Caleb, That one has me stumped. Send screenshots to AiM. They were helpful. Send your inquiry to [email protected].
Larry
I had invested a significant amount of time getting comfortable with RS2. Once I saw how much more RS3 could do, I started over with it. Frustrating but IMO worth the change over.
It can do so much more than what I’m using it for, just need more time ( 
) to spend learning it/in the software using it.
Reggie. It’s worth the effort and the guys at AiM can support much better. I RR a FF which is probably closer to laydowns than laydown are to sprints. There are new dimensions to data provided such as GPS radius. The overlay functionality and being able to look at each section using satellite map. Have fun!!
The overlay is a neat party trick, but the GPS radius is usually so large that there are obvious errors showing you off track where you weren’t. For pin-pointing a racing line, it gives false confidence. There’s another thread that dove much deeper into it, but I’ve seen some pretty glaring inaccuracies in my own data
I found James Colborn’s series to be great!
I agree, which is a bigger problem with sprint karts tracks and less so on road racing tracks.
Okay, I see your point. James is driving on big tracks in auto-type race cars. I was still able to use most of his instructions for getting everything to work correctly but the data from a tight sprint track could be somewhat flawed?
Credit to AIM, I downloaded their latest version, and they seem to have fixed the bug I was dealing with. So, yay, it isn’t totally useless for me any more!
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Hi everyone, I wake up this post to give my penny about delta time, because before reading every single word of it I was losing my mind in RS3.
First case, an hairpin: in the green line I brake later, minimum speed on the apex is far better than the red line, then I’m faster also on exit. The result? half a tenth slower than the red line.
Second case, even more strange, another hairpin: the red line is always faster than the green, but according to RS the green was almost 2 tenths faster!
Yes, it’s possible that in both cases the slower line was little bit shorter but not too much, these are my 2 best microsectors in both cases among 200 laps and I’m pretty experienced driver so I’m sure that I take the apex in every line.
Please tell me what do you think about it, I need to know if I have to stop wasting lot of time in studying the delta times.
I believe your reference lap changed when you changed laps. If you switch back to the channels list from the laps list, you will be able to see which lap is the reference.
I have done a ton with the time compare in RS3 since before it was released. It is correct. What throws a lot of people off is that they got used to RS2s computation. A little aside on that - no two laps are exactly the same length. In RS2, the entire lap was shrunk or stretched to make the laps the same length for comparison. So take a slightly different line in T1 and make the length longer and the hole lap gets scaled a little bit down. This was the state of data when RS2 was written and what everyone did.
When RS3 was written ~20 years later, we have GPS, more powerful loggers, more powerful computers, etc. RS3 takes the lap and divides it into X number of segments, and then shrinks and or stretches the local areas to adjust the lap length. RaceStudio 3 Analysis — RaceStudio3 latest documentation This is much more accurate, but it throws people off in how it looks as they are used to the old way.
Sorry for the long answer.
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No apologize but thanks for the detailed answer. If you want, can you help me to understand better especially about the reference lap? Let’s take for example the second screenshot I posted: we have a microsector with hairpin + straight that the green line, the slowest one if we see the pure speed, covers in 5.650. Then we have the red line, faster, that covers it in more time, 5.813. Are these values real? Or should I do something (and what?) to normalize the values? Thank you very much
What distance does it show for each in the track split report when you select that segment?
I have 108.49 meters for the green and 112.73 for the red. The strange thing is that my average for this sector is about 111/112 meters, and I’m pretty sure that I didn’t cut the corner in the green line 
In my experience the time compare in RS3 is not always correct. I believe the issue with the RS3 “smart sync” is that it prioritizes the GPS position, but what happens if that GPS data is offset between two laps is incorrect due to GPS accuracy issues?
For the most part in karting we are driving the same lines pretty accurately as Jacopo mentioned, and it’s hard to have massive differences in the driven line especially when kart tracks can be relatively narrow compared to a car track.
