Oakwood Engineering News

26 September

Faro Scene - Placing PointClouds in Real World Coordinates: a tutorial for beginners

Creating amazingly accurate pointclouds from 3d laser scanned information is one thing, but how useful is the pointcloud information if it's floating miles away from the project base point and can't be related to any CAD drawings or Revit Models. The trick is to get target coordinates shot on site using a Total Station traversed from the real-world project base point. The centre crosshair of some checkerboard targets should be shot using the TTS (Top Tip: try to find targets that you know will have been quite close to the scanner, so you can definitely make out the ID Number or Name). 3 targets would in theory be enough to place Pointcloud accurately, I personally like to get as many as possible and use the best ones at registration stage. This is because occassionally with paper targets the light can reflect and you can't read the name/number.

When you have registered all the scans together and you are happy with the pointcloud create a new parent cluster (Faro Scene is the software we use). Make sure all sub-clusters are locked and lock the parent cluster as well. Then I make yet another parent cluster and leave this one unlocked. Add all target coordinates into an excel file with 4 columns only - name of target; x coordinate; y coordinate; z coordinate. They must be in that order. Save as a .csv file

Go through the scans in planar view and name each target (if you've not already done that) to be the same as the name/number you used in the excel file (exactly the same). Go to file>upload, click the drop down menu and select surveyed points and then navigate to your saved .csv file. import to workspace. A new file will be created called references with all the target coordinates listed. Right click your parent cluster (the very top one) and place scans using targets.

There is a great tutorial video available on Youtube here https://youtu.be/PM7GeRGsXyM