Firstly, as I mentioned previously, I don't believe it is possible to overlay a dynamic image in the way you are talking about. The device itself is using vector graphics that are hard coded into the device, the map data does not contain any graphics.
Vector data could be provided.
Secondly, bandwidth is still an issue. You will have to stream coordinate information from the device, to your remote server, which can then return an appropriate segment of your precipitation image. This will result in a near-constant 2-way traffic.
Not if the slice of data provided is large enough to cover your trek for the next 10 minutes or so, which I really don't think would be a problem at all. We should be talking about very small file sizes for such a small area.
You have to consider the CPU cost (to the TT) of both receiving that data over BT and rendering it (if that is possible). Even a normal traffic data update (only a few k max) slows down the device noticeably.
I've got no counter attack for that one. Certainly sounds like a problem.
You will also not be able to use your phone for calls at the same time.
Probably true, but I wouldn't invision more than a few second update at most every 5 minutes. I know in CMDA EVDO areas an incoming call can kick you off of the internet and come through. This is not possible in CMDA 1xRTT, but most metro areas are EVDO now anyway, as are a lot of rural areas. Not sure about GSM technology.
Thirdly, how would you display such an image? The TT's '3D' road-ahead view is extremely limited, extending at maximum to only a kilometer or so, even at highway speeds (it is always less than your view through the windscreen). Top-down 2D view is equally limited. You can zoom out, but it automatically zooms back in. There is no way to stop that AFAIK.
This is probably the biggest problem I'm hearing. I actually just purchased the TT One LE from Best Buy today, and have just been playing with it over the past few hours. With my Garmin I could zoom out as far as I wanted (incidentally Garmin does have an XM radar data feed you can subscribe to that displays on the Garmin -- so there definately is a demand for this -- as with anything, there is a certain group thats interested). I would say you'd need to be able to zoom out to at least a 30 mile range for it to be remotely useable/interesting, and if that isn't a function you can do then it's a moot point. However, I see you can 'Browse' and get a much larger view of a state or more, which would be in line of what you'd need for this. So perhaps those zoom levels could be tapped into in code.
TT, do not provide radar imagery with their weather service, probably because for most people it is entirely useless. You have a better view of upcoming rainclouds through the windscreen.
I'll tell you from storm chasing here in the U.S. for 13 years that what you see out the window is not always what you're going to get. You use words like Windscreen and Kilometers, so I'm guessing you're not from the US originally. Our weather here is much more volitale than in the UK and there's a lot more to it than just slippery roads and a little thunderstorm. However, I will admit that if I wasn't a storm chaser, I would rarely run into anything that I would be concerned with on a regular basis to pay for such a service.
Icy roads are shown as an ice crystal in a red warning triangle on the road.
Cool, I was wondering about that. That should come in handy here in Minnesota. We're getting our first accumulating snow tonight FYI.
Did you look at the Opentom project yet? There is no point in re-inventing the wheel. Let us know how your project progresses.
Yes, I glanced at it. I didn't get too involved as I wanted to think it through, talk to you and look at the device first.
I think given the information you've enlightened me with along with my own priorities and challenges with this project, I think I'll put it on the backburner and probably never attempt it. But I wouldn't be surprised to see TomTom partner with someone to provide this service in the future, as Garmin already is a step ahead in that feature.
But I must say... I'm thrilled with my One LE. I think the switchover from Garmin to TomTom is the right choice and I am LOVING what I'm seeing so far... and I will subscribe to the Traffic/Road Conditions/Weather feed.
Regards,
Andrew Revering