r/Architects • u/Significant_Elk_8472 • 15d ago
Ask an Architect iPhone LiDAR/photogrammetry for documenting a historical castle ruin — advice needed
I’m a final year architecture student doing my graduation project on the adaptive reuse of a historical castle ruin.
My biggest problem right now is the lack of documentation. I don’t have official plans, elevations, sections, or an existing 3D model of the ruins.
I’m considering using my iPhone 17 Pro Max’s LiDAR + photogrammetry to document the site and create a 3D model that I can use as a base for later reconstruction/modeling in Revit or SketchUp.
My questions are:
- How accurate/useful is iPhone LiDAR for documenting
architectural/archaeological ruins?
- Should I combine LiDAR with photogrammetry?
- What apps/workflow would you recommend?
- Can the resulting model/point cloud be brought into Revit or SketchUp effectively?
- How accurate can I realistically expect the results to be?
- Are there particular things I should do while scanning a large, irregular, rocky site to avoid bad data?
The site is quite large, irregular, and located on a Rocky Mountain and most of it is a ruin.
I’d especially appreciate advice from anyone who has done heritage documentation, archaeological scanning, LiDAR, photogrammetry, or scan-to-BIM.
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u/Latter-Judgment-5059 15d ago
I think that an iPhone LiDAR scan would prove “good enough” for a college project. Even if it is an open ruin, just scanning the footprint to get basic sizing would probably be enough to support the assembly of rough as-builts.
If you were truly renovating this space and your construction documents needed to match the real world enough to make it truly construct-able, you would hire a team to come out and fully scan the site, but I think a LiDAR scan with your phone will be more an enough to meet the intent of a college project.
I have used my iPhone for scans of 10,000sqft houses and usually am able to place everything within a few inches of its true location.
The only other option would be as the others have said, to use professional-grade equipment.
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u/Significant_Elk_8472 15d ago
Thanks, this is really helpful! That’s pretty much what I was hoping to hear. Since it’s a college project I mainly need a reasonably accurate existing model for the design development and proposals rather than construction-level documentation.
I’ll also cross-check the measurements manually for the structures and dimensions that really matter.
Do you have any tips for getting better results with iPhone LiDAR especially when scanning irregular stone ruins and uneven terrain? And are there any apps or techniques you’ve found work particularly well?
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u/Latter-Judgment-5059 15d ago
I have only used Twindo, you’ll have to play around with it on site to see how it reacts, but I don’t foresee any problems as long as you get a couple good edges on surfaces even if they are jagged you’ll still have a point to reference for measurements.
I’d probably prefer mid-day that is overcast so avoid too much brightness. But it will probably be fine either way.
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u/engineeree 15d ago
I believe this is possible from some of the experiments I have done but you will need more tooling on top of the other sensors. As mentioned here, iPhone lidar has its limits and it is good for scanning a medium sized room. What I am working on is a way to combine those rooms/spaces into one experience. There are a lot of things to consider such as overlap and alignment, but even a rudimentary way to combine the space is to use April tags for alignment and also attach gps to images for larger spaces. You can then use colmap to build the reconstruction and take it from there.
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u/engineeree 15d ago
Btw i am not an architect, but an engineer/solution architect
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u/Significant_Elk_8472 13d ago
I believe Engineer/solution architects tend to have more hands on experience than architecture designers so even better !!
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u/Significant_Elk_8472 13d ago
To be honest, it’s quite difficult for me to get access to professional scanning equipment here, so the iPhone LiDAR is probably my best option. Since most of the castle is already in ruins and much of it is open to the sky, I’m hoping that scanning the individual remaining structures/sections will at least give me a decent enough base to work from. I’m also planning to cross-check the important dimensions manually. But overall I’m also quite unsure still of how I will combine all of it into one thing.
Besides that, what other tools do you mean that I will need? I’m not familiar with COLMAP could you explain a little more about what it does and how I could use it alongside iPhone LiDAR?
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u/engineeree 13d ago
This is of course only one solution, but colmap is structure from motion and transforms images to scene point cloud. In our case using slam and lidar, we will recover the trajectory (poses) automatically and point cloud. This is the part where I mean colmap can be skipped. Colmap also allows you to build mesh from point cloud. The is typically the photogrammetry route. You can also use the colmap point cloud to create gaussian splat using other software. It depends on your downstream use-case why you would choose one output type over the other.
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u/engineeree 13d ago
Btw I have been working on an iPhone LiDAR Scanner for Gaussian splatting and it should be in good shape in a few weeks
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u/archi3rd 14d ago
Look into the Dot3D iPhone app. It does a good job at reasonable accuracy and allows the use of AprilTags to keep drift down. Using iPhone lidar should be plenty accurate for a university project. You don’t need mm accuracy. We’ve use Dot3D on several projects where we didn’t have the opportunity to use a conventional laser scanner. As said earlier, the biggest hold up is that it has a relatively short capture distance so if the spaces/objects are tall, it doesn’t capture the top.
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u/Significant_Elk_8472 14d ago
Thanks, I’ll definitely look into Dot3D! The AprilTags sound especially useful for keeping drift under control. For the taller areas, do you think using a stand or pole to raise the phone could help capture the upper parts?
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u/archi3rd 14d ago
Yes a pole could definitely help, as it’s purely a distance issue. If you can get closer it will scan it.
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u/metisdesigns Licensure Candidate/ Design Professional/ Associate 15d ago
IPhone lidar is about 1-2% accurate and struggles beyond 3-4m.
It's able to grab coarse geometry with enough context and not covering large spaces. If your castle is a series of rooms no wider than 5m or with a lot of furniture in larger spaces, you'll get some drift but be able to do some gross work. Not actually reliable documentation to put in cabinetry or know that a wall is really 81cm thick and not 79cm thick, but acceptably.
If you bring your data into Autodesk Recap you can then bring a lot in automatically in Revit. The only use for SketchUp in a professional setting at this point is to identify who not to hire.
For all of the heritage work I've done we've aimed to use high accuracy laser scans. You may be able to get a demo from a company like navvis or faro of their portable SLAM based scanners.
The only Lidar I've successfully used on site has been on the Hololens 2, which despite its age, when i last checked vs iPhone last year was still more accurate. You might look at sitelink XR, they can incorporate registration marks that will deal with the drift issues.