Carlson Survey 2014 Export to Google Earth

Here's a link to the Google Earth help page on coordinate systems.

https://support.google.com/earth/answer/148110?hl=en

Hope it helps.

I do this all the time. The only time I am off by that much is if my linework isn't hinged on something I have already surveyed. What information are you using to base your drawing on? Have you got any GPS observations on the job yet?

yeah the drawing is based on GPS shots and brought up to the ground.

I'm fairly certain that in Carlson 2014 and earlier, you'd need to physically scale your drawing content by your Scale Factor to account for Modified State Plane Coordinate Systems when outputting to Google Earth.

Starting with Carlson 2015, you should be able to apply the Project Scale Factor found under Settings -- Drawing Setup.

Some years of photographs on Google Earth overlay better than others. Try the timeline up top and flip back a few years. You may find a better overlay.

And, in my experience (Carlson Acad 2013 and Intellicad 2015), no need for scale factors. Just set your coordinate system right in drawing properties and go from there.

Kevin

> ... and brought up to the ground.

Seems like a silly question, but How?

The reason I ask:
I have an OPUS solution for a point. On Zone 1602 (KY South), so not too far from you:

Northing = 1827856.689

Combined Factor for this point =

0.99996946

Divide and we get

Northing = 1827912.513

Difference between the two = 55.82' (almost what you are seeing as error on the aerial panel)

So if someone gave you state plane coordinates that were reported now as ground, but the only thing they did was scale them - you may not be in the right spot with your coordinates. I have seen people report such a scaling of coordinates as SPC when they actually are not. Be wary of the data unless you have done all of the work on this yourself.

I agree with Kevin Young - "...no need for scale factors." If you are placing this over a Google image and just using a smartphone or resource grade receiver to look for corners, the difference between grid and ground will not matter at all. Just use the original state plane values and don't try to "correct" them to ground.

Well we have 3 points on the site that we have OPUS observations on. We took the average of all three combined scale factors for the points and scaled the control points up using the averaged combined factor. When I export the linework it falls NE of the correct location. Almost like it is scaled up twice.

The drawing setting is set at 1.000000.

I'll mess with more on Friday. Time to enjoy the evening.

this is why you do not "Scale" grid coordinates to ground. You scale distances not coordinates...Never scale coordinates.

Amen.

> this is why you do not "Scale" grid coordinates to ground.

Exactly.

From StLSurveyor's Wednesday, December 31, 2014, 17:49 post, he states that "When I export the linework it falls NE of the correct location."

That makes me wonder even more if this is not a case of scaling coordinates.

If I am thinking correctly, which is not always the case:

If you had a group of points in a drawing file and scaled them "up" (I'm thinking that means scale factor > 1), and held 0,0,0 as the base point. All of the new points would fall NE of the correct state plane coordinates.

My typical workflow is to observe two points with GPS and turn them into OPUS. The ground coordinates provided from OPUS in from a combined factor. I then take the OPUS ground coordinates and key them into the data collector and go to work with a scale factor of 1.000000000 in the data collector.

The line work drafted from these ground coordinates was exported from Carlson into Google Earth and it landed NE of the real location. When I exported the dwg using Carlson's KMZ export the drawing setting scale was 1.0000000, in the correct zone and coordinate system.

Perhaps I am doing it all wrong? That why I posted the error here.

OPUS doesnt provide ground coordinates..it provides grid coordinates..how are you getting "ground coordinates"? how big are the sites you are working on here?

By multiplying the grid coordinates by the combine scale factor in the OPUS report.

Maybe two miles - typical.

that is the problem..You never apply the CSF to coordinates, it shifts the points. instead hold one grid coordinate as fixed and multiply the CSF by the distance between that and your second point..then use that distance and your azimuth to calculate the coordinates of your second point.. then proceed as usual. This is still not great procedure, but should suffice based on your current workflow. You would be much better off working in an LDP..

based on that distance, I would think that you will need to tighten up these procedures. There are several approaches depending on a number of factors. The simplest might be to enter the average site combined scale factor in your total stations data collector (not the GPS) and record everything as grid measurements. You can then use software and the inverse of the CSV to report ground distances. My way is to create an LDP and record everything as ground and use the software to calculate coordinates. if the elevation changes drastically over the 2 miles, it is best to use the first method.

Interesting. MoDOT will typically provide a CSF and scale all control about 0,0,0 to get the the "ground".....

Not long ago, there was a very long (but beneficial) post about "modified state plane coordinates". It has some excellent information about the DOT procedures in place around many states as well as discussion about how that relates to state plane coordinates, ground distances, and a finite point on the earth. Might be worth looking up when you have time.

When doing your DOT work, you will still use the methods they employ - scaling coordinates about the origin.

However, for your current issue -
When you multiply the coordinate by your scale factor, each coordinate is moving to a different location. That is why you are seeing the shift to the northeast - each coordinate is getting a larger value, so they move to the NE (larger northing and larger easting).

As rambleon has pointed out, the scaling should be properly applied to the distances between points.

One quick fix is to translate your project back to one of the OPUS coordinate values. That will have you back in the 'right' location for overlaying on the aerial. Just be careful of providing any coordinate values outside of your office as others might think they are looking at state plane coordinates when they are not.

I have not done much work with DOT's so I did not know this was a common practice for them. I doubt that changing DOT's methods is likely given government mindset but if you need to georeference anything with their ground coordinates, i suggest you just scale their coordinates back to grid.