Smartphone Measuring Technology

Smartphone Measuring Technology. 

This new measuring technology claims the software to be ANSI compliant. 

Appraisers, over the past couple of years, there have been lively discussions on forums, Facebook groups, at conferences, etc., about a ‘new’ technology which allows a ‘phone holder’ to measure a structure, with that technology providing a “Sketch” or “Floor Plan” of that structure.

Some of you may have heard about one of the originating companies, Matterport, which some real estate agents/brokers use to generate virtual 3D interior diagrams and videos used in property marketing. Smartphone measuring technology evolved from that.

Until recently, I and others did not understand the difference in how the measuring technology works between the iPhone and Android phone versions. Some descriptions call this process ‘augmented reality’, or AR for short.

Jeff Bradford, owner of Bradford Technologies/ClickForms, gave a presentation at our Washington State appraiser association conference and explained the differences.

iPhones use LiDAR. In simple terms, this technology sends out pulsating invisible light streams similar to laser which bounce off items and then return to the device as ‘data points’ which can be measured and used to formulate images, from which the fairly accurate exterior or interior measurements can be calculated. Those then can be plotted onto what we know as a Sketch, or a better Floor Plan. iPhone developers have chosen to keep this feature in their phones.

Android developers, on the other hand, use a process called Photogrammerity used to generate the diagrams we use in appraising. Interestingly, a very few older Android phone models DID have LiDAR included, but the developers have chosen not to continue using that technology in their newer Android phones.

I don’t claim to fully understand Photogrammetry, so I’ll direct you to this article in Wikipedia: .

There currently about 7 to 8 different companies, including some AMCs, which are promoting measuring services using the above technology, at a cost per use. One company which uses LIDAR seems to have the most users currently. There is a turn-around time element with these services because the diagram in the phone software often must be uploaded to a server maintained by independent “off-shore” companies outside the US who employ drafters to convert the phone’s internal diagram data into a “Sketch” or “Floor Plan.” This is returned as a PDF to the appraiser via email.

But this ‘apple cart’ may be upturned if a new diagramming app from Apple takes hold, named “Room Planner.” Per another attendee in the room, Peter Vander Wall, SRA, who posted to a forum, “currently ‘Room Planner’ is available only as an API (Application Programming Interface), which is a software kernel that allows developers to create applications based on it for users like us.” This means it could be developed into a less costly Floor Plan generating application.

There’s been lots of commentary about appraisers comparing the phone-held measuring software/diagram with their own diagram based on their own measuring with traditional tapes or lasers. The consensus seems to be that the phone-held process is nearly as accurate, not necessarily 100% in all cases, but pretty darn close.

What I have not seen yet is any accuracy comparison of the two types of phone-held measuring software (LiDAR vs Photogrammetry) done on one structure, contrasted with a Sketch or Floor Plan done by a person using traditional measuring with tape or laser. That’s probably because very few appraisers own two different kinds of smart phones due to the cost!

The other aspect of this smartphone measuring technology that I’m presently unsure about is whether or not it FULLY complies with ANSI-Z765-2021. This is especially important in homes with sloping interior room ceilings, and short ceiling heights, which ANSI is paranoid about in terms of livable space – regardless of how people actually use that space! And secondly, with oddly shaped interior stairs which may not be immediately adjacent to a wall.

Some marketing I’ve seen so far with this new measuring technology claims the software to be ‘ANSI compliant’. Truthfully, that needs to be fully evaluated in the field in actual homes.

The other screwy situation about ANSI and Floor Plans, is if the appraiser does not measure the home, but instead relies on a Floor Plan provided by a secondary source, that Floor Plan DOES NOT have to comply with ANSI when the report is for conventional mortgage lending on a DESKTOP form. But when it’s a ‘traditional 1004 form’ conventional lending assignment going to Fannie Mae only, and the appraiser (or trainee) measures, an ANSI-compliant Floor Plan is required. Some non-FNMA clients demand ANSI measuring in their assignment SOW, so be sure to read that document!

Frankly, this nonsense has been compromised by the GSEs. Their original intent was that the appraiser would rely on common sources for the dwelling Floor Plan and other necessary data for DESKTOP reports. However, proper Floor Plans (as defined by the GSEs) have proven to be elusive. For HYBRID reports, the GSEs intent is to accept a Property Data Collector’s Floor Plan and written inspection data. What’s been happening is PDC reports are now being given to the appraisers for DESKTOP reports which is contrary to the GSEs anticipated process – but they are reluctantly accepting these.

It’s the old story about “follow the money.” Unintended consequences be damned. They’ll just process the DESKTOP reports regardless.

If you’re contemplating using any of the available smart phone measuring software on homes YOU MEASURE, be sure whatever you choose CAN do a proper Floor Plan. The measuring ‘app’ you want to use must be compatible with your phone. Some of the ‘freebee’ or ‘subscription’ apps only do perimeter diagrams, which may not comply with the SOW for some assignments.

