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Getting the wrong distances between survey points

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Message 1 of 8
brodymedhi
665 Views, 7 Replies

Getting the wrong distances between survey points

Hello, I am having problems with my survey points displaying the wrong length in distance in model space on autoCAD civil 3D. I imported the points through an excel sheet with northing and easting and the correct coordinate system and it is displayed correctly in the right spot when I turn on the aerial map. However, when I use a dimension or draw a line between two different points in my survey the distance isn't even close to being correct. When I click on the survey point it gives the correct latitude and longitude value as well. In the pictures it should be easier to see what I mean comparing distances between my model space in autocad and google earth. Are some of my settings incorrect? Am I importing them wrong? I am a student and don't have too much experience with civil 3D. Please Help!!google earth.pngautocad pic.png

7 REPLIES 7
Message 2 of 8
ChicagoLooper
in reply to: brodymedhi

Hello @brodymedhi 

There are two coordinate systems you must    take into account. 

  1. The coordinate system (CS) associated with your points. 
  2. The CS you assigned to your dtawing’s modelspace. 

<<Depending on what your points represent, e.g. utility poles, manholes, spot elevations, culvert start & end locations, etc., there are easy ways to input points ref’d against Lat/Long coordinates and there are hard ways.>>


What CS are your inputted points referenced against? What coordinate system did you assign to your drawing?

 

Note:

If your points are ref’d against ‘geographic coordinates’ (Lat/Longs) that’s fine. If you assigned Lat/Longs to modelspace then you need to change it to a ‘projected coordinate’ system because if you don’t then the linear distance will be DEGREES instead of FEET.

 

To make the linear distance Feet you can assign the appropriate State Plane and Zone where you can specify units of Feet, this of course, is assuming your site is in the US. (You may need to delete existing points then reinsert your points again after you’ve changed the CS to State Plane.)

Chicagolooper

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Message 3 of 8
rl_jackson
in reply to: brodymedhi

You appear to have your units set to Architectural based on the dimension your showing.

 

At the command line, UNITS = Decimal

 

While your there make sure that INSUNITS= 0

 


Rick Jackson
Survey CAD Technician VI

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Message 4 of 8
brodymedhi
in reply to: ChicagoLooper

So this project is located in Ulysses Kansas, so I chose the NAD83 Kansas State Planes, South Zone, US Foot. Which I believe the survey was also done in. The thing that makes no sense to me is the points are showing up perfectly on the map however my distances are completely wrong. I changed all of my units already and that did not make a difference. I've restarted the program, deleted all the point and reinserted the points multiple times and nothing seems to work. Is there a way that my scale could be off?

Message 5 of 8
brodymedhi
in reply to: rl_jackson

Rick, thanks for your reply however i've already changed all my units already and it hasnt done anything. 

Message 6 of 8
ChrisRS
in reply to: brodymedhi

I do not have a solution.

 

My suggestion would be to post your drawing and point file. Post the aerial photo if not too large. 

Christopher Stevens
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Message 7 of 8
ChicagoLooper
in reply to: brodymedhi

Hi @brodymedhi 

<<...I chose the NAD83 Kansas State Planes, South Zone, US Foot. Which I believe the survey was also done in...>>

 

Would it be possible to upload a sample of your Surveyed points? Eight to ten points with their corresponding x, y, and z values will be good. The points are needed to verify the point locations. Once the point locations are verified in Civil, you can measure distances in google Earth Pro.

 

BTW, the DISTANCE in GE Pro should be measured between two push-pins inserted by  entering their Lat/Longs and those lat/longs can be determined from C3D's modelspace. A line drawn in GW Pro using 'visual cues' such as utility poles is not accurate when compared to a measurement between two Lat/Long push-pins.   

Chicagolooper

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Message 8 of 8

I thick you need to look at the annotation scale on your dimension.

 

Based on what you show in the properties palette, the dimension showing is scaled to the 3/4" = 1' scale.

3'11" = 3.917'

 

3.917' * 12 / (3/4) = 62.672'

 

 

 



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Andrew Puller
Maitland, NSW, Australia
Windows 11
Intel core i7 11800 @ 2.30 GHz with 32GB Ram
Civil 3d 2023

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