Creating Surface from Point Cloud Error

[Anonymous]

I am trying to create a surface from a point cloud. I have done this a hundred times in Civil 3d 2018 and never had a problem. Now, in civil 3d 2020, I create the surface and it comes out a jumbled mess. There are many points missing and shear walls somehow appear. I've tried everything I can think of, but the only thing that has changed is that I switched from 2018 to 2020. Is this some sort of bug? Am I doing something wrong? Please help.

Thanks

[tcorey]

Take a look at your surface statistics and check the lowest elevation. (Surface Properties, Statistics tab)

Is that low elevation 0.00? If so, go to the Definition tab, in the upper box, under Build, set Exclude elevations less than to Yes. Set Elevation < to a number above 0, something closer to your actual elevations.

[Grover_Puma]

perhaps it is a command that activates and deactivates the level of detail of contour lines that command is LEVELOFDETAIL to activate and LEVELOFDETAILOFF to turn it off.

[ChicagoLooper]

I agree witj @tcorey , it’s good advice. 

Are you bringing in your points from recap? If you are, then take a moment to review the Imported rcp, don’t be too quick and go straight to creating your surface. Using the View Cube, switch to Front View. Zoom in and you’ll see varying elevations of points. From here you’ll also be able to see if any points are too low or too high. The points are generally bunched up and within a certain ‘elevation range.’ I bet you have a good feel of what that range should be just by looking at the points. 

[Anonymous]

My minimum elevation is 727' which seems right. My process includes taking a LAS file and weeding down the points in Cloud Compare (open source software) and then converting it to an RCP in ReCap. Every time I convert this point cloud to a surface it seems to remove way more points than intended, plus the surface never looks the same each time I create a surface from the same point cloud.

Again, I never had this problem until I switched from 2018 to 2020 version.

[TerryDotson]

Try going straight from your weeded LAS file to a Civil3D TinSurface using this freeware from the Autodesk AppStore ?

[Anonymous]

I downloaded the add-on and tried to get my weeded LAS file to import and got this error

[TerryDotson]

(Revised) I just checked and it determines the size based on the LAS file bounds.  Any possibility of posting the LAS file (ZIP it first)?  You can go straight to the Create Surface tool, then zoom extents.  Feel free to email dotson (at) dotsoft (dot) com.

[Anonymous]

I tried to email you but it wouldn't send. Here is a link to the LAS file: https://barkerlemar1-my.sharepoint.com/:f:/g/personal/agehrts_barkerlemar_com/EpStJZpJ6_xBrOFIvbpDk5...

[TerryDotson]

Thanks for sharing the download (our email limit is 20mb). This will allow everyone trying to help (each in different ways) to be able to provide much more intelligent answers ! 

One important point, looks like CloudCompare created a LAS file with an invalid bounding box in the header!  That's what caused the error in our freeware and I verified it with LASINFO (see attached).

I'll be back in touch in about 12 hours (it's 7pm here).

[Pointdump]

Adam,
Thanks for posting your data.
A couple of observations. Your "V2" LAS has no projection information and contains more than just Ground (2) Points. I would use >>>LAStools<<< to keep just the Ground Points, and then in ReCap decimate some points. Using all points makes such a heavy surface that Civil 3D slows to a crawl.

Dave

[ChicagoLooper]

I agree with @Pointdump your point cloud doesn't have a projection. It could be anywhere, Florida, Iowa, Ecuador, Australia, Antarctica, well maybe not Antarctica, but who knows?

Here's the rcp in C3D.

I then proceeded to create a surface. Of course, I had to let it run overnight.

[TerryDotson]

So as I mentioned, the LAS file CloudCompare created has a bad header and (like most tools) our freeware depends on a valid header.  Consider contacting them about it.  Try the attached tiny LAZ file which is your weeded LAS file corrected (and compressed).  It took less than one second to create the TinSurface on my 5yr old (but still very capable) machine.

[TerryDotson]

---

@Pointdump wrote:

I would use >>>LAStools<<< to keep just the Ground Points ...

Be aware that LasGround is not part of the freeware and needs to be purchased for commercial use.  Use of the unlicensed version can introduce undesirable results including data loss in the files produced and white noise.  See the 14th paragraph of the read-me file.

http://lastools.org/download/lasground_README.txt

[Pointdump]

Terry,
Thanks for the heads up. To be honest I didn't read that far. Martin is kinda long-winded, and my eyes glaze over after a couple of paragraphs of his ReadMe's.
LASGround seems to group Ground (2) Classification and Last Returns, but all the rest of the points are grouped under "Unclassified". I usually use LAS2LAS to "keep" only those Ground Points. Now I'll have to put on a pot of coffee and try to stay awake through that ReadMe.

Dave

[lim.wendy]

I enjoy reading all the workflows in this post, very good tips @Pointdump , @TerryDotson, @ChicagoLooper!

@Anonymous, did any of the suggestions help? Let us know 😉