But in the ‘big picture’, in the same way computerized appraisal form software, digital cameras and laser measurers have revolutionized processes in appraisers’ work flow, the same could be anticipated with this new ‘phone-held measuring-diagramming’ technology.

Dave Towne
Dave Towne

Dave Towne

AGA, MNAA, Accredited Green Appraiser - Licensed in WA State since 2003. Dave Towne on

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15 Responses

  1. Avatar Realist says:

    Much of my work is for various types of litigation/legal matters. As a result I use narrative reports and use a tape measure only. I also always measure to 1/10 of a foot. Opponents often round measurements to the closest half foot, or even foot. The more angles a house/building has – the more risk these big rounders have of under or over stated room/building sizing. Depending on the complexity of the house/building I am measuring, I may spend up to several hours measuring and Apex drawing the structure(s); probably spending more time than the opposing appraiser takes to complete an entire appraisal report. Measuring with lasers/phones/other devices are not consistently accurate/reliable enough for my personal appraisal requirements. Thorough/accurate appraisal reports have a significant advantage in litigation/legal work. I have had many attorneys state that my report(s) won the case, often without going to trial. I am not tooting my own horn, I am simply stating that I work my rear end off out of respect of for my client and for the value type as defined in the report. Over time, Judges relate hard/competent work to some appraisers. It sickens me to regularly have residential appraisers brag about how many appraisals they do in one day – even some appraisal instructors do this. I have reviewed many of these worthless hack appraisals over the decades, especially over valued refinance appraisals. Developing/using shortcuts such as electronic measuring tools, in my opinion, is not a positive change for appraising. Be skeptical about everything and don’t just fall in line with changes and promoters of change without using your brain and considering the consequences of a potential change.

    • Baggins Baggins says:

      Sure, it’s important to be committed to professionalism. But what is professionalism in the modern age of tech and where should we apply practical limitations in the pursuit of efficiency? I would say if you have found success with the simple laser tools, take several precautions. Always roll with laser safety goggles. Anywhere a laser is present should be considered like a construction area where hardhats are required, always use specialty laser safety goggles. The problem with these devices especially the mass produced items, is the aperture device and power supply hardware can become faulty of no fault of the user. Even the low frequency lasers are still noted by optometrists as being ‘relatively safe’. There is no such thing as a laser which is 100% always safe for your eyes. Appraisers may be unaware they might be holding special allowance more powerful lasers under the surveying use regulations. Manufacturers claims of regulatory compliance are not necessarily synonymous with a guarantee of a safe user experience. Be especially cautious around reflective surfaces. Thank you.

  2. Avatar VA Klein says:

    We are cautioned to not value solely on a price per square foot basis. So, while I certainly appreciate those who aspire to present what they consider the most accurate GLA calculations, most of the time it is a false precision. At what point do we adjust for size? At what point would a buyer would pay a premium for a GLA measurement that’s maybe 5% different from the “precise” appraiser’s result? Maybe 10%? Would a buyer discern value from 25 sft? Maybe 35 sft? It’s a problem because most data for comps are drawn from public sources. What was the standard for accuracy there? For the record, I don’t use the Lidar technology……still use a laser. But I feel that those who aspire to pin-point accuracy have chosen the wrong field to apply that particular skill, at least in residential appraisal.

    • Avatar Realist says:

      Good excuse to be lazy. The Appraisal Institute used to teach, and maybe still does – strive for accuracy during the appraisal process and round at the end of the process. Lazy appraisers round throughout the process, always having the potential to skew the indication of value (sometimes a lot) and defend doing so by saying we don’t want give impressions of an unrealistic level of accuracy. And of course they finish their appraisals in 2-4 hours. Then that appraisal hits the reviewer’s desk. it would be easier for me complete a new appraisal instead of untangling the mess in the appraisal under review. Thank God the vast majority of my work is non-residential and eminent domain because residential (especially mortgage) is a hot mess.

      Who said I was appraising solely on a “price per square foot basis”? Many real estate agents do this using an unadjusted “price per square foot” which is not accurate. And, it is okay to value on the price per square foot basis as long as appropriate adjustments are made.

      I’ll be sure to tell the attorneys I work for (never lost a case and partially lost only 1 tax appeal) , that I need to become more loosey-goosey and maybe I should find a new career because I strive to be as accurate as I can. The thing of it is, is that house/building size are areas in the appraisal where the appraiser can be highly accurate. I have had instructors stating that clients have sued because a subject house/building was not accurately measured.

      Fortunately retirement is around the corner.

      • How long does it take you to type the appraisal? 4 hours is plenty of time for a non complex property.

