Newbie needs help, from point cloud to finished 3d model

You can create a series of section elements and create a surface form sections using more than two sections.

The direction of the elements must match - left to right or right to left, clockwise or counter-clockwise. If they close, the start points should also align.

I used display depths and rotated views - some via key-ins, some graphically. There is also a delta display depth key-in so you can easily move forward and backward in your slice. For example, if your view is aligned so the view Z runs from the front to the rear of the tank and you are looking at a specific depth slice, like 1' or 0.5 Meters, to "step forward or back 5 units at a time, the key-in DD=5,5 or DD=-5,-5, followed by a data point in the view, will move you forward and backward 5 units. It basically is moving both the front and rear clipping planes for you in unison.

Then, at each slice, you trace an outline. In a few minutes, you have a multitude of sections to make a surface from.

Other useful key-ins:

RV=90,0,0

RV=0,90,0

RV=0,0,90

Copy View

Rotate View Points

The 3 point view rotation must be done with with the Z axis locked so that the rotation is only around a single axis.

This is useful to align the view and model so that the 90 degree rotations above will allow you to quickly make a top, front and side view of a scanned area when the scan axis is not aligned with the target object.

Some of these can be used with Auxiliary coordinates, but the truth is, I have done many a model without using a single auxiliary coordinate system.

Heya,

Thanks for the replies. I've taken some screenshots and asked about what exactly I need to model. The first image is the wireframe. I made that from just the end planes. I made a patch using CloudWorx and turned that patch into a mesh. I did that for both ends. Then I tied them together using the "Mesh from Two Curves" function. Which gave me the entire wireframe. But then the whole middle part of the point cloud isn't used in the modelling. That bothers me.

Here is the wireframe and pointcloud:

There are a few holes in it. Some are supposed to be there, door as and such others are just errors from the photogrammetric procedures. The las image shows the problem with the method that I've used:

I used Cloud Compare, to check the deviations between my 3d model and the point cloud. It looks ok in the end, but the middle is sort of 'hanging' since the point cloud wasn't used as control for the model.

I asked what the results needs to be. I need to draw the two ends and a cross-section from the middle of the tank. So that'd be three 2d-drawings, I need to draw the outline of the tank, as seen from the side, with door and trap-door markings. And a top view drawing, with door and trap-door markings of all five of these tanks. Lastly a solid, 3d model with doors cut out. One we can measure in, if we need additional info than what the series of 2d drawings can provide. I suppose I can use the 'Region grow -> patch' from Leica CloudWorx for the end sections, but I'm unsure how to do the rest of it...

I hope this long post didn't knock the air out of you guys! 

Best regards,

Jacob Collstrup

Hi Tom/Hi Jacob,

Just to let you know that in Bentley Descartes SELECTSeries 4 the fit cylinder command has been improved so that you don't have to exactly match the cylinder to fit.

Also there is a new functionality in Bentley Descartes SELECTSeries 4 called Model By Section which I think could be quite handy to model the water tank.

As Benoit said a BETA version of Bentley Descartes SELECTSeries 4 is already available and there is also a Descartes SELECTSeries 4 BETA community which can be access here : communities.bentley.com/.../default.

HTH,

Mathieu

My best suggestion is to crop sections of the tank and use the fit plane or fit cylinder command. It is relatively easy to use. However it can sometimes be overwhelming if you cannot get it to match correctly. I dont have it up in front of me, but I have used it to create tops of buildings and stuff like that. I know that you are able to drape a raster image over the cloud and I wish that it could also work in a similar function for a filled block or cylinder but it doesn't.

Also, when cropping a pod, you can export the cropped section so it might be a good idea to look at the entire tank and determine the best way to crop it. that way you can have each cropped section as a separate pod file and be able to turn parts on and off so your action snaps dont select a wrong point.  

I will keep it on my mind and if any thing else pops up I will let you know.

I also may have something laying around that describes smart snap and visual explorer. I will keep you posted.

-Tom

I have a .las point cloud which also exists as .pod now. The point cloud is derived by photomodeler scanner, and so is based on images, so there is no intensity information. Just X,Y,Z and R,G,B.

It's the interior of a of a concrete overflow water tank. In cross section it sort of resembles a loaf of bread. Not entirely cylindrical. I'd like to make a solid 3d model from it. I don't know if the point cloud is filtered, but lets assume it isn't. I can take some screen shots of the project tomorrow when I'm back at the office.

-Jacob Collstrup