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Localization training video  

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Shawn Billings
(@shawn-billings)
1,000+ posts Registered

This video is specific to the Javad Triumph LS, but the fundamentals of a localization/calibration are universal. It's concerning that there are many among us using this technique and are ignorant of the mechanics that are taking place.

Localizations/calibrations do not rubber sheet anything. It's an affine transformation meaning that the proportions of both sets of coordinates remain unchanged. Only the translation, rotation and scale are changed. This is determined by a Helmert 7 parameter transformation.

This video reveals issues that can occur with any software when proper oversight is not employed.

[MEDIA=youtube]YaQwREYp0Fc[/MEDIA]

Shawn Billings, RPLS
Owner of Pendulum Surveying in East Texas
I also provide sales, support and training for Javad Triumph-LS RTK Systems

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Posted : November 14, 2017 5:18 am
MightyMoe
(@mightymoe)
5,000+ posts Registered

Well, I watched it, it's the same thing Trimble does for a calibration.

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Posted : November 14, 2017 8:33 am
Shawn Billings
(@shawn-billings)
1,000+ posts Registered

MightyMoe, post: 455438, member: 700 wrote: Well, I watched it, it's the same thing Trimble does for a calibration.

That's why I shared it here. I'm not familiar with the Trimble interface, but I suspect the tools are there to identify problems with a localization/calibration and to address them. There is a great deal of ignorance regarding these transformations yet many professionals are using them. What's even worse is that they are encouraging subordinates who are even more ignorant to use them. But there is hope, as ignorance is curable. I do think there are many occasions that localizations/calibrations are very useful tools. However, there is a lot going on and users need to be aware.

Shawn Billings, RPLS
Owner of Pendulum Surveying in East Texas
I also provide sales, support and training for Javad Triumph-LS RTK Systems

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Posted : November 14, 2017 8:46 am
Cameron Watson PLS
(@cameron-watson-pls)
100+ posts Registered

Same with Leica although I can't include pairs and not hold them to see how they compare when different combinations of other pairs are held. That feature is cool.

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Posted : November 14, 2017 8:48 am
MightyMoe
(@mightymoe)
5,000+ posts Registered

Shawn Billings, post: 455441, member: 6521 wrote: That's why I shared it here. I'm not familiar with the Trimble interface, but I suspect the tools are there to identify problems with a localization/calibration and to address them. There is a great deal of ignorance regarding these transformations yet many professionals are using them. What's even worse is that they are encouraging subordinates who are even more ignorant to use them. But there is hope, as ignorance is curable. I do think there are many occasions that localizations/calibrations are very useful tools. However, there is a lot going on and users need to be aware.

Using Trimble you can walk through and back out of using points, look at the residuals.

Basically it's the same process.

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Posted : November 14, 2017 9:16 am
Loyal
(@loyal)
2,500+ posts Registered

Good info (and presentation) Shawn.

Hopefully this will reduce the MISUse of calibrations/localizations, and improve the overall understanding of just what is going on behind the curtain.

Due to my avoidance of all things construction related, I don't have any need for these techniques, and find their use in Land Surveys (retracements), to be problematical at best. But I don't do residential subdivisions either, so my 2 bits isn't worth much.

Loyal

"Perilous to us all are the devices of an art deeper than we possess ourselves."
Gandalf, The Two Towers

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Posted : November 14, 2017 10:13 am
Shawn Billings
(@shawn-billings)
1,000+ posts Registered

MightyMoe, post: 455450, member: 700 wrote: Using Trimble you can walk through and back out of using points, look at the residuals.

Basically it's the same process.

I'm sure Trimble provides more than just residuals. As I mentioned several times in the video, residuals do not tell the whole story. You have to evaluate the actual parameters and make sure they are realistic.

Shawn Billings, RPLS
Owner of Pendulum Surveying in East Texas
I also provide sales, support and training for Javad Triumph-LS RTK Systems

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Posted : November 14, 2017 10:47 am
MightyMoe
(@mightymoe)
5,000+ posts Registered

Shawn Billings, post: 455470, member: 6521 wrote: I'm sure Trimble provides more than just residuals. As I mentioned several times in the video, residuals do not tell the whole story. You have to evaluate the actual parameters and make sure they are realistic.

Yes, you can drill down in the data if you want, what I saw in the video basically confirmed my opinion that it's a thing to do only when there are no other options. I always thought "localization" was some kind of one step thing the way I've heard it described.

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Posted : November 14, 2017 11:00 am
MightyMoe
(@mightymoe)
5,000+ posts Registered

Loyal, post: 455464, member: 228 wrote: Good info (and presentation) Shawn.

