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#201 shimonko

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Posted 29 November 2019 - 10:19 AM

In my opinion, a simulator is basically a launch monitor.  It does a poor job of simulating the short game and putting.  Putting is all feel and I don't know how you can create that on a simulator.  From a number of videos I have seen on You Tube,  setting it to auto putt is quite common.  What about a shot from a greenside bunker  using a simulator.  Do you open up your clubface and your stance? 

Autoputt is common because the majority of simulators just can't handle putting well enough. However many golfers trivialize putting because it can make their score look bad, so they turn it off. We see golfers often try to make a round sound better than it was by saying things like "shot 2 over with three 3 putts", like the 2 over was actually better than that. It wasn't - it was 2 over. We even see this IRL in a certain country known for vanity handicaps, where generous gimmes are taken and cards submitted.

 

Certain launch monitors however handle putting and/or short game very well - even SkyTrak. They're not perfect, but they are believable and it just wouldn't feel like golf without them. It's very rare any of the hundreds of sim players in OGT ask about autoputting and we were quite glad when Flightscope and TM users were removed, as they did autoputt.

 

Bunkers - yeah, I open clubface and stance to get some loft and stopping power. It's not the same of course, but we're never going to replicate real conditions - even bunkers at different courses in different conditions vary radically.  I played two out of puddle in there on the weekend as that was preferable to dropping. But I get in one or two bunkers a round IRL so I can handle that. Putting and chipping though is nearly half the game.

 

Many putt on sim via calculation - they calculate the effective length due to elevation, have putting charts at different stimps to give them a speed they have to putt. I agree, that's not putting by feel.

 

Not for me - I roam around the putt like one would IRL and get a feel for the shot. I do take into account the indicated elevation as that's hard to see, but don't care about the indicated length. I putt remarkably well when I do it, and poorly when I don't. Sim putting can be done by feel.



#202 shimonko

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Posted 29 November 2019 - 10:25 AM

Couple of things just to note: regarding distances, i think im right in saying Silverleaf course is at around 2000ft ASL. I assume VG2 uses same thing as PG in that elevation of course will affect carry etc, so that might explain the increased distances seen? Also the 335 yard drive on top of the elevation was also 40ft down hill, and got quite a significant bounce. No doubt a good strike and if data to be believed ball speed up towards 170mph, which is impressive none the less but not beyond quite a high proportion of very very good amateur players, of which it appears he is/
The spin axis/shot shape thing i will agree looks suspect for sure, looking at the path and face to path data, id expect to be seeing A LOT more curvature on some of those ball flights, might be the camera mode hiding it it a bit, but think safe to assume hardware "limitations" are having an effect there for sure

I think what we seeing here is sidespin intially being ignored or approximated, then when enough samples and calculations have been done, the flight is corrected. You can see this in the minimap here midflight where the ball skips to the right - also mucking up the camera follow. (11min13sec in)
 



#203 Dropzone73

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Posted 29 November 2019 - 01:13 PM

The scorecard shows 6 birdies and 1 bogey, the first three hole scores are hidden. There was probably another bogey in the first three holes to net a -4 final score.

Scorecard says 66 and course' par is 72. He played front nine 34 and back nine 32. Scorecard also shows 7 birdies and one bogey.

Your mathematics and reasoning ability is impressive :D.


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#204 Dropzone73

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Posted 29 November 2019 - 01:22 PM

Chipping and putting on jnpg simulator is very good and a lot of fun when using Skytrak or GC2. Trackman has isssues with short putts. OGT Tour uses 4ft gimmes. Trackman Radar launch monitor does not measure spin axis when used in doors. It estimates it from estimated Club data plus other factors. Thats probably why most shots were straight.

"Trackman Radar launch monitor does not measure spin axis when used in doors. It estimates it from estimated Club data plus other factors."

Pathetic!

It's like OptiShot :lol:. Even a shitty player like me can play under par and hit over 300 meters drives.

What a great indoor simulation!


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#205 GolfGuy72_2000

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Posted 29 November 2019 - 02:25 PM

"Trackman Radar launch monitor does not measure spin axis when used in doors. It estimates it from estimated Club data plus other factors."

Pathetic!

It's like OptiShot :lol:. Even a shitty player like me can play under par and hit over 300 meters drives.

What a great indoor simulation!

