Big point clouds are here to stay in the Civil world. I feel like Autodesk hasn’t really given us all the tools we need to get the job done. So I want to introduce a great open source program Cloud Compare (download link). Please donate if you start using it heavily.

Cloud compare will really help with the heavy lifting and pre processing of point data before going into the Recap/Civil 3D cycle.

If your feeling lazy watch the video here.

Alternatively read on

Cloud Compare

1. Drag drop your point data LAS/LAZ/XYZ/CSV straight into cloud compare
2. Tick off all the things you don’t need. I only leave on Classification, Apply to All
   
3. Say Yes to All on the coordinate shift. It will move it back when you export it, so Don’t panic!
   
4. Give it a spin and check out those trees (if you have any)
   
5. Lets get rid of the trees, select the clouds in the DBTREE (use ctrl)
   
6. Go to Edit – > Scalar Field – > Filter by value. We want to filter the ground points which are class 2 (See Classification here). So the range will be from 2 to 2
   
7. You will now have a point cloud with no trees in your viewer. Next we want to reduce the amount of points, we call this thinning.
8. Firstly check how many points you have in your clouds. You can do this be looking at the properties on the left when selecting the cloud
   
9. Your final result you want is between 1 -2 millions points if your are working with the survey to create corridors and volume surfaces. (if your are using gradings you might want it to be less than 500k but we can do this in Civil 3d later.
10. Edit – Subsample
    
11. The amount you reduce the point spacing to really depends on what your smallest ground feature you need to be able to extract from the point cloud. So if you know you have a drain that is only 500mm wide that you need to be able to see, don’t go bigger than 500mm. It’s a bit of a trial and error thing though, but the generally principle is we don’t need points every 5 cm.
    
12. The last thing you want to do is merge the file together and export
    Edit -> Merge
    
13. File -> Save. Cloud Compare will export what ever you have displayed when you click this. Chose LAS/LAZ and change the extension to LAZ when you save. LAZ is way smaller than LAS. Its also a good idea to note the thinning and class you filtered it to.
    
14. Now its just a matter of creating a Recap Project and drag dropping this LAZ file in there. Once your done hit save and go over to Civil 3D.
    
15. You can read in a RCP file from the Insert Ribbon – > Attach Recap Point Cloud or Type POINTCLOUDATTACH
    
16. After you attach, one of the first things you want to do is change your viewframe back to 2D wireframe. It will make the point cloud disappear and replace it with text but you can still use it and you wont get the performance lag you get in 3d wireframe
    
17. Now we can select the point cloud and chose “Create Surface from Point Cloud” from the ribbon
    
18. Give it a good name and include the capture date of the survey EG-SURVEY_YYYY-MM-DD
19. Do your self a favour and put a link in the description the the source files you used to create the surface as well.
20. Don’t click create surface yet. You can now filter the points down more or clip to box only first. But we have already filtered it down pretty good in CC. As mentioned before make sure you are less than 2M
    
21. Lastly Make sure you change the filtering to “No filter”. The filter is only used for Unclassified point clouds or photogrammetry points that have trees/buildings and cars in them.
    
22. You should now have a surface in Civil 3D that is performance friendly
    
23. Do yourself a favour and data shortcut it out. Then data shortcut it in to a separate design file before working.