Brett Casson: Leica BLK360 Field Test on a Residential Property

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Brett Casson is an Autodesk Sales Development Executive serving the Architecture, Engineering, and Construction (AEC) industry. For those of you who have read the latest Autodesk book, THE FUTURE OF MAKING, Brett and Autodesk Technologist, Shaan Hurley are featured in the first chapter where they scanned bamboo structures at Green Village in Bali. Brett recently filed this report with the Autodesk Reality Capture team that he titled: "Leica BLK360 Field Test — Residential Property."


Having begun laser scanning almost fifteen years ago using a Leica ScanStation 2 powered by a generator and requiring the most powerful laptop of the time to control it, and working in the deep dark railway tunnels under Sydney, you could image my astonishment at the simplicity of the latest generation terrestrial scanner, the Leica BLK360. It's not the size so much as the functionality — which I'll get to shortly, and the vast array of applications for which this scanner could be used. In my case, it was a residential property that has been earmarked for redevelopment and requires an extensive, detailed survey both external and internal to the residence.

Detailed surveys (i.e., measured building surveys in some geos) have up until recently been undertaken using traditional survey total stations and traditional survey traversing techniques. Using terrestrial scanners to undertake these surveys was seen as cumbersome, time consuming, and overkill. As the form-factor of these scanners has progressively gotten smaller, battery technology has also progressed (enabling a full day's scanning), and registration algorithms (i.e., mathematical positioning of individual scans) have been logarithmically advancing. So now, using a terrestrial scanner is now a more than viable solution. In parallel, municipalities and councils generally have strengthened the requirements for development of residential and commercial properties. The information now required for a development application or planning permission is so rigorous that including a combination of adjoining information, slope analysis, energy performance, and in the case of Australia, bush fire (wildfire) considerations, is necessary. Therefore the need for rapid data collection, and most importantly an extensive data set of the site in question, is now less aspirational and more mandatory. Lastly, the economics too need to be compelling, as detailed surveys require rapid data collection, rapid processing, and a rich and robust data set for the client to begin a compliant design in the shortest time possible.

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The survey required was a typical land parcel in Sydney of around 600m2 in size (shaded blue), not overly vegetated, and the site sloped from the rear of the property to the street. This survey of both internal to the residence and the external site survey would typically take around 6-7 hours using traditional methodologies and technologies. Using a terrestrial scanner to undertake this survey, I used the "outside to in" methodology that surveyors have lived by for generations. Essential surveying the extents of the property and then surveying the internals. Mathematically, this would produce the most robust result. Additionally I would not be using traditional traversing using survey targets, rather letting ReCap Pro Mobile register the results as the site survey progressed.

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One of the first things that surprises the user of the BLK360 is the ease of connection to the ReCap Pro Mobile iPad app. Simply press the only button on the scanner, and a wireless hotspot is created. Connect the iPad the BLK360 network, open the ReCap Pro Mobile app, and that is pretty much it. To undertake the individual scans is fast, around 4-5 minutes including color imagery and you are done. This is important as stated earlier since the economics of using a scanner here need to be compelling. Additionally, with a shorter scan time than traditional scanners, the user can undertake more scans, capturing more information and making life easier for ReCap Pro Mobile which makes life easier when using a cloud to cloud registration process. The scanner performed flawlessly with the external property to the residence completed by mornings end surveying the entire site and the adjoining features and adjoining properties. In some cases where ReCap Pro Mobile could not register or resolve the positioning between existing scans and new scans, the ReCap app splits the screen and the user then gives guidance by selecting common faces (walls etc.) between the two scans. It sounds complicated, but in practice, it works elegantly.

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Similar to the desktop app, when the software is confident of a result, the user accepts the registration and moves on to the next scan. Another process that streamlines the survey is that when the scans are being synced between the scanner and the iPad, the user can pick up the scanner, position it in the new scan location, and press "New Scan" on the app. ReCap Mobile Pro will continue to register the existing scans while the new scan is being captured. The time this saves cannot be understated.

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Battery life on the scanner is extremely good. That said, I would suggest having four batteries (the scanner ships with two) to ensure that you will get a full day's scanning in. An additional observation was that once the scanner battery reaches 15%, then scanning comes to an abrupt halt. I am assuming that this is the threshold that Leica has placed as a failsafe as the scanner is non-tethered. Additionally, I would suggest an external power pack for the iPad as using the wifi all day will use a lot of energy. This again will ensure a full day's scanning.

Internal scanning as you can gather is really the sweet spot for this unit. The speed and accuracy in which you can scan internally is where one could imagine, the majority of the use cases for his scanner will be met. Internal scanning took just over an hour for 8 rooms, from front to back. I used a new scan group to differentiate between the external and internal. This is good survey practice as if there are any errors or issues with either external or internal then these would be separated.

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Common scans were also undertaken in approximately the same positions at for the internal and external scan groups at both the front and rear of the residence. This will greatly assist ReCap Pro desktop in resolving the mathematical positions and the creation of a robust data set. In the office, simply open ReCap Pro desktop and when you select "New Survey," choose the option to download from mobile device and the scans from the BLK360 will be an option. Just ensure that you have downloaded and installed Apple iTunes.

The scans will then sync to ReCap and the option then for me was to register the two scan groups by selecting common points in the common scan between the external and internal scan groups.

ReCap then undertakes the normal indexing process, and the resultant point cloud is then displayed in the software. My initial observations of the data are that the range is particularly good with usable data up to 50m, and noise at range is particularly low with the walls of the adjoining properties looking particularly clean. An Autodesk Revit model of the existing and new development is being prepared.

The Leica BLK360 combined with the ReCap Pro Mobile app will change the AEC industries perception of 3D capture. This will in time, truly democratize laser scanning. I would also imagine that other 3D scanner manufacturers are now looking at BLK360 as the standard for small form factor, survey accurate scanners. There will need to be some caution however. The scanner most certainly has very specific use cases, as with all scanners. If using in a construction or monitoring environment or a use case where accuracy is paramount then existing survey control should be used. Due to the small size of the unit, environmental factors will come into play in certain scenarios including days where the wind strength is above normal. I also like the fact that Leica has paid homage to the Wild T2 theodolite case known as the "bullet" in creating the BLK360, recognizing the important role that surveying instrument played in history. I believe the Leica BLK360 could in time have a similar impact by truly bringing surveying and 3D data capture to the masses.

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Thanks, Brett.

Reality capture is alive in the lab.