SkyTrak technical FAQ

[davray666]

The idea is to share some technical details about the unit that could be useful in order to figure out how to get the most out of it.
Here is what I have been able to gather (guess) so far.

Unit has 2 cameras and what looks like 2 Xenon flashes and 1 IR LED bank.
There are 2 additional sensor that are probably used to detect the ball launch and trig the camera image capture.
For each shot 3 images are captured. Time between images is
image 1 @ 0us, image 2 @ 4140us & image 3 at 10400us.

The rather long time between image 1 & 2 should produce good accuracy for vertical and horizontal lunch angles. I am more concerned with the spin numbers.
Would be interesting to see some comparison on high spinning shots against some other trusted unit. Especially really bad shots with lots of side spin (or spin axis tilt if we are to be correct)

In order for the unit to catch a high vertical launch angle shot, the ball needs to be placed in front of the red laser dot. The theory is that it will never make it to the second camera field of view if it's too far back.
I have tried with as much as 2". No idea how far it could be placed before it becomes a problem.

[davray666]

That is a good point but in this case it does not explain the inaccuracy.
Assume TM measures the VLA between the starting point and peak point, while ST measures it between the trig point and say 5" forward. Then the values would differ but the trajectory and carry could still be the same since the numbers do not represent the same thing. If that was the case then everything would be fine.
Problem is that the difference in VLA for high spin and low spin is not that high for a slow chip. That is because the lift force is proportional to spin and velocity.
This is very easy to test. If you have a Skytrak and some kind of screen that is not a mushy net. Then you can do some calculations and place some markings on your screen or ceiling that represent 35 - 60 degree VLA in say 2 degree increments.
Then you take your 58 degree wedge and fire of some shots and try to spin and launch them as equal as you can. When the ball hits the impact surface you will be able to see for most shots where it hit. If you marked the HLA in a similar fashion you can see that as well.
I have done the test and for the same shot type that has similar spin and VLA, the reported VLA and HLA differs a lot vs. actual. If you don't trust your self to see the impact point ask a friend to film it with a high speed cam like Iphone 6 or GoPro 4. Do 10 shots and tell us what you found.

I have done this with and without cameras and I can tell you that the HLA can be as much as 10 degrees off and VLA somewhere in the order of half that.
That Is why I have permanent markings on my screen so I can gaze the actual HLA and adjust the presented trajectory accordingly.
While a 10 degre HLA error is rare 4-5 degrees is common. On a 60 yards shot a 5 degree error is 15.7 ft wrong left/right.
If that is OK or not depends on who you are. For me that only use it for practice and can gaze the error I am OK since there's nothing better out there that I can afford.
For sim play where you can't correct it or do anything about it? Well it's still much better than Optishot so the same logic might apply. You know it's 5" from the flag even if the sim shows you it's in the water. Ignorance is bliss in some cases and I guess this is one of those.

[voodoo_ca]

Does anyone know how/if Skytrak is able to tell when a ball starts to the left or right of the target line?
Lets say a push - How does it know the ball is travelling on an angle based on the target line?
Something to do with the size of the ball in the camera shots?
Was just thinking about it and curious...

[davray666]

Yes ball size is used to determine left or right direction.

[TorchRedRob]

It's also important to note that typically, the right ball is bigger than the left ball.

[dsailer]

Do any of you know anything about Skytrak tracking slow chips? Since starting to play on WGT, I've noticed if you're just off the green and try to hit a slow chip, it won't register. I then tried the same thing with the Skytrak app with the same results. Since it CAN register puts, I'm assuming that this might be due to heuristics that weed out errant movement, and this being different for puts vs regular shots. WGT can be really frustrating if you're on the fringe of the green - you end up having to hammer way to hard and either fly across the green or maybe try to Phil Mickelson shot

[Tekbud]

Yep - this is a problem with e6 as well. I started a thread on it but no luck yet. Best I can do is a bump and run 8 iron that rolls about 20 feet on flat ground. That's the shortest I can hit one where it will register. Often times i have to kind of work up to that. Definitely frustrating.

[dsailer]

Yea, I don't understand why I can put WGT into put mode manually. Seems like something REALLY easy to do (and I've done iOS development).

The other thing that makes this worse is, if your short chip doesn't make it to the green, it literally sticks like Velcro. I've tested this a bit - you hit something like an 8 iron 8 feet (for real), on WGT it goes 2 feet and rolls about 6 inches. Between that and the not registering, it's downright evil.

On a positive note, I'm REALLY focused on hitting greens on approaches :0

[voodoo_ca]

I believe there are many other threads around relating to lighter chips and different simulations - E6 being one that comes to mind.

[Tekbud]

Does anyone know if WGT fixed the autoputt wack it by the hole 20-40 feet issue? I never heard back from WGT support after they closed my case saying that they had everything that they needed to resolve... I haven't played WGT in a while because of this so I have no idea if it's been fixed or not.

[doublebogey]

Not fixed. Still there. Frustrating as hell. Why not just give gimme instead of auto-whacking 40-50 feet past hole and off green?

[luv2golf]

That takes all the fun out of playing an ipad video game.