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Imported USGS SHP File Wrong Units

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Message 1 of 8
williamgstewart3
485 Views, 7 Replies

Imported USGS SHP File Wrong Units

Hi, I've imported a USGS SHP file for a preliminary design in imperial units and I noticed that the unit conversion from meters to feet is backwards. According to the USGS info/metadata for my downloaded file my units should be in feet. "The vector lines have elevation attributes (in feet above mean sea level on NAVD88), but this dataset does not carry line symbols or annotation." When I create a surface from the SHP file my elevations are being scaled up by a factor of 3.28 (the conversion from meters to feet), but the SHP file elevations are already in feet. It appears as if Civil3D thinks the SHP file is in meters and converts the number into feet. When I change my surface units to meters the correct elevation in feet is being displayed in meters. Does anyone know how to turn off this automatic conversion factor or how to scale my contour elevation back down?

Thanks,

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Message 2 of 8

Hi William,
Confirmed, using "Create Surface from GIS Data" I get same as you. I don't know how to fix that. Better results with the Attach/Query/Alter Properties Method.
Dave

 

SurfFromGIS_1.png

 

SurfFromGIS_2.png

 

Dave Stoll
Las Vegas, Nevada

EESignature

64GB DDR4 2400MHz ECC SoDIMM / 1TB SSD
NVIDIA Quadro P5000 16GB
Windows 10 Pro 64 / Civil 3D 2024
Message 3 of 8

William,
And if you really want to have fun, grab some Point Cloud data from the same TNM site. Attached.
Dave

 

SurfFromPtCloud_3.png

 

Dave Stoll
Las Vegas, Nevada

EESignature

64GB DDR4 2400MHz ECC SoDIMM / 1TB SSD
NVIDIA Quadro P5000 16GB
Windows 10 Pro 64 / Civil 3D 2024
Message 4 of 8

Thanks for the help, this is my first time importing surfaces from USGS data. When you download the lidar data, how do you see what the current coordinate system is? I imported the data into recap and then C3D, but my point cloud is in the wrong spot.
Thanks,
Message 5 of 8

William,
Usually coordinate system info is in the header of the LAS/LAZ file. To read the header I use LASInfo in the free >>>LASTools<<<. And ReCap does an admirable job of filtering Ground(2) points.
Dave

Dave Stoll
Las Vegas, Nevada

EESignature

64GB DDR4 2400MHz ECC SoDIMM / 1TB SSD
NVIDIA Quadro P5000 16GB
Windows 10 Pro 64 / Civil 3D 2024
Message 6 of 8

I used the lidar data to make my surface and learned a lot. Thanks for all the help!

Here's a good youtube video for anyone else that wants to learn: https://www.youtube.com/watch?v=DKkwjnTbTDs&t=66s 

 

Message 7 of 8

hi @williamgstewart3 

 

as workaround if your project is in Feet, Please go to ambient settings and change elevation unit to meter.

 

01

snoyolar_ddscad_1-1703718096704.png

02

snoyolar_ddscad_2-1703718171293.png

 

create your surface usin GIS Data

Try this one

Simon Noyola

 

 

Message 8 of 8

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