Facade 3d scanning for retrofit purposes

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karlis
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Facade 3d scanning for retrofit purposes

Post by karlis » Thu Aug 31, 2017 8:13 am

Hi everyone,

I am just starting to learn about the possiblities of 3D scanning, so the question will probably be kind of basic, but you got to start somewhere, right?
The need - We are in need of 3d facade models for prefab building element production (starting from 3d measurements, to design (Revit), to factory production). We need to know the flattness of wall in both horizontal and vertical axis of facade. Maximum height of facade would be approx 9 stories (so about 30m).

The question - What would be the best method and system to do this? What would be the price ranges we should be looking in to? Also what would be the precision of that 3d facade model (we have had some outsourced help with this and the precisions was something like +- 2cm, not good!).

At this point we are looking in FARO Focus serie of units, they all seem to be up to the task, but I would be really grateful for some expert insight on this topic!

There is also photogrammetry, but I suppost that method won't be suitable for this task.. right?

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Re: Facade 3d scanning for retrofit purposes

Post by Formula1982 » Thu Aug 31, 2017 9:12 am

My preference would be for a Trimble SX10, Leica C10 or Leica P40 for the data collection as i'd trust those the most to get very clean, accurate data.
I assume you're looking at hiring a company to perform the survey for you, rather than doing it yourself?
The accuracy and quality of the data if it was done with a good time of flight scanner would be high, but the accuracy of the model is what you're interested in, and that's more tricky to quantify.
You need your design models in Revit, but as I understand it that's not the best type of modelling if you also want to know things like deformations and flatness. Revit models tend to standardise the features because that's what you need in a design usually. Flat walls and floors etc.

If I were doing that job, i'd scan it with an SX10, have it modelled in Revit to the specifications I needed ultimately, then as a separate exercise i'd do an analysis between the model and the point cloud for deviations. i.e. looking at where the point cloud surfaces go beyond a set tolerance away from the modelled surface.

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Re: Facade 3d scanning for retrofit purposes

Post by karlis » Thu Aug 31, 2017 12:34 pm

We would like to buy the 3d unit to do it ourselves, because we also do histirical building retrofits as well ar architecrutal designs for retrofits etc., so there would be more use for the "camera".
Very interesting information about the Revit part and deviation analysis! Thanks for that, I will think about how and if we can do it this way.
Thanks!

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Re: Facade 3d scanning for retrofit purposes

Post by tbwester » Thu Aug 31, 2017 1:17 pm

used c10 you can get for cheap, that would be my first choice. The c10 will be a bit slower for internal scanning work though.

You'll need a bit of training to make sure the registration is perfect.

Like mentioned above, its very likely that the 2cm of error on your previous project was added in the modeling portion of work. You should do the modeling in-house if you want it to be perfect, or even design right from the point cloud.

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Re: Facade 3d scanning for retrofit purposes

Post by richard_m » Fri Sep 01, 2017 10:06 am

karlis wrote:
Thu Aug 31, 2017 8:13 am
I am just starting to learn about the possiblities of 3D scanning,
Hi, and welcome,

I think you're kinda aware of the issue here, the project you're proposing is a potenitally demanding one and, more importantly, the consequences of getting it wrong are very high as the cost of panels hanging from a crane several floors up that fail to fit are very high in delay costs, remanufacturing costs and reputational costs. With the benefit of many years of experience if I risk-assess such a project then the risk of failing to achieve what will be tight tolerances is medium but the concequence of this potential failure is high. Add the meduim likleyhood to the high concequence and does this sound like a good project to be learning a new industry from forum posts and youtube videos?

If this is a big market for you (or will be) then you need to hire an experienced 3d suveyor with both laser scanning and construction experience and good 3d CAD / Revit skills. Money very well spent, also its easier to hire a scanner than such a professional and I would budget this way around.

Alternatively it might be an idea to partner with a survey company that can prove relevant experience and relevant insurance and ask them not for a product but for a service, i.e. work alongside then to learn from them their approach to undertaing this, with a view to doing such work in the future.

Of course Faro (and others) will be happy to sell you a scanner on the basis of "its easy to use.." and point you to you-tube. If you are committed to going down this route then budget in and insist on having extensive training (good luck) and most importantly for the future of your business speak to your insurers about the liability of undertaking primary as-built design dimensions with little or no training / experience to do so.

Generally, a Faro could work but you'd be better off with a Time-Of-Flight scanner (such as the Leica suggested) to get clean data at that range, bearing in mind the building is 30m+ high and you'll need to scan from 30m+ away.

Also, I fully agree with the above post the Revit is not really a design tool, its very good at fitting 'stuff' to pointclouds for pretty visualisations and asset management but it does this using lots of averaging and best-fit procedures that would blow your tolerances almost immediately and would be difficult to QA.

Richard.

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Re: Facade 3d scanning for retrofit purposes

Post by pbashiri » Mon Feb 19, 2018 5:11 am

That`s what I have used for the following job. I used our ZF 5016 to scan the whole exterior building and Auto Cad to generate as built situation of the canopies and fins. I shall say the client couldn't be more happier about the result.
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Re: Facade 3d scanning for retrofit purposes

Post by berdindc » Mon Feb 19, 2018 1:35 pm

richard_m wrote:
Fri Sep 01, 2017 10:06 am
karlis wrote:
Thu Aug 31, 2017 8:13 am
I am just starting to learn about the possiblities of 3D scanning,
Hi, and welcome,

I think you're kinda aware of the issue here, the project you're proposing is a potenitally demanding one and, more importantly, the consequences of getting it wrong are very high as the cost of panels hanging from a crane several floors up that fail to fit are very high in delay costs, remanufacturing costs and reputational costs. With the benefit of many years of experience if I risk-assess such a project then the risk of failing to achieve what will be tight tolerances is medium but the concequence of this potential failure is high. Add the meduim likleyhood to the high concequence and does this sound like a good project to be learning a new industry from forum posts and youtube videos?

If this is a big market for you (or will be) then you need to hire an experienced 3d suveyor with both laser scanning and construction experience and good 3d CAD / Revit skills. Money very well spent, also its easier to hire a scanner than such a professional and I would budget this way around.

Alternatively it might be an idea to partner with a survey company that can prove relevant experience and relevant insurance and ask them not for a product but for a service, i.e. work alongside then to learn from them their approach to undertaing this, with a view to doing such work in the future.

Of course Faro (and others) will be happy to sell you a scanner on the basis of "its easy to use.." and point you to you-tube. If you are committed to going down this route then budget in and insist on having extensive training (good luck) and most importantly for the future of your business speak to your insurers about the liability of undertaking primary as-built design dimensions with little or no training / experience to do so.

Generally, a Faro could work but you'd be better off with a Time-Of-Flight scanner (such as the Leica suggested) to get clean data at that range, bearing in mind the building is 30m+ high and you'll need to scan from 30m+ away.

Also, I fully agree with the above post the Revit is not really a design tool, its very good at fitting 'stuff' to pointclouds for pretty visualisations and asset management but it does this using lots of averaging and best-fit procedures that would blow your tolerances almost immediately and would be difficult to QA.

Richard.
Very well said. We have done a few of these over the years, mostly with the C10 but before that with the Leica 3000. I certainly wouldn't use the FARO.

I would echo the comment on the "risk/reward" potential. These are challenging jobs to get right to begin with -- add to that the accuracy requirements and the cost/delay/risk of getting it even slightly incorrect, having to defend you work, having confidence in the data in the first place....

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