Using a point cloud (snaps)

[darrenpedder]

Hi all,

Hoping you can help me with using a point cloud.

I have been sent a point cloud survey (LAS file). I have taken this and opened it in Recap Pro and saved it as an RCP file. Then I have linked the point cloud RCP into Revit. I get the warning about larger than 30000 when linking (using shared coordinated), but it seems to link in to the location correctly.

So, essentially it looks right, but I cannot snap to any point on the PC. I want to query levels on some points. This is my main query.

I also have tried to output a mesh of the point cloud from Recap, which gives me an RCM file. Again, this looks okay. But from my searching it looks like this is really difficult to have it as an underlay to the point cloud. I tried to open the RCM in Cloud Compare, and this lets me query levels, but this does not appeat to be correct - circa 10m out.

Hoping you can give me some pointers please. Thanks.

[barthbradley]

You need to move the PC closer to the Internal Origin.  

https://knowledge.autodesk.com/support/revit/troubleshooting/caas/CloudHelp/cloudhelp/2019/ENU/Revit....

Are you using the PC to model the Building? I would suggest Linking the Building Model into a Site Project to coordinate it with its physical location in the real world. 

[darrenpedder]

Not quite. The point cloud is a survey of a bridge structure at the corner of the site. The model has been setup with coords like this:

1) Topo survey (DWG) linked in center to center

2) Coords acquired from DWG

3) Project base point moved to a survey point

Is there any way to do this without upsetting the current coordinate system ?

[barthbradley]

So you are Acquiring Coordinates from the DWG?  Are we talking GIS Coordinates?  

Specify Coordinates Before Linking Site Data | Revit 2019 | Autodesk Knowledge Network

Linking DWG Files with Grid Coordinates | Revit 2021 | Autodesk Knowledge Network

[darrenpedder]

Yes. The point cloud is from the same people that provided us with the topo survey, set to ordnance survey coords.

[darrenpedder]

Assume nothing wrong with this approach ? Done a few projects this way and shared coords work well so far

[barthbradley]

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@darrenpedder wrote:

Assume nothing wrong with this approach ? Done a few projects this way and shared coords work well so far

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I'm unclear on the Point Cloud's purpose here (or what you did in the past), but if you are Linking the Point Cloud via Shared Coordinates (or Linking anything for that matter) and it is landing in the Project too far away from the Internal Origin (as the error message is indicating), then the relationship between Survey Point Origin (not to be confused with the visible marker) and the IO, needs to be reduced.   

[darrenpedder]

You can see on the attached the point cloud loaded in. We are building low rise housing near a bridge, where we need to provide a new stair and ramp access up to a higher level. You can see the ramp design on the 3rd image.

The existing bridge has buttresses that we need to build over, so I need to be able to query the point cloud for levels to check coordination.

The 2nd image shows the full site with the PBP, SBP and IO shown. The coords on the SBP are to ordnance survey.

[darrenpedder]

Anyone else have an idea ?