I understand the differences in how RS2 and RS3 put together the laps together and align them, I do think RS3 does this better and the braking points typically line up okay without having to shift the lap like you need to frequently do in RS2. But I think it’s best to focus on the speed trace and use the general rule that prioritize higher minimum speed and exit speed.
For example look at this data, you can see a shift in the GPS data between two sessions. The GPS will say the apex of the corners weren’t hit, but in reality they are. The corners where the driven line is on the “inside” (example T1 red) will always show time gained, but on the other end of the track (T8 red) that same driven line is now on the outside of the corner (because of the GPS offset), you’ll see that corner as now “slower” regardless of the mid corner or exit speed. The RS3 time compare is only as good as the GPS data and at least in my experience on small kart tracks (compared to car tracks) it will have shifts even with a mychon5s. I would be curious if Jacopo showed the full GPS trace for his laps would you see a global offset.
That’s why I think it’s best to focus on the fundamentals: prioritize hard braking, minimum corner speed, and exit speed and compare that between laps/drivers than what the time compare says.
Thank you, this image is very clear about that. But now I’m wondering, so also the live gap on Mychron is not true? Because I think it’s based on GPS trace. Sometimes I see that, at one corner, the live gap increase or decrease too much, it may means that in the reference lap the GPS was incorrect?
Here the whole laps
Completely agree. I use RS3 to compare some different lines specially on hairpins, because depending on their radius sometimes is better to have a V line, sometimes is better to have late apex. But if RS3 is not accurate, in this way is totally useless
I want to make sure we’re on the same page, so I highlighted some parts of the lap. The left most is lap time, then the time in the segment, cursor time/distance, and then the time compare at the cursor position.
For selecting the reference lap, if you go to the channels tap, you can then set which lap is the reference. This can catch people out when the numbers get reversed and don’t seem to make sense.
Thanks for sharing, you can see on your GPS map there does appear to be a slight vertical shift from one lap to another and I would bet this is what is influencing the time compare result.
RS3 is much better than RS2. RS2 based solely on distance from start/finish. The errors were expanded through the lap and the GPS was not as accurate. GPS drift is different than accuracy. GPS accuracy is a pretty deep rabbit hole (I haven’t found the bottom). The drift can occur between sessions/days, but the accuracy of the data is the same as the drift moves all points the same. Everything is accurate but you will see the driven line offset.
If you want to know the accuracy of your session, check otu the GPS PosAccuracy measure (typically 1.5-2’ with the M5S) and the GPS Nsat (up to 16) which is number of satellites. If both of those are good, your data is good.
I think all racing on wheels has high accuracy when done well. The best drivers in cars are within 3" of driven line and things like brake points can be down to +/-30" at over 150 mph.
When you involve a map tile, you bring in another major variable. The map image is made up of multiple satellite images, often from different days/weeks/years, stitched together, and then projected flat. You can change the map tile and see the driven line go from perfect to offroad.
Overall the GPS is very accurate and is involved in every system and at the heart of the analysis of everyone that I’ve worked with from constructors to drivers. How they use it varies a little, but the driving fundamentals are always there.
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Great conversation to lurk on, great questions and examples of common and specific issues, and thanks Matt for helping to illuminate the nuances of viewing and comparing our data.
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I don’t have kart data I can share, so here is some of my car data with SC3 footage. Notice the lines are different, longitude is the same (track map is always North up), and the latitude is different by .0000134. You can see the difference in the video image too.
Working on this, I just learned something. The fifth decimal of a lat/long is worth about 1.8 feet, which looks around the difference in the video!
Hopefully this helps you out with the trust in the GPS. The programmers at AiM are way smarter than me and have much more experience in GPS than I do. Initially I too had data that didn’t seem to make sense, but I’ve gone through some of time compares that look off with high level motorsports engineers to always come out with RS3 being correct.
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