Jezz it would be nice to have a live video feed streaming like the PWA. They may need to do it next year.
Agreed choco. Anders now on par with A2 both on 51.34!!! Lenna 45+ too! CB now over 50 as well!
Read somewhere dunky is arriving on the 20th. A2 may have just lifted the bar again!!
Haha I'm studing Facebook quite hard. Looking through comments and a few other Facebook pages I have liked. Past my bed time now though..
, Hardie maybe Izaac is a "Indigo child"
Results from today www.redsurfbus.com/2012/11/luderitz-faster-and-more-furious.html
Love to see someone now plug in the original windsurfer one design board to crack 40 on it would be great recognition for the board that started it all.
A2s 2 sec was 53.42 average 52.05 500m 51.88 thought he would have gone faster
gee the run looks sweet as
Choco I'm sure Jim Drake would be proud coming from a background of speed, but I think the triangular sail would hold us back.
It depends if they're recording interlaced or progressive. If they're recording on fields, they will be getting 50 fields per second and doubling their accuracy.
But surely they can use a bit of interpolation to get better than 0.04 of a second? At 50 knots they'll go a metre in a 25th of a second. If the video has a sailor about .4 of a metre before the start line at say 9.0 sec and about 0.6 of a metre past the start line in the next frame at 9.04 seconds, wouldn't you say he crossed at 9+ 0.4*0.04 = 9.016 seconds? I'd reckon by carefully examining each frame they should be able to estimate position to a tenth of a metre and get 0.004sec resolution or 0.011 knots.
I learned yetsterday they're using software created by Manfred Fuchs, which is approved by the WSSRC. This software uses the last image before the starting line and the next image after the starting line. Markers are set on the front of the mast base in the images and on the starting line itself and the software interpolates the positions of the mast base to know exactly when the rider passed the line. This can be done since you know the interval between two images and that the speed of the rider will not vary by too much between the images, which I think they'll have figured a worst case scenario out for.
Do the same again for the finish line and you can pretty accurately calculate the time it took from start to finish.
The only factors that would influence this are the viewing angle of the lenses used, the distance to the rider and the horizontal resolution, but I'm sure they can find a worst case scenario there and subtract it from the result just to be sure. That would still make a 25Hz PAL system pretty darn accurate.
Thanks dBA. That's very good to know. If Manfred had a hand in it I have full confidence that it will be very well thought out and very accurate.
It is my understanding WSSRC required accuracy to at least 10cm for the Trimble GPS system that MI used, so that explanation makes perfect sense.
Except....isn't the course supposed to be 501 meters?
[}:)]
From the few tracks I have seen so far where we can compare 2 x GT31 GPS and fixed gates, the difference seems smaller than I had expected. It certainly reinforces that The WGPSSRC method of error correction we use at the moment is quite conservative.
anyone??
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