Topic: 3D scans & Revit and/or AutoCAD

[Matt__W]

Does anyone have any experience with 3D scans and bringing that data in Revit and/or AutoCAD?  Let's say you scan a mechanical room.  Does the scanned data somehow translate to individual 3D elements or is it one giant blob of..... stuff?

[dgorsman]

Lasergrammetry returns a set of points, typically *very* high density, more of the "blob" than elements.  There are utilities that can skin those points into surface models.  There are so many points that tools are needed, like CloudWorx or the Faro engine in newer AutoDesk products, to manage them.  I've seen a few users try their hand at brute-forcing node objects into AutoCAD, complaining that performance is "off" at ~ 50k points.   :whistle:

We have been using the point cloud two ways.  The first is a "go-by" to create models where none exist, loading the cloud into a drawing and using piping design tools to run pipe, valves, and fittings that closely match the cloud using some RMS tools to approiximate centerline of pipe.  The second way is an "as-build check", where the point cloud is overlaid onto an existing model to confirm whats in the model is the same as whats in the field.  In both cases we also publish the point cloud to Navisworks NWD which makes viewing model/point cloud combinations faster.

[mjfarrell]

I've had some exposure to Leica Cyclone it's a very interesting approach.

[jonesy]

Does anyone have any experience with 3D scans and bringing that data in Revit and/or AutoCAD?  Let's say you scan a mechanical room.  Does the scanned data somehow translate to individual 3D elements or is it one giant blob of..... stuff?

This is something we are currently looking into too, so I will be watching this thread with interest

[dgorsman]

There's a couple of interesting AutoDesk developments in this area:

123D Catch (formerly Photofly): http://labs.autodesk.com/technologies/123d/ (more digital photography than point clouds but potentially much cheaper)

Point cloud feature extraction for Civil 3D: http://labs.autodesk.com/utilities/civil3d_pointcloud/

Only downside right now is they are public cloud-based, which takes them off the table for most clients.

[Matt__W]

So basically it's a giant blob of points located somewhere in space that you can use to model the existing conditions.  *sigh*

http://wikihelp.autodesk.com/Revit/enu/2012/Help/Revit_User's_Guide/0066-Start_a_66/0072-Using_In72/0107-Using_Po107

[dgorsman]

Right.  There's a few tools from third-party vendors, and a couple integrated into AutoDesk software, which allow a user to cordon of a sub-set of points and use them to construct a plane, box, or tube/pipe/centerline as a guide.

In most cases you can "grow" the size of each point so they overlap to form a pseudo-image in the program.  If the point cloud includes only intensity data then its greyscale which can provide an excellent perspective for fine details.  If the point cloud includes full color data then its almost like a 3D photo.  The really high-end scanners take digital photos alongside the scan, and uses the scan data to stitch them together similar to Microsoft PhotoSynth or the aforementioned 123D Catch.

Point clouds can be *very* frustrating to build a model from scratch.  For example, we get scans of existing facilities in operating/"hot" condition.  The pipes grow and/or lift-off from the thermal expansion so even if they were built exactly to the drawings they can still be at non-orthogonal directions.  Modeling software assumes that everything is perfect e.g. 90 degree elbow joint is *exactly* 90 degrees.  I imagine buildings would suffer from similar problems from settling, construction adjustments to make things fit "better", etc.  We still haven't found an easy path forward from the actual scanned data to an idealized model; there's a lot of fudging/guesswork involved.