- Harold Rempel at URS Corp. did agree with me that contours and LiDAR data just don’t mix.
- The question was raised on how best to check a derived 3D CAD model against the source point cloud.
- It seems to me that if this is still not a standard procedure then we have a lot of best practice work to do.
I came across a revealing set of comments on the topic of quality control/checking procedures, but before that I wanted to be sure that readers saw the recent comment from Harold Rempel at URS Corp. If you have not had a chance it is worth a couple of minutes. Bottom line – contours and LiDAR make strange bedfellows, as they say. It’s the clash of 2 different technology eras and workflows. Change is overdue, and we all need to make it happen.
On a similar note, the issue was raised on one of the forums about how to check the final derived CAD model against the source point cloud to determine if their were any mistakes in the processing. The person noted that the standard operating procedure for traditional survey work was for a “checker” to identify problem areas with a red marker on a printed check copy. In many offices, standard procedure is for someone new to the project to perform an independent check of the drawings.
As we know it’s not that simple when it comes to 3D, especially when trying to compare point clouds to derived CAD models. One person noted that they took 1 m thick “slices” through the model in each direction to look for mistakes. Someone else noted that there was software available that would automatically perform the check.This would seem like the right direction.
The key takeaway for me from this discussion is how far we have to go in terms of establishing best practices for working with point cloud data. Without standard quality control procedures that the suppliers and the clients can trust we are going to be reinventing the wheel. Combine that with outdated requirements and procedures, such as plotting contours and you can see that as an industry there is a lot of education that needs to take place.
One of the ASTM E57 subcommittees is charged with developing best practices. If you have an interest please become a member. And if you have any thoughts on how to efficiently check a derived CAD model, please share them.