic North.
Angle off: This is the angle between two azimuths. The reference azimuth must be stated.
Bearing: Same as azimuth unless another reference is stated, such as ‘bearing 10 deg off the bow’.
Track: The path of the vehicle across the earth. An azimuth can be added to the track to define its direction.
Heading: This is the direction with respect to North in which the vehicle is pointing. This is not necessarily the same as track az., as the vehicle, especially aeroplanes and boats, may be subjected to side winds/tides, which means to maintain a certain track, the heading may have to be several degrees off track. Fortunately cars do not suffer too much from this unless you are a driftmaster or a Top Gear presenter.
Direction of Travel: Instantaneous track azimuth.
Method of Test
Firstly I drove along a straight road (passing through 50.83803N 0.36576E for those of you who want to follow this on your satnav) at about 50mph, recording the NMEA output from my satnav receiver using that wonderful piece of software, GPSGate from Franson. Having the journey safely recorded, I went home and had a welcome cup of coffee and trimmed the recording down to just the bit that I wanted. My direction of travel was roughly SSW (actually 217.5deg as established by replaying the NMEA data into another wonderful piece of software, GPS Dash.)
To solve the first problem of MioMap’s basic acceptance angle, I ‘placed’ a camera first at 50.83803N 0.36576E at 30MPH and with Omni set in MioMap. I then ran my simulation to find out at what distance MioMap alarmed. This was found to be at about 480yds (about 50.84136N 0.36981E). I then progressively ‘moved’ the camera further from the road at more or less right angles to the original position (up and down the river, for those who are following this on their satnavs) until MioMap stopped alarming. I then calculated the az. of the camera from the point of first alarm and then subtracted this from the road az. This gave me the angle off the road az. MioMap no longer alarmed when this angle increased to about ±15 deg. Whilst I was moving the camera out, the first thing that I noticed was that MioMap stopped alarming as the angle between my track and the camera increased i.e. as I got closer to the offset camera. In all cases of alarm, it was at a distance of 480 to 490 yards from the camera.
To solve the second problem of maximum camera azimuth error, I again ‘placed’ a camera with ‘Omni’ set in MioMap and at 30MPH, on the road at 50.83803N 0.36576E. I then used SallyAnn’s excellent MTC Builder software from http://rapidshare.com/files/768191/Speedcams_builder_201.exe to set the azimuth of the camera progressively more off the road az. until MioMap no longer alarmed. This angle was found to be somewhere between ±40 deg (still alarms) and ±45 deg (no longer alarms).
Summary and Deductions
A. MioMap 3.2 first alarms at about 500yd from the camera (driving at 50MPH against a 30MPH Camera).
B. Cameras can ‘hide round bends’ if your approach angle to the camera is more than ±15 deg. to the az of the road at the camera point. Not much of a bend - straight roads are good.
C. If camera direction information is set into MioMap, this MUST be within about ±40 deg accuracy and MUST be the direction in which the vehicle has to travel to get zapped by the camera or MioMap will not alarm. I see a possible problem of contributors inadvertently supplying direction information 180 deg out.
D. It is much more likely that a camera will fail to alarm or alarm late because of the basic acceptance angle (B) than slightly inaccurate camera direction information (C)
Apologies
I apologise for the lengthly report, but I included the method in case anyone can see a 'fatal error' in my assumptions/method.
I make no apologies to the scientific/European readers for working in imperial measurements. In fact my calculations to find the distance and bearing of one point from another were done in nautical miles, as these fit in rather nicely with Lat/Lon in degrees, and then converted the results to yards. Multiply yards by 0.914 to convert to meters.
To get back on-topic, after M8TJT's excellent work to investigate the limits of directional data I have updated all the cameras on my Mio on routes that I regularly use, to remove the annoying spurious warnings of irrelevant cameras.
It's particularly useful at the many junctions where there is a redlight camera on only one of the roads. Now, instead of getting alarms when approaching the junction from any direction, I only get alerted on the one road monitored by the camera.
I have notified a few of these cameras, but it seems a waste of your time and mine to notify them all if the directions are already known. So I will hold off notifying any more until you can publish the data and we can see which cameras still need to be updated. [/hint]
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