Help Adding Surveyed Ditches to Lidar Contoured Surface

[bryancollins3174]

Here is my situation.  I've been given Lidar contours ( as horrible as they are) for my project area.  I've also been given surveyed ditches.  I am being asked to override the Lidar data with the surveyed ditch data.

So far this is what I've been doing and it has been taking forever and I'm wondering if there is a better way.

1- Built surface EG by adding Lidar contour data to Surfaces-Definitions-Contours

2- Connected the ditch points with Feature lines.  Offset the Top of Ditch feature line 3 to 5 feet.  Exploded, Flattened, and then created new feature lines. Told it to pull elevations from EG. Added additional vertices.

3- Deleted Lidar contours data from Surfaces-Definitions-Contours

4- Went around trimming out original Lidar contours inside of the new 3 - 5 offset feature lines

5- Added the newly trimmed Lidar contours back to Surfaces-Defintiions-Contours

6- Added all feature lines to EG surface

7- ReBuilt EG Surface.

8- Get ton of errors so I have 100 or more bit-by-bit overlaps that I have to trim out due to adding all the additional vertices I guess.

9- ReBuilt EG Surface and now good to go.

So far I've used that procedure on 4 areas and it has taken about 2 days or more for each area just to get a decent combined surface.  Each of these surfaces are being placed in their own drawing because Civil 3D 2010 can't seem to handle them all in one drawing.  I still have 4 or more areas to go.  Really not sure how I'm going to handle 2 surfaces for the areas in which Force Main will be layed out between the overlapping surfaces.

Is there a better, simpler, easier, faster way to accomplish the same task?

Thanks for your time and efforts.

Bryan Collins

Cadd Technician

Windows XP Pro w/ SP3, 3 GB switch

Civil 3D 2010 (32bit) w/ SP1, SP2, SAP, & SP3

[Matt.Anderson]

Bryan -

I would keep it simple.

Build your surface from LIDAR.  Save the drawing and create the data shortcut.

Build your Ditch surface in different drawing.  Bring in LIDAR surface from the shortcut.

Create a new surface for EG, paste LIDAR, then paste Ditch.

[bryancollins3174]

Matt,

How can I build a surface with just ditches?  Each area has anywhere between 30 to 60 or more individual ditches.  Confused.

[Matt.Anderson]

What did the surveyor provide you?  Is it just crossing data or full topo of the ditches...

[bryancollins3174]

The surveyor gave us top and bottom of ditches around rcp's, drives, and in 50' intervals along road.  They shot other stuff, but we are using those shots for location only. 

Lidar is to be mainly used for elevation with ditch shots added.  Due to the time of year Lidar was shot majority of the ditches were filled with water.  Otherwise the Lidar is less than a ft off from ground shots elsewhere in the project and that is good enough for the client.  We need the ditches to show accurately to show the correct cover over the Force Main and Gravity Sewer lines when crossing said ditches.

[Matt.Anderson · Accepted solution]

Ok.  This would be like any other survey.  Deal with the surveyed data in a different surface than the data provided by others.

Draw your tops and bottoms and make that Surveyed Surface good.  Make it one continuous surface - linear with what ever fingers the surveyor provided.

Your final surface will include the LIDAR contours with the Surveyed Surface pasted ontop.

[jmayo-EE]

Like Matt, I would also keep the ditches separate & paste the surfaces. If things don't look good where the two surfaces meet, this may save you some time.

http://www.civil3d.com/2010/04/blending-surfaces/

[bryancollins3174]

Matt,

I tried what everyone suggested, but I got an error message saying my Lidar surface was corrupt.  I don't understand how it can be corrupt when it is perfectly fine in the Lidar drawing, but when I dRef it into my EG drawing it seems okay with no symbols showing errors.  Then I go to paste it into surface EG it states that the Lidar surface is corrupt.

EG drawing setup:

EG_Ditches (Surface made up of only the ditches)

EG_Lidar (Surface created from lidar contours drawing created in ArcGIS and saved as dwg)

What I did:

I created an EG surface

Pasted in EG_Lidar (error message EG_Lidar surface is corrupt)

Any suggestions why this might be occuring.

[bryancollins3174]

Well I opened the EG_Lidar drawing and ran an audit on it and the audit reported back that the Tin Surface EG_Lidar has become corrupted.  So don't see how that could happen.  All I did was select all the contours and created a surface and that caused the surface to be corrupted?  Any idea why this might be happening?  I keep wondering if it has anything to do with the lidar drawing originally being created in ArcGIS and it holding all the elevation data because every now and then I get query errors, but there is no querying going on within the drawing...at least nothing has been setup for that.

[Anonymous]

Stupid question time, since I don't use ArcGIS - Are the countours shapes or are they 2d polylines?  Is it possible to get the contours into a acad dwg as 2d polys (at elevations) before you create the surface?

Or, can you get a tin surface from arcGIS, and create your surface from that?

Reid

[bryancollins3174]

Reid,

When I got the lidar contours drawing from ArcGIS the contours were polylines with elevation values.

Once I got past the corrupted surface I was able to paste it and the ditch surface into the new EG surface.  Everything seems fine for now but let's see if it stays that way or not.

Another question though...how can I force contours to not touch, intersect, or cross other contours?  I have Contour Smoothing turned off, but the surface built from the lidar is horrible with crossing and intersecting contours. Screencap attached.  Any suggestions on combatting this one?

[Matt.Anderson]

How did you create the LIDAR surface?  Did you use the GIS wizard to create the C3d surface from the GIS contours? or are you using a true LIDAR point set to create the surface? 

Did you apply any boundaries? move? translate during the paste?

[bryancollins3174]

We started out with a true Lidar point set for an entire county.  Minimized it to the 30 miles or so that we needed for this particular project.  Tried importing and creating surface, but Civil 3D couldn't handle it as we were previously informed that it could.  Had our GIS specialist import it into ArcGIS 9.3 so he could create contours.  He saved it out of ArcGIS as a .dwg file.  I wblocked out the contours to get rid of the extras and started a new drawing.  Created EG_Lidar surface by going to Surfaces-Definitions-Contours and selected all the contours (all boxes were checked when asked how to create surface).  I then created a boundary and rebuilt the surface.  The surface for the most part is just like the original polyline lidar contours where they cross and intersect each other causing errors to be displayed due to crossing breaklines.

But that is how I created my Lidar surface.

[Anonymous]

So, the contours that you got from the gis export were touching or crossing?  If that was the case, you'd get the same result in C3d.  It sounds to me like you'd need to edit the gis created drawing 1st.

In creating the C3d surface, have you tried weeding the contours?

Reid