Point cloud to complex profile or similar

[CarlM]

Hi,

I am working with a point cloud (imported from a .e57-file), which among other things, contains a tunnel.

The tunnel is of varying width and height over the run of its length.

What would be the best practice to make this tunnel into a complex profile, object or similar?

What I would like to do is take section-snapshots every meter or so and then have a surface extrapolated between those sections.

Is there a simple way of achieving this that I am missing?

/thanks

[Laszlo Nagy]

I would probably used Rules Shells for these 1 meter segments because it can model the geometry and its thickness is constant.

A few clips of the Ruled Shell:

https://www.youtube.com/watch?v=R-yIe3cgPys
https://www.youtube.com/watch?v=02ZaWDPSYUg
https://www.youtube.com/watch?v=UcyDHKIWRco
https://www.youtube.com/watch?v=2iSjHhc45cA

You know, I can imagine the Rhino-Grasshopper-ARCHICAD Connection would be ideal to do this. Although I don't know if Rhino support Point Clouds or not. But in Rhino it would be very easy to trace the contour at each 1 meter interval, then generate a NURBS surface based on them, and then use Grasshopper to generate the Ruled Shells in ARCHICAD.
Just a thought, I have not tested it myself.

[CarlM]

Thanks for your reply!

The clips are good, but I realize now that I was a bit short on information in my post, and I hadn't really formulated the problem for myself either.

The tunnel is a few km long so I need to write some kind of macro that will follow a 2D-path (center of tunnel) and then every meter make a section perpendicular to the path in order to get the shapes in the image in the previous post. Once I have those section-shapes perhaps the Shell tool is the right approach.

Is is possible to write such a macro in Archicad? Or am I looking at some external software? I will definetely look into what Rhino is capable of - thanks for the tip!

[Laszlo Nagy]

Wow, several kms long and a section at every meter?
So you would have thousands of sections, each section with dozens of points.
Clearly there needs to be an automated way of doing this.
And you have to extract this data from a Point Cloud?

He is a clip I found in which in Rhino you can convert a Point Cloud into a Mesh. You could do that with your tunnel. Then you would only have to slice that tunnel mesh with planes at 1 meter intervals and you would have the section profiles. I am not sure what stage is the Grasshopper-ARCHICAD connection but from those section profile polygons you then may be able to create the Rules Shells. Or maybe you should create Morphs from them.

https://www.youtube.com/watch?v=Z9Zv0E330eo

If you go down this path I would be very interested to see the result.

[Anonymous]

Maybe it can be done with "Mesh Generator", an object made by Masterscript:

http://www.masterscript.nl/epages/78066077.sf/en_GB/?ObjectPath=/Shops/78066077/Products/37

[Erwin Edel]

I thought the whole point of the point cloud was that you would have this information of as-is / existing available in your documentation. Is there any reason why slicing through the point cloud and presenting that as your documentation is less acceptable to communicate than having to manually draft up the whole thing?

It sort of sounds like using the future technology to translate back to the way it would have had to be done in ye olden days...

[Eduardo Rolon]

The problem is that the "future technology" grabs millions of points and you need to simplify it so that it is usalel. For example the minimum amount of points needed to define a plane are 3 if your scan has 10,000 points for that surface then which 3 are the correct ones? or which ones are the ones we agree with? That means that someone has to "draft" the official As-Built.

[Erwin Edel]

How about taking the pointcloud to other software and saving out high-res images?

I think it is even possible to export your model to a pointcloud viewer, combine both and use that communicate 3d information.

I'm not trying to criticise the workflow, by the way, it just seems like a whole lot of work to get a 3d model of an existing 'crude' tunnel that is unlikely to be changed in a meaningful way by architectural elements coming from ArchiCAD.

I assume there is some collision detection needed and I wonder if drafting it all up, when you have the pointcloud available is the most profitable solution.

[CarlM]

Thank you all for your replies and ideas, and sorry for my late reply.

I've been working with the cloud and come to the conclusion that it is too big to do anything manual. One of the problems with the cloud is that when you take a section through the tunnel you won't get the tunnel shape complete since there are installations (pipes etc) that have been blocking the scanner. I've looked at using Matlab to get a spline to do a best fit of the points in the section and thus getting past the "missing" pieces. It isn't that hard to acheive, however doing an itteration, by following a 2D-path in the center of the tunnel, to have it produce thousands of section-splines is beyond my knowledge.
I have also stumbled across a 3rd-party software called 3DReshaper that - at least according to the specs seems to do what I am after. I have downloaded the trial version, but have yet to test it.

I will post progress.

Once again - thank you for your input and ideas!

[Barry Kelly]

Just over a year ago I used the demo version of this ...

http://pointfuse.com/

to convert a point cloud of a castle into a DXF file.
I brought that into Archicad and converted it to morphs.
I think I saved the DXF as an object first and then converted to a morph - I really can't remember.

There is a way of doing it by IFC files as well although I had no success with that at the time.

There is also this which may be worth looking at ...

http://bimm-gmbh.de/en/portfolio/pointcab4bimm/


Barry.