And it's a $15k+ product! Maybe that's why they had to change the name from "Perfect" Golf for Trackman :)


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#206 jmk59

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Posted 29 November 2019 - 05:38 PM

I don't think Trackman can track spin-axis or spin loft - it calculates  both from the Path Vector and Face Vector that it does track.

Attached File  Path-to-Face.JPG   57.26KB   0 downloads

 

Edit - seems Trackman has improved it's tracking technique since the above.  Shimonko is more current in his assessment.

My vector assessment, above, does not take into account the "gear effect" from off-center hits.



#207 shimonko

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Posted 29 November 2019 - 10:12 PM

Artisticly they don't look like Trackman's annotations on that image.

Radar can determine spin-axis simply by looking at where the fastest part of the ball is. How accurately that can be done indoors with so little sampling space is really the question. The shift in flight seen where I linked above suggests it's trying to sample for as long as it can and correct the flight as it gets a better idea, without delaying the ball taking off. Club data can be used to improve spin axis but I highly suspect it's not used solely. 



#208 jmk59

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Posted 29 November 2019 - 11:45 PM

The annotations and math are mine - on top of a Trackman pic.

https://trackmangolf.com/

 

I read through what they track, and spin axis and spin loft are not included.  I also read that they use a proprietary algorithm for one of those quantities - I think it was for spin loft.  I have an older Trackman presentation I can send you ( too big to upload) that states the spin-axis is calculated.  Here's that page: 

Attached File  spin-axis.JPG   129.38KB   1 downloads

 

If I had to guess (I'm an engineer that uses these equations), I think they use the "close-up" radar to get the path and face vectors, attack angle, club speed, dynamic loft , ball speed,  ball spin, and launch angle and direction.  Spin loft and spin-axis are estimated for the initial launch conditions.  The 2nd radar tracks the ball in flight and makes corrections to the spin-axis and total spin (spin down decay).  How it does this is probably the proprietary part.

 

Edit - read the patent, below, for the current description of spin-axis and spin rates.



#209 jt83

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Posted 30 November 2019 - 06:01 AM

Yeah I know, I should talk..lol, I have 5 courses I'm working on and can't seem to finish any and I get bored quick when I work on them.

 

Which five Joe?



#210 shimonko

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Posted 30 November 2019 - 11:22 AM

@jmk - again older posts so it's hard to know how TM have advanced in this area, but it does seem like we're on the right track:
 

When indoors TrackMan determines the spinaxis from the short amount of ballflight combined with club data. This way of determining the spin axis is very good except for off center impacts with woods (note that it is only off center impact in the heel-toe dimension which is an issue). The way TrackMan determines the spin axis indoors does not take into account the gear-effect which affects spin axis.
Example (right hand): Say, you hit it on the toe-side, then the spin axis should be more negative (draw), but isn't indoors.
 
When outdoors, TrackMan determines the spin axis from the measured aerodynamics which is quite accurate.
 
Regards,
Andreas Willadsen
Engineer
TrackMan A/S
 
 
and from Fredrik:

Q: How does TrackMan measure ball spin, and can it detect spin axis?
A: TrackMan has a patent on how to measure the spin rate of a sports ball (incl. a golf ball) and also a patent on determining the spin axis. For in-depth knowledge about the methods used, I refer to the patent (search for “determination of spin parameters of a sports ball” on patents.google.com).
 
But the fundamental idea behind the spin rate measurement technique, is that a rotating ball will generate multiple speeds relative to a radar: the bottom of the ball will move away from the radar while the top of the ball will move towards the radar for back spin type of shot. The key of the invention is to realize that this creates a modulation of the radar signal that produces multiple harmonic sidebands in frequency spectrum.
 
By determining the equal spacing between these sidebands, the spin rate can be directly measured without knowing anything about ball size, spin axis orientation etc. This is why TrackMan has become the gold standard for measuring the spin rate of the golf ball.
 

And looking at the patent mentioned, it seems what I said about looking at the fastest part of the ball (along with the slowest part) is only used to determine the spin rate, not the spin axis as this would be lost in the frequency spectrum.  They are very careful to use the word 'measure' with spin rate only.



#211 jmk59

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Posted 30 November 2019 - 03:08 PM

Sounds like they have advanced the technique since the article I posted. The article was talking about the Trackman Pro (no date on the presentation, but pdf is 2013).

