Topic: Limits using Lidar data with Civil 3d version? Could use some advice

[sourdough]

Hi all,
We are getting a chance to use a mobile Trimble Lidar unit (not cheap), and would like to hear from anyone that has used really large and accurate collected Lidar data. What have any of you (being the best of the best), used when dealing with miles worth of work, in 2000' wide swath's of Lidar data. We have been told to  look at Revit, Microstation, Encap or Civil 3d 2014 as software solutions. I have worked with 2011 Civil 3D, and found about a million cloud points to be the limit, and don't know what the latest version can do, and if it has a limit. We are also making 3d models of this data. Anybody with any suggestions would be appreciated.

Respectfully
MJP

[Jeff_M]

Mike,
I don't use this type of data, but here is a quote from a response to a similar question on the Autodesk forum. It is from Matt Kolberg who is quite knowledgeable in this data format.

A surface from a point cloud uses a maximum of 1.5M points; this is just life as a point cloud. . There is absolutely no advantage to use a point cloud for surfaces. Sure it performs better when it brings in 10M points, but if not all are used, who cares?

Also with the cloud you need to wait for the software to index the file. It's just an extra step in a fruitless workflow.

Make a surface
Create a data clip
Add point file (never import those points and use a point group)
That is the best way to make a surface from a lot of points.

One more thing about LiDAR that people often overlook is weeding. 2 things MUST happen if they haven't already.
1. Filter the points for ground points only. No trees, wires, buildings etc.
2. Decimate the data. You don't need points every 2cm. Decide on a reasonable resolution and ask your LiDAR provider to give that to you. But not just a simple resolution change' they need to be intelligently weeded. More points near surface breaks and less in uniform areas. Often 10M points can be decimated to under 1M without a noticeable change in your surface.
Matt Kolberg
Cansel - Autodesk Division
http://www.cansel.ca/

[sourdough]

Thanks Jeff. As I learn more about this new system from Trimble I'll share when possible.

Mike

[dgorsman]

We use it more for "vertical" 3D work (plant sites), but we were also using it in 32-bit AutoCAD 2008 so we understand some of the economy involved with large point sets.  We get our scans parceled out into reasonably sized working areas, so we don't have to bring in the entire data set.  We don't have the option of getting our data filtered/decimated as we would likely lose important areas.  What really helps is pointing out to the people doing the scanning where the important bits are, so they can cover it from multipe directions and/or appropriate resolutions.

Make sure you check out the ReCap tools if you have the 2014 releases *AFTER* you check your video card.  Its requirements a little more strict than the other applications.