Point Cloud Alignment

[dbanyard]

We need tools that help align point clouds to data in autocad, revit, etc.. Finding wall surfaces for alignment, or using multiple points for rotation and alignment would help in making the point cloud data more consistent in placement. Interior scans are much more difficult to locate especially when you cannot have survey control. When scanning in very enclosed locations, alignment becomes paramount to dealing with adjacency and coordination.

[mbruce71423]

I agree.  Right now I have to find what I think are work planes that will translate to the xyz planes in my Inventor models that I am overlaying with the scan. But the accuracy, and more importantly, the time it takes to align them is very clunky, if that is a word?

[mlabell]

Coordinates are the most paramount step in making sure that everything is located correctly throughout a project.  From experience you need to give a coordinate to your scanning provider that is in your design application.  Never rely on workplances and picking on a pixel to utilize an alignment method.  Those are considered best guesses and can create major error or tolerance stack up throughout a project.  Basic steps of simplified scanning process.

1. Give point to scanning vendor of a column/location on a wall.
2. Have them measure an alignment (row of columns or wall) to rotate building north.
3. Scan and register based on steps 1-2.
4. Import point cloud into modeling environment which will fall directly on top of modeled environment.
5. This method does not require survey coordinates, but does require that the vendor understands slightly more advanced measurement techniques in the field, meaning they just cant turn on the scanner and let the registration software figure things out.

[dbanyard]

We are not using a scanning vendor.. we scan ourselves. Other software like Scene allow for alignments that can use planes and other markings that we may have in the environments. Your alignment is only as good as the environment and markings you have, but at this point recap is limited only to origin movement.

[foh1958]

I have a point cloud that is not set to a coordinate system and appears not to be level.

Can I reset cloud to my system or does the project have to be rescanned.

[mbruce71423]

Yes you can but it depends on what software you are using. If it is Inventor, you can edit the alignment in the drop down menu in the browser which I am familiar with in detail. If it is in Recap I know you can realign the cloud as well but have not done it there because I make the alignment adjustment in the Inventor program. I know you can also import the cloud into Navisworks and align it there as well. Let me know what program you are in and I will try to give you more detailed advice. Maybe a GoToMeeting if possible.

[tim.vetter]

I would LOVE to align my cloud project to bottom of our factory crane beams.  I posted a similar idea a while back.  Create-survey-points-with-1-2-or-all-3-axis-values

[BrianMcKinley]

Such tools could be very handy. Currently, I spend a significant amount of effort forcing the point cloud to a coordinate system. 

I understand that survey points provide accuracy but that just isn't practical, or cost effective, in many cases. 

[tim.vetter]

My workflow for aligning ReCap point cloud projects requires me to reference my un-aligned data in AutoCAD, rotate and move this data, then transfer the resulting aligned coordinate locations back into ReCap.  ReCap now allows adding a NWD CAD file to a ReCap project.  It would be very nice if ReCap would provide alignment tools so I can align to this CAD data, with matching surfaces or "virtual surveyed" monuments, within ReCap.

For example:  I would really like an interface in ReCap like how we currently combine scan groups.  Scan group on the left and CAD data on the right side of the screen.  I can then easily match up common surfaces or virtual targets to easily align my point cloud data to the CAD data.

FYI-I keep an AutoCAD monuments file with virtual white sphere target locations that have been precisely located in the past.  I use these virtual monuments to locate new scan data relative to the old scan data.