Circuit Overlays

[pmw]

Does anyone know if its possible to get hold of accurate circuit overlays which could be read into the analysis software for checking driving lines etc ?

Thanks

[Support]

not as far as I know... the only thing I can suggest is driving around the inside and outside of teh track and saving it as a run.

Support

[idol]

Molstly works, did some track mapping 6 month ago and the position accuracy is still acceptable, porbably about 1-2 metre off . So would be nice to set an offset manually on a "map" layer.....

[kapsopod]

When I load an older track layout run (that i have produced driving the inside & outside line of the track) and then I load 2 (or more) different laps from different runs, the software offsets a little bit the laps and in some places my driving line is outside the track I am not talking about the offset option which can be checked in the options. What I am talking about is happening automatically. I don't know why. The offset is small but still I can't compare my lines because they are not placed right compared to the track lines. I am using the latest version of the software since i downloaded it 3 days ago.

I do not know if it can be fixed or it is unavoidable.

[Turby]

The current GPS system is good for about 3 metre accuracy. To get better is going to cost lots of money. For more information read this report http://www.race-technology.com/WebPage2/Other/Articles/Technical%20assessment%20of%20DL2s%20GPS%20data%20quality%206.pdf

[Stan]

You also need to distinguish between absolute and relative accuracy.

[Support]

As has been mentioned, the problem is the accuracy of the basic GPS unit, it can drift around by a few metres, this drift can take a long time, so from one lap to the next the accuracy will look very good, but if you overlay sessions from different days you can easily get an offset. This is exactly why we don't make a bit thing about using the DL1 for driver line analysis. You can just about get away with it if you are lucky, but it's not really what it is designed for. If you do need much better positional accuracy you would need to go the 20Hz DL2 or ideally the the differential 20Hz version. It does get expensive though.

Martin

[Support]

As has been mentioned, the problem is the accuracy of the basic GPS unit, it can drift around by a few metres, this drift can take a long time, so from one lap to the next the accuracy will look very good, but if you overlay sessions from different days you can easily get an offset. This is exactly why we don't make a bit thing about using the DL1 for driver line analysis. You can just about get away with it if you are lucky, but it's not really what it is designed for. If you do need much better positional accuracy you would need to go the 20Hz DL2 or ideally the the differential 20Hz version. It does get expensive though.

Martin

[idol]

Or a software feature to correct the offset....

[pmw]

Thanks for all the replies. Does anyone know how amenable people are at trackdays for example to someone clinging to the inner and outer edges of the circuit for mapping purposes?

Also, if you drove around very slowly would that increase accuracy ?

[Turby]

Thanks for all the replies. Does anyone know how amenable people are at trackdays for example to someone clinging to the inner and outer edges of the circuit for mapping purposes?

You woul dhave to ask the individual organisers

Also, if you drove around very slowly would that increase accuracy ?

No, the inaccuracy is effectively built into the GPS signal decoders... unless you can get your hands on a military spec decoder chip

[jlucas]

I've gotten permission before at HPDE events to do it first thing in the morning. It's typically a matter of finding the right person to ask. They would usually much rather have you do a slow recon lap in a street car all by yourself than to be completely offline causing confusion during the regular run group. At a race weekend, I'm pretty sure you'll be SOL.