State Plane Coord Point Clouds

[GPRS-DTimmons]

Good Evening,

We use laser scanning and insert Recap projects (RCPs) or individual point clouds (RCS) that are on land survey control. These coordinates are large.  I see the following problems with Revit when inserting onto a Shared Coordinate System:

1. When inserting a point cloud, Revit uses a scale factor, corresponding to International Feet, of 3.280840. The scale factor is truncated to 6 decimal places.
2. Changing the scale factor to 3.280833 (corresponding to US Survey Feet), the point cloud coordinates are short because the decimal places are truncated to 6 decimals. This means a survey coordinate of 1,700,000 feet now appears 2 inches smaller inside Revit.
3. In Revit 2015, the point cloud is not allowing us to snap to the point cloud if the coordinates are large. The same clouds with smaller coordinates will allow snapping to the cloud. This was not an issue with Revit 2014.
4. One can insert one large point cloud into Revit 2015 on Shared Coordinates. If you export out parts of that same point cloud from Recap, and reference those parts into Revit, they link into Revit 2015 at slightly different locations.
5. Problems with large coordinates handling Point Clouds do not appear to be problems when linking in large coordinate AutoCAD/Civil 3D files. There seems to be a problem with the interaction with Recap.

We see hundreds of scan jobs a year. The interaction between Navisworks, Revit, and AutoCAD are very important with regards to point clouds.  Of the products, Revit is having the most trouble.  These items need to be ironed out to make the products more intuitive to the end users.  A great alternative is if Autodesk makes it official that point clouds over a certain coordinate value should not be used.  Maybe that’s the 20 mile warning?  Right now, I don’t believe that is clear. 

[Lance.Coffey]

Are you seeing the 20 Mile warning (like the one below) when linking the large point clouds?

Or is the geometry of the large point clouds larger than 20 miles (e.g. you couldn't fit all of the elements within the Revit model into a box 20 miles on a side)?

[GPRS-DTimmons]

Thanks for the reply.  No I do not receive that 20 mi warning when inserting a point cloud file (or Recap project file).  You could fit the points of the cloud(s) in a box 400 ft by 800 ft.

I guess we'll just start avoiding state plane clouds in Revit.  Its a magnificent piece of software, we're just trying to nail down limitations.

[Lance.Coffey · Accepted solution]

I found a similar thread on this topic: Scale of Point Cloud on Survey Control

As Alaaeldin mentioned the issue with the scale precision has been logged with our developers (as a wishlist item).

It doesn’t look like US Survey Feet are currently supported (as a unit) within Revit: Support for US Survey feet

And while the difference between International Feet and US Survey Feet would only be 20mms (within the 20 mile limit of Revit model geometry), when you add Survey Points that are millions of feet away from the geometry and a 6 digit limitation on the scale factor, then you can readily see greater variations in position.

[Anonymous]

Give Autodesk Dynamo a try. I'm able to force the scale from 3.280833 to 3.28083333333333 but I still end up a little short. The good thing is, it's less than before. The point cloud will still not hit my control gridlines

[eco.arjay]

I got the same warning as this. can you please enlighten me about this problem and how to correct this kind of problem. by the way I'm using Revit 2017.

[Lance.Coffey]

The following Revit Clinic post has information on this warning:

Revit 2011 2 Mile Limit Now 20 Mile Limit

If the point cloud has extents greater than 20 miles, you would need to adjust this (possibly in Recap) to prevent the warning, and the associated issues of resulting large coordinates within the Revit model.

[snaidu]

Point cloud data has already set real coordinate , we dont want to change in recap too, then what is the solution in revit.