I think the time has come to replace my Talex Lite. I think I'll look into buying a Road Angel Professional Connected and possibly keep the Talex unit in the cupboard until we have news on if it works or not with the PGPSW database.
Joined: 11/07/2002 14:36:40 Posts: 23699 Location: Hampshire, UK
Posted: Tue Jul 15, 2008 8:17 pm Post subject:
Our database admin who is liaising with the chap who is doing the work here is indisposed at present. I have no information so at present unless silentwol has an update you'll have to wait I'm afraid. _________________ Darren Griffin - Editor I ran the 2013 London Marathon in support of the National Autistic Society see here.
Last edited by Darren on Tue Jul 15, 2008 8:55 pm; edited 1 time in total
Hi, sorry for leaving you guys in limbo. I've been enjoying a bit of a break Also, the need for working on things that can earn money must take priority over hobbies ;)
Anyway, I've been thinking about this project on and off for a while. I've made no real progress since the beta release. What I have proved is that it is possible to get your own database running on the talex. Very little of the database format is now undocumented and what is left is easy to work out (e.g. what byte equals what camera type - all you need to do is drive up to a location, note the alert given by the talex and job done).
The problem is converting the PGSW database to to the talex way of doing things. Although the format is known (i.e. what bytes mean what - the way the data is organised and what it means), the way the talex works is quite different to the way the PGPSW detection works. It needs entirely different types of data. See previous posts by me which goes into more detail.
I tried to write a computer program that would read a map of Britain and do this conversion automatically. While this works quite well in rural areas and places with 'simple' road layouts, it easily gets confused around more built up areas (London!). This leaves me with a dilemma. Try and improve the program or give up. Sadly, I don't think I'm up to the challenge and even if I am, I certainly don't have enough time to work on it. It is a truely complex problem.
So, basically, I'm giving up on making an automated program to do the conversion. However, I think there is one last option left. If we can get enough people together, we can process the cameras by hand. We can use the program to give us a rough template... hopefully 50% or so of the cameras are converted properly by the program. We could have a system similar to PGPSW's with an online map that can have 'pointers' added to it and rotated into place. Thus anything the program misses or does incorrectly can be fixed by a human. I'd try and make it into a fairly streamlined process, so that it would hopefully take a minute or so per camera maximum, but the time still adds up. Last I remember, there were ~13000 cameras in the database. So if we could get 100 people doing 130 each, I think the task is fairly managable (two hours each). Once the database has been done, only new cameras need to be added, so this huge investment in time need only happen once.
The other option is that I write up everything I've found out and pass the baton onto someone else. However, I think somewhere down there line there is going to have to be a sizeable amount of human time spent checking any automatically converted database as the subject is just too risky to trust on something so fallible.
So, if people are willing to spend a bit of time working on this project, then I'm happy to help out Thoughts, commennts etc welcome
The talex has two sets of data (again, this is explained in a previous post, but I'll explain it here again).
Set1: Two points (i.e. long, lat and bearing) are placed 500 yards (or is it 400? I forget!) either side of the camera location (or as far as the raod will take you). So if you appraoch the camera from either direction you get a correct, early warning. This differs from the standard PGPSW implementation, which just has long, lat and bearing (and a flag saying it's bi-directional or not). Thus the tomtom makes an alert when you're within a certain radius of this location and optionally pointing in the right direction. (this is at least my understanding of the tomtom system).
Set2: Points are put (long, lat and bearing) at each juction that joins inbetween the above two points in Set1. he diagram below shows PGPSW data first, then Set1 data, then Set2 data). Small red points represent the actual data in each set and big red sploges show where I've drawn on the actual camera positions by hand)
So, as you pass over one of these points you get the warning "entering safety camera potection zone". Also, if you leave the road before coming to a gatso and pass one of these points in the opposite direction, the little timer thing will be removed and talex will give you the all clear.
So, in conclusion, Set1 is only two points per camera. These would be incredibly quick to do by hand and are pretty well placed by my program. We could really rocket though all these. Set2 however can have many points per camera, especially in places like London.
Why am I rambling on about this? The talex requires Set1, but NOT Set2. Without Set2 you don't get the "entering safety camera protection zone". Not a big deal in my opinion. Also, both the novus and talex databases don't include full Set2 data. In fact, I believe Novus stopped bothering with adding it entirely! This is not a hardware limitation, I think they just couldn't be bothered. I'm not sure about Talex as I don't have a subscription, but I'd supstect they're doing the same.
So, my suggestion is that we go through adding Set1 data, which wont take too much time and will get the PGPSW database running on your talex's. Then, once that's done, we can start work on the Set2 data where we feel it is appropriate.
Also, as an incentive, maybe PGPSW could give a year's subscription or something to anyone that makes say 300 submissions or more? Obviously this is up to PGPSW, but it might be a nice way of persuading people to help. I'd also like to point out that I think this way of having data (set1 and set2, compared to the PGPSW way) is a lot more robust (think less false positivies as you pass under bridges etc) and it might also be nice to try and implement these kinds of alerts on tomtoms too. So this data might not be resitrcted to just the talex. I'm not sure how tomtom works, but can you write plugins for it? I'd certainly be interested in writing one if other people aren't
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