Forums >> General Discussion >> Revit Project Management >> Point Cloud Density

ant

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Now that Revit 2012 can import point clouds we are keen to make use point clouds for existing buildings.

But a surveyor has asked what density we would like the point cloud to be.

Depending on the equipment used, densities up to 0.25mm seem possible. But surely this would create more points than are useful, and a HUGE file.

Accuracy seems to be around +/-5mm, so why would you require a higher density than that? But maybe a lower density is sufficent. 10mm?

Does anyone have any experience in using point clouds, and in particular what a suitable density might be.

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itsmyalterego

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You can't actually USE the point could to make geometry in revit, it's used as a reference to build atop/within.  So rougher data is probably fine.  If I were you, though, I'd ask for a more detailed version -- there are free programs available which can simplify a cloud at your discretion, to suit your needs.

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tmassey

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I was reading up on these posts and visiting the sites and I must say I am confused so I am looking for clarification. Why would you use a point cloud and not just create a 3d model. I know I am missing something here.

What is the point of a point cloud.

cheers

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Using Revit Architecture 2012

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itsmyalterego

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Well, a point cloud can be generated with 10 minutes of laser scanning, and everything it scans in accurate to a fraction of a inch up to hundreds of yards. 

The point cloud is not your final product, it's not even a surface.  it's like a ghosting of surfaces, so that as you build your real model, you can crosscheck with the point cloud data.  If you want to know the slope of a canopy roof, or the height of that roof at any point, or the topography, or the location of tree trunks on site, surrounding buildings, without pouring through tons of cad or other references... everything is in the point cloud scan. 

It is EXTREMELY powerful, but the downside is that getting a laser scanner is outside of most firm's budgets, and you'll have to hire someone to do the scans for you, which, well, might not be an option in itself, depending on where you live.   

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tmassey

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If I am correct the point of this is to scan real objects to import them into Rev or CAD to create a 3D model or dwg.

e.g. I was renovating a turn of the century hotel..no know drawings. if the budget was there we could have scanned the building instead of hours of on site measurements and redrafting.

Is this what point cloud does?

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itsmyalterego

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yes--but instead of using a 3rd party app to turn the point cloud into a mass, it's probably easier to model the hotel with ordinary walls, windows, etc.  If your point cloud data is dense enough, such as the data you'd get from a scanner, then it'll be just as easy to interpret as a solid. 

I DO wish that revit would be able to create masses from clouds, for non-essential aspects of the scan, like the site!  and surrounding buildings not involved in construction or renovation. 

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SteJa

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you gotta re-thin that laser scanning is not identical with classic surveying, becaus you have indiscreet points!

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WWHub

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Point clouds are actually being used instead of classical surveying for a variety of uses and they can be very finite:

Here are some interesting sites: http://www.certainty3d.com/products/?gclid=CL_up9iDmqoCFQJrKgodkRGaww

http://www.xmeasures.com/?gclid=CIXK-I2EmqoCFYZrKgodkDomyQ

http://www.sparpointgroup.com/Blogs/Head-in-the-Point-Clouds/Using-laser-scanning-to-assess-tolerance-on-large-projects/

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LaserscanningEurope

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Joined: Fri, May 13, 2011
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We can suggest you to try the pointcab trial version to fix your isseus http://www.pointcab-software.com

we will present a new tutorial feed considering the initial post soon!

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http://www.laserscanning-europe.com

http://www.laserscanning-service.com

http://www.pointcab-software.com/

http://youtube.com/laserscanningeurope

http://facebook.com/laserscanningtv

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