AutoCAD Civil 3D General Discussion

AutoCAD Civil 3D General Discussion

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robert.thomson
Posts: 19
Registered: ‎07-06-2007
Message 1 of 7 (1,117 Views)
Accepted Solution

Smooth Road Profiles created from Lidar

1117 Views, 6 Replies
08-14-2012 12:02 PM

We have lucky enough to obtain LIDAR for most of our small City as well as ground only points.  My problem is that profiles produced using it are rough and jagged (see attached).  I've tried contour smoothing to no avail as well as point removal.  Perhaps I haven't just tried enough options.

 

Should mention also I have breaklines along the CL alignment as well as Edge of Pavement.

 

Any ideas?

What would a normal preliminary survey be in your area? We usually see surveys with a cross section every 25m and for each feature of the road. At the most this is what I'd have to define my EG in this instance. Clearly the LIDAR data is overkill for road design. 

 

Maybe you could try to insert a point along each of the breaklines at common interval and redefine your EG surface to be something like EG_reduced. Good Luck.

*Expert Elite*
sboon
Posts: 2,226
Registered: ‎11-08-2005
Message 2 of 7 (1,103 Views)

Re: Smooth Road Profiles created from Lidar

08-14-2012 12:52 PM in reply to: robert.thomson

With Lidar you're pretty much stuck.  There's really too much data and without proper breaklines it doesn't triangulate along the road crown as it should.  We have had some success at creating a "fake" ground profile by drawing a featureline to trace the centerline where it's visible in the photo.  You can either snap the featureline points to the Lidar nodes or use the Elevations from Surface command, then project the featureline onto your profile view.

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Neilw
Posts: 2,341
Registered: ‎09-04-2006
Message 3 of 7 (1,102 Views)

Re: Smooth Road Profiles created from Lidar

08-14-2012 12:54 PM in reply to: robert.thomson

Judging the contours in the plan view it appears the LIDAR surface has issues. The contours in the paved areas should not be meandering like that. I'd run some checks on the surface and source data.

 

Do you receive breakline data with the LIDAR dataset?

Neil Wilson (a.k.a. neilw)
Infrastructure Suite/C3D 2013, LDT 2004, Power Civil v8i SS1
WIN 7 64 PRO
HP Pavillion h8xt, i7 2600, 12 GB
RADEON 6450, 1 GB
http://www.sec-landmgt.com
Contributor
robert.thomson
Posts: 19
Registered: ‎07-06-2007
Message 4 of 7 (1,059 Views)

Re: Smooth Road Profiles created from Lidar

08-15-2012 05:02 AM in reply to: Neilw

No we didn't but I have 2d polylines as breaklines in the drawing at the edge of pavement and the centerline.

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jmayo
Posts: 3,030
Registered: ‎11-13-2006
Message 5 of 7 (1,051 Views)

Re: Smooth Road Profiles created from Lidar

08-15-2012 06:05 AM in reply to: robert.thomson

Like Steve, I would look at using the lidar data to recreate the Roadway. Either with FL's or a layout profile and simple corridor to extract the FL's for CL and EOP.

John Mayo, PE
IDSP 2014
Win 7 64, Xeon ES165@3.2Ghz,
64 GB RAM, Quadro K4000 (x2)
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LeafRiders
Posts: 349
Registered: ‎09-28-2010
Message 6 of 7 (1,026 Views)

Re: Smooth Road Profiles created from Lidar

08-15-2012 01:00 PM in reply to: jmayo

What would a normal preliminary survey be in your area? We usually see surveys with a cross section every 25m and for each feature of the road. At the most this is what I'd have to define my EG in this instance. Clearly the LIDAR data is overkill for road design. 

 

Maybe you could try to insert a point along each of the breaklines at common interval and redefine your EG surface to be something like EG_reduced. Good Luck.

Contributor
robert.thomson
Posts: 19
Registered: ‎07-06-2007
Message 7 of 7 (995 Views)

Re: Smooth Road Profiles created from Lidar

08-17-2012 04:20 AM in reply to: LeafRiders

Thanks to all that replied, for now I think the idea of placing a point on the Lidar Surface every 25m would be a great idea combined with a 3D poly breakline.

 

I have always had problems with jagged profiles and a 3D poly breakline has always solved them.

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