Emlid Flow and US State Plane Coordinates

[hydrokiwi]

The ability to use FLOW in local coordinate systems is great - however there is a problem with US State Plane Coordinates.

The feet option is in International Feet not US Survey feet. States like California use US Survey feet in their local coordinate systems.

A U.S. survey foot is expressed as a fraction — 1200/3937 meters — while an international foot is expressed as a decimal, exactly 0.3048 meters. This is a small difference however, with seven digit coordinate values it makes quite a difference. About 20 feet in my case.

One solution would be to add US Survey feet in the units dialog . Right now there are only meters and feet (I believe to be international feet). And yes - I do wish we were in the metric system - it would make life easier.

The other option would be to give EPSG numbers for the coordinate systems in the Library and provide the correct combinations of horizontal datums and units. . As you probably know these codes can be found at spatialreference.org.

Thanks for the great work on the app. It helps a lot.

Cheers
John

[Zaz5400 (Zaz Villanueva)]

I can confirm that flow has usft, as I use it all the time. Also, nationally the US is moving away from the US survey foot in favor of one foot, the International foot. See here from NIST: U.S. Survey Foot. That being said, most surveyors in the US will continue to use what their respective state has adopted according to the NGS: https://geodesy.noaa.gov/SPCS/images/spcs83-legislation-feet.png. Also, there is a USFT option for CA zones in state plane NAD83 2011. See attached.

Lastly, I would recommend www.epsg.io over spatialreference.org. I used to use special reference, but definitely prefer the former.

[hydrokiwi]

Zaz:

Thanks. Yes I see the option shows up in the Android version of Emlid Flow but not on the Web version.

I used the web version in the office to prepare my project for stakeout - hence the problem. The coordinates from the Autocad file were in US_ft but the Web version only offers meters or feet which introduced a significant stakeout error.

So it would be good if the web version can be updated.

Thanks for the update on the use of Survey foot. It makes sense. Most of the legacy drawings I work with are US Survey feet either NAD27 or NAD83 horizontal datum.

Cheers
John

[Zaz5400 (Zaz Villanueva)]

Understood. It also shows up in the iOS version of the app. I have never tried the web version. I should check it out!

[hydrokiwi]

Dear Emlid:

Please can you update the web version of Flow with the same set of projections that you have in the Android and IOS versions.

I appreciate your help.

Cheers
John

[michaelL (Michael Lambert)]

USft is in everything that I have used in Texas. What EPSG are you using? The USft has been officially deprecated since January 1st so hopefully our work in Land Dev and Construction will weed it out pretty quick. I know we are using it for any more asbuilts…

[adam.nako]

@Emlid…I second the request from @hydrokiwi to enable the same options on FLOW 360 as is available on the apps. I ran into this same issue this week.

[julia.shestakova]

Hey guys,

Sorry for the late comments.

That’s a good point. Thank you for bringing it up! I’m checking it with the team. And I’ll keep you posted on the updates about it.

[julia.shestakova]

Hi there,

Just wanted to let you know that we have registered it as a feature request for Emlid Flow 360. If I have any news on it, I’ll post them here.

As a current workaround, you can create new projects using Emlid Flow. You can select US feet there, so it should be fine.

[kseniia.suzdaltseva]

Hi guys,

US Survey Feet is now available in Emlid Flow 360. If you have any feedback about working with it, let us know!

[michaelL (Michael Lambert)]

Woohoo! Thank you!