 

I tried looking at their patent, US-8,845,442 from their web page, but didn't find it.  I'll try Fredrik's suggestion.  Thanks.

 

 

Edit

 

OK - found the patent: https://patents.google.com/patent/US9645235B2/en.  Thier method is very clever from an engineering view.

 

Two unrelated topics come to mind.  Figure 5 shows a good example of the spin-down rate vs time, for what looks like a 7 Iron.  I've only come across very old theoretical models for spin-down.  I'm hoping there is a follow-on paper related to spin-down.

 

Figure 8 is a good representation of how to model wind in 2D only.  After talking to Andrew (2 years ago), PG's wind equations were set up based on 2D from what he sent me.  That's why wind seems overdone above 20 mph.  I sent him the proper 3D equations and my spin-down model, with the idea that they would make it into PG2.

 

Patent searches also seem to be the only way to find reliable Lift and Drag coefficients for modern golf balls (if you're interested in that sort of thing).

 

John

 


 


#212 Joe Habiger

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Posted 30 November 2019 - 03:54 PM

Which five Joe?

 

Windsong Farms a very private golf course build on a horse pasture

The Legends GC (most holes are already laid down)

The Quarry at Giants Ridge

Cragun's Resort courses (Bobby and Dutch - did them for another game)

A redo of Hazeltine most likely.


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#213 JCat04

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Posted 02 December 2019 - 04:09 PM

Perhaps the biggest thing I'm learning from reading this thread is that if I ever get into the market for a launch monitor, I should probably go with Skytrack or CG2 :o   It sounds like Trackman leaves most a bit wanting in the short and putting game.


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#214 shimonko

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Posted 02 December 2019 - 09:28 PM

I wouldn't read that from this thread. Spin axis affects short game and putting the least, and we were going on quite dated information because of the absense of anything more recent. People used to report that Trackman struggled with short chips and putts, but I've seen at least one user very happy with the latest performance here. Here's a vid of him with a 6'7" downhill putt:


WnpnxWn.gif
 
Happiness is of course based on expectations though which is based on what you're used to - but it would be silly not to try things out for yourself given that lots of studios will likely be popping up soon with VG2.
You'll only get until Aug with a SkyTrak or GC2 anyway with JNPG, so it's TGC or FSX or the other lesser known titles.

#215 JCat04

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Posted 02 December 2019 - 10:22 PM

Thanks for linking that video of the short putt Shimonko.  I wouldn't have thought anything like that was possible with Trackman, based on what I've been reading.  It looked pretty natural to me!


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#216 zmax - sim

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Posted 02 December 2019 - 11:24 PM

it was one guy.  Many have said short putting sucks.



#217 JCat04

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Posted 03 December 2019 - 03:22 PM

it was one guy.  Many have said short putting sucks.

 

Yeah, true... but one thing for sure; if I was going to drop $20,000 on a launch monitor, I'd have to test drive it myself as to how well it handled putting before I did.  I'd want one for the full tee to green experience, not just for a tee and approach shot training device.


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#218 Buck

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Posted 04 December 2019 - 08:47 PM

Despite the changes not being "huge" between PG1/VG1 and VG2, it does seem like the lighting is more vibrant and reflective of the situation.

 

i.e.  darker when it should be and more "sunny and bright" when the situation calls for it...just more range of "looks" overall, which is very nice.

 

Do you guys agree?

 

Video 1

 

Video 2

 

Video 3


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#219 Pappy

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Posted 05 December 2019 - 01:43 PM

Even tho I'm totally lost following this thread I find it most interesting! Don't know why!

Signed: Ex vacuum tube tech

THOUGHT: Most plan for their Vacation - but most do not plan for their Eternity!

Video       Introduction       My YouTube      The Return


#220 JCat04

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Posted 05 December 2019 - 03:39 PM

Despite the changes not being "huge" between PG1/VG1 and VG2, it does seem like the lighting is more vibrant and reflective of the situation.

 

i.e.  darker when it should be and more "sunny and bright" when the situation calls for it...just more range of "looks" overall, which is very nice.

 

Do you guys agree?

 

Video 1

 

Video 2

 

Video 3

 

I agree on all counts, and really... these aren't the best quality videos from which to judge the overall graphics quality, but they do convey the  light balance more realistically.


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