# GPS tracking times

I have a GPS data on a closed road, where the cars riding laps, and I want to know how long takes to do 1 lap and also I want to add some points to calculate how long takes in specific sections. One of the main concerns is that the gps points never went for the same area, due to the gps accuracy. What you recommend me to do with this?

• How long are the road sections, and how precise do you want your timings? Nearest ten seconds, nearest millisecond? And importantly, what's the consequence of getting it wrong (or "how much do you care?")? Commented Jan 15, 2016 at 16:27
• Hello Spacedman, so the sections will be a bit random, the time accuracy at most would be seconds. But if you talking about from how far would be from my points, I would take the distance rather than the time from my preselected waypoints. My example for that could be one car following a close track and later on i would place some strategic points, depending how is the road features (no lots just 4 or 5) and also the direction will be always following clockwise direction. Commented Jan 15, 2016 at 16:42
• Please use the edit button beneath your question to revise it with any requested clarifications.
– PolyGeo
Commented Jan 18, 2016 at 11:00

I'd recommend to interpolate points on the finish line for all tracks/cars.

I'd use a simple linear interpolation, knowing this will also introduce more errors, depending on the track geometry around the finish line. See this example:

``````=========+======  >
A  +     B  >
=========+======  >
``````

Cars travel left to right. There are 8 segments between GPS point A and B. The finish line (`+`) is 2 segments away from A. Thus, the virtual GPS point on the finish line is at time

``````time(finish) = ( ( time(B) - time(A) ) / 8 ) * 2
``````