Hi all,
How would one remove all points that are inside certain 3D regions?
Assume I have no knowledge about the available pointcloud tools!
I imagine it is easily done using Pointools and a 3D microStation DGN with solids describing the cut-volume, or something like that, but I need to be sure what the proper solution is before I trouble our IT department. We already have (some older version of) Descartes.
About our (run-of-the-mill, I presume?) scenario:
We have huge and detailed lidar scans from airplane of about 60km of new infrastructure, including urban areas. We want to cut away the points where our new project is going to be so we can clearly see and visualise the new structures together with the pointcloud. There are tunnels, existing bridges and other features like cables that we want to keep. We have the entire project mapped out as solids and so forth (or can do that fairly easy in microStation)
It is absolutely necessary to remove the points from the project area. We cannot use a solution where there is geometry blending together with the existing points.
Thanks,Torben, who is promoting pointclouds all I can around here! :)
Hi Torben,
In plain MicroStation you can use the Clip tool (Point Clouds manager->Edit->Clip) to clip out a 3D region using the Slab area selector and setting the mode to Mask.
With recent version of Bentley Descartes you can also set multiple clips on a single point cloud, which can be handy if the points you want to clip out are present and disjointed regions (i.e. : cannot be done with one single slab).
Thanks,
Mathieu
Hi Mathieu, Would you please clarify how exactly it works in Descartes as I am not sure if you write that we can or cannot use our existing 3d model to trim the pointcloud?
The GoalPlease remember that the goal is to have a simple and fast workflow to trim huge and detailed areas of pointclouds.
More informationIn advance I can say that manually picking single 3D-elements would be a hazzle, and drawing shapes or slabs manually a complete and disastrous turnoff. We can probably export to other formats like OBJ if that makes a difference. All our pointclouds are in microstation native format.
IdeaPerhaps there is a solution involving collision checking and classifying the points inside solids (be that obj or microstation native), and then export the cloud without these points?
Again, I apologize for asking this very simple, and very basic question, but I have zero hours experience with pintcloud tools, and I need to be 100% sure we can do what we need with the proper tool.
System: Win7 64bit 16GB Ram - microStation V8i SS3 08.11.09.578. + PoinTools CONNECT. - Intel i7-4800MQ CPU@2.70GHz, 4 core / 8 Logic proc.
If I understand you well you want to clip out the points where the proposed design is going to be, right?
Is so the clip areas would be all the objects detailing the proposed design.
With Descartes you can have multiple clips applied at the same time. Below is a short video showing how to do that.
Unfortunately it seems that only one clip is assigned the point cloud and you cannot multi-select all the clip not assigned with the point cloud to assign them.
I'll check with Bentley Descartes product managers. That might have a better solution to propose.
Thanks for the help so far Mathieu,
Unknown said:...you want to clip out the points where the proposed design is going to be, right?
Yes, I want to completely erase all those points from our pointclouds
Unknown said:Is so the clip areas would be all the objects detailing the proposed design.
Yes, well, using the projects 2D and 3D boundaries should do it
Unknown said:With Descartes you can have multiple clips applied at the same time. Below is a short video showing how to do that.
Good!
Unknown said:Unfortunately it seems that only one clip is assigned the point cloud and you cannot multi-select all the clip not assigned with the point cloud to assign them.
I am unsure what you mean by this.
Do we need to apply one clip from element at the time? If so, that is doable, but would probably be time consuming.
Are there limitations to the 3D element used for the clip? If no, we can make a single mesh or solid that covers all we need to clip, no problem.
As long as we can export a trimmed pointcloud once all the clips are applied?Since none of you have mentioned pointools, I have ordered a Descartes installation and expect it to arrive within days.
Thanks,Torben
Unknown said: Mathieu St-pierre Unfortunately it seems that only one clip is assigned the point cloud and you cannot multi-select all the clip not assigned with the point cloud to assign them. I am unsure what you mean by this.
Mathieu St-pierre Unfortunately it seems that only one clip is assigned the point cloud and you cannot multi-select all the clip not assigned with the point cloud to assign them.
If you looks at the video at the 37 seconds mark you'll see that the only one clip has been assigned the point cloud, so I needed to assign the point cloud to the other two clips, which is cumbersome if you have many separate clips.
Unknown said: Do we need to apply one clip from element at the time? If so, that is doable, but would probably be time consuming.
As the video shows you can select all the element at once and create clips for each of those elements. The big problem is the assignment to the point cloud as explained above.
Unknown said: Are there limitations to the 3D element used for the clip? If no, we can make a single mesh or solid that covers all we need to clip, no problem.
Not sure about this one, but there are certainly limitation, mesh is probably one since a mesh is not necessarily closed.
Unknown said: As long as we can export a trimmed pointcloud once all the clips are applied?Since none of you have mentioned pointools, I have ordered a Descartes installation and expect it to arrive within days.
Yes it is possible. You just need to re-export the POD and in the Export Point Cloud dialog choose Clip for the Region Filter option.