Local Ground-Based Coordinate Projections

Thinking out aloud here.

I haven’t had a chance to play around with the custom projections as yet, however, I think it may be possible to now set up a Local Ground-Based Coordinate Projection, allowing for ground distances to be output from the Rover.

If I have known point on a site (or I take an RTK average) , and then calculate the combined scale factor for this location, which if I inverse, gives me a ‘ground scale factor’, that I can input into the custom projection data.

Can I then also set the false E and N to be offset so that my known points coordinates then match a local site eg. 5,000, 10,000?



When I saw that custom coordinate systems could be used now, thought Localization also??? But I’d rather Emlid create something simple and clean in ReachView3. Hopefully this is getting real close, as Localization really is a necessity.

@michaelL has been groveling since the beginning of time for this. ; )


Hi Tim,
That would be great too.
Localisation, where you take shots on known points and then get the GNSS to, ‘fit’ your project is a different process to essentially achieve the same result.
Both would be a bonus!


James, below is a good reference to review. What you are discussing is a low distortion mapping projection system for your area. I don’t see why it wouldn’t work.

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If only the Flat Earthers were right it would make survey so much easier.
But humans just have to plot square boxes on a sphere, because we can.


Thanks Bryan, I have read that one before. The example is a great one due to the change in elevation.
Projects I am working on are often only about 300m wide/long and are relatively flat.

The interface of the new custom projections is similar but different to other software such as TBC.
In TBC it asks for project location (lat/long), approx. height, ground scale factor (which it computes for you), and a northing/easting offset (other software just asks you what values for the northing/easting you would like for the point).

I second this request!

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Hi everyone,

It’s a really interesting feature you’re discussing here! Although, it’s more of a localization feature than the custom coordinate system feature we have in ReachView 3.

You can set up the custom coordinate system when you know the transformation parameters. Those are unknown to your local system. So, you can only pick them up as you’ve mentioned already. However, even if you find them yourself, we can’t be sure the points collected using those local systems will be precise.

The localization feature looks to be very handy for surveying for sure. We’ll think about the possible ways of implementing similar functionality in ReachView 3.


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