Hopefully this will reduce the MISUse of calibrations/localizations, and improve the overall understanding of just what is going on behind the curtain.

Loyal

Loyal, I wouldn't count on it 😮

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Posted : November 14, 2017 11:02 am
Shawn Billings
(@shawn-billings)
1,000+ posts Registered

MightyMoe, post: 455475, member: 700 wrote: Yes, you can drill down in the data if you want, what I saw in the video basically confirmed my opinion that it's a thing to do only when there are no other options. I always thought "localization" was some kind of one step thing the way I've heard it described.

In my opinion there is no better method for determining the relationship between two static Cartesian coordinate systems than the Helmert 7 parameter transformation. Far better than holding a single point for translation and a second single point for rotation. With the 7 parameter transformation, each matching pair of points contributes to the overall solution.

Now, having said that, I also believe it is quite dangerous using Helmert 7 parameter transformations (call them localizations or calibrations) without a working knowledge of what is taking place. You shouldn't "drill down in the data if you want", you should "drill down in the data because you must". It's imperative for good, consistent results to evaluate the parameters. This is a main focus of the video (or at least that was the intent).

Shawn Billings, RPLS
Owner of Pendulum Surveying in East Texas
I also provide sales, support and training for Javad Triumph-LS RTK Systems

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Posted : November 14, 2017 11:59 am
MightyMoe
(@mightymoe)
5,000+ posts Registered

Shawn Billings, post: 455492, member: 6521 wrote: In my opinion there is no better method for determining the relationship between two static Cartesian coordinate systems than the Helmert 7 parameter transformation. Far better than holding a single point for translation and a second single point for rotation. With the 7 parameter transformation, each matching pair of points contributes to the overall solution.

Now, having said that, I also believe it is quite dangerous using Helmert 7 parameter transformations (call them localizations or calibrations) without a working knowledge of what is taking place. You shouldn't "drill down in the data if you want", you should "drill down in the data because you must". It's imperative for good, consistent results to evaluate the parameters. This is a main focus of the video (or at least that was the intent).

There were a number of things in the video that I found unsettling. He glossed over changing the numbers for the base point, why would he do that?

And because he didn't have very good elevation control he put a setting at 0 which he said would allow him to extend outside of his calibration with good elevations. Really?

I didn't understand that at all, is he saying he's attaching a geoid model to an elevation point, or is he saying he's making the rise over run 0?

Trimble used to have in their calibrations a ft/ft number (probably still do) to tilt their plane, of course a 0 would mean 0ft/1ft.
0 would not work well at all for that number, at least not where I am.

I went through the calibration wars back in the day, nothing is different now that I can see.
Using a Helmert 7 parameter transformation doesn't help when the base data is inferior.
Nor does LS make inferior superior.

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Posted : November 14, 2017 1:29 pm
Lee D
(@lee-d)
1,000+ posts Registered

The few times I've needed to do one of these I looked at all of the parameters of the transformation, but primarily the scale factor and the direction and percent grade of the vertical plane; I think those tell you more about the overall fit.

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Posted : November 14, 2017 1:33 pm
mattsib79
(@mattsib79)
250+ posts Registered

Shawn, I thought the video was well put together. I also think it will help future surveyors understand what is happening in the magic box (regardless of brand) so they can make informed decisions.

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Posted : November 15, 2017 12:39 pm
eddycreek
(@eddycreek)
500+ posts Registered

MightyMoe, post: 455515, member: 700 wrote: There were a number of things in the video that I found unsettling. He glossed over changing the numbers for the base point, why would he do that?

And because he didn't have very good elevation control he put a setting at 0 which he said would allow him to extend outside of his calibration with good elevations. Really?

I didn't understand that at all, is he saying he's attaching a geoid model to an elevation point, or is he saying he's making the rise over run 0?

Trimble used to have in their calibrations a ft/ft number (probably still do) to tilt their plane, of course a 0 would mean 0ft/1ft.
0 would not work well at all for that number, at least not where I am.

I went through the calibration wars back in the day, nothing is different now that I can see.
Using a Helmert 7 parameter transformation doesn't help when the base data is inferior.
Nor does LS make inferior superior.

I also missed the logic in that. The first thing the Trimble Sitech guys will tell you is to make sure your control extends past the limits of the site, make sure all of the points are good (relative to each other), and don't work outside of that.

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Posted : November 15, 2017 2:58 pm
leegreen
(@leegreen)
1,000+ posts Registered

Same process with Topcon Magnet Tools. Not sure why this is so eye oping to some.

Maybe old apps like TDs Pro Carlson can't do this?

~LeeGreen.com

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Posted : November 15, 2017 3:17 pm
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