        • Baggins Baggins says:

          I spend the first four hours of my day dealing with anxiety of how crumby this industry is. Then when I’ve drank a half pot of coffee, 1-3 hours pre research, 1-2 hour drive inspect and comps, .5 to 1 hr sketch at desk, 4-8 hour free writing block, 1-4 hour analysis set, sometimes much longer. We know it’s possible to complete appraisals that fast, but we put in the additional work anyways. It’s how you run your entire career without a single insurance claim or state complaint, jumping to the front of the line in approval process, a superior more informative work product. The one I’m closing out today is like 30 hours, complex but at least something is coming in. The next one should be pretty simple, I’m anticipating an 8-10 hour set.

          Also remember when you click and go pre type sort of approach, that may be identified in forensic review and CU system analysis as being a faulty work product. It’s how a hundred thousand appraisers before us have been washed out, leaning on pre written and then getting called out for not complying with the prewritten peramiters, failing somehow to be adequately informative reliable and specific. I get sort of jealous of appraisers whom can cut them fast for like condos and high rises, but then I’d have to actually go to condo’s and high rises. Not my cup of tea. I’d rather drive two miles out into rural areas than drive twenty minutes to the city. All it takes is one single complaint or claim, be careful with the speed vs quality consideration. An appraiser pal of mine had a complaint, sought representation, and was quoted dang near $40k in legal fees.

      • Avatar VA Klein says:

        Scenario: Three appraisers measure the same structure, and not surprisingly, come up with three different results. The appraisers are you, me, and someone with one of those HMS designations.

        Who is to be believed? Me, a “lazy” appraiser doing mostly residential work, you with your sterling court record, or the appraiser with the HMS designation?

        You can debate the outcome, but who is “right”?

        When was the last time you calibrated your laser? How long have you been using your nylon tape measure? (they stretch over time). To what standard did you measure the structure?

        I admire your dedication to be as “accurate” as possible. It is certainly laudable. Has anyone ever challenged your calculations, or does your reputation of never “losing” a case make you unassailable?

        • Avatar Realist says:

          Tapes are replaced often, every 3-6 months with good quality tapes. By the way – try an experiment – take your 3-6 month old 100-foot tape and stretch it next to your brand new tape. The difference, IF at all is a mini-fraction like 1/64 of an inch. Still more consistently accurate than a electronic device, and way more accurate than the big rounders. Also, for court, I can suggest a site visit by the court to answer discrepancy issues. I have had cases where Judges actually do some investigation. I just finished 3 drainage easement cases where the judge visited the properties in question. The tape argument is a stretch. For the big rounders, the court also wonders what other parts of the appraisal they are “short-cutting” – and they are always plentiful and easy pickings in my experience.

          • Baggins Baggins says:

            My pocket sized 100 ft thin metal tape finally just broke off the tip after 20 years of reliable service. Hope I can still get another one. Duct taped it in the meantime, and it’s now my designated backup, lol.

  3. I use a 30 ft Stanley tape measure, Stanley is the only brand I have found that does not chop off your finger if it spools back in to fast. And I carry a laser measure for condos and measuring garages. I cant see the laser very good outside and its hard to measure corner to corner at weird angles. I used to own a Matterport camera, the technology is there, I just dont think its practical yet.

  4. Avatar Koma says:

    If it ain’t broken… I still use a reel tape measure. Tried a laser a couple of times about 10 years ago, but with all the different materials used in housing it just never would work precisely. IDK maybe it was me? Not too much longer until retirement, so I’ll keep using my trusty tape measure.

  5. Avatar Pat says:

    The Board and legislature made it very easy to get the CORRECT SQ FTAGE OF A CONDO in Virginia. The GLA is a part of the deed as well as Master Condo docs which are also recorded as part of the legal description. If appraisers in Virginia are measuring condos they are probably reporting inaccurate living area. It is the Condominium Act of 1973.

    It was based upon California’s Condo Law.

  6. Baggins Baggins says:

    Scenario, unreliable public records, two different size estimates within the year, disconcerting differences of home size opinion. I stepped in there with a standard 100 ft vinyl, adhered to local jurisdictional rules which indicate garden level is not basement, free drew a 2.5k quad level in about 10 minutes flat, another half hour at the desk for a finished sketch which properly blocks out every different level, and addition areas.

    Skipped the privacy invading technology. Skipped the cloud hosting with overseas data security issues. Skipped the ethical concerns of being utilized like a pawn so tech companies can monetize 3d scanned models of peoples homes and their subsequent ‘home fingerprints’ in globally accessible data systems. Skipped the ewaste, environmentally damaging pollution and material waste associated with relatively short life of both the hardware and software applications which inevitably in a system of planned obsolescence, have consumers running back for more tech items like all the time. Set the record straight for a concerned home owner.

    Then I put the 15 dollar tape measure back in my backpack to use another day. Had a fine steak and beer for dinner with my cost savings. Utilizing lidar or any other 3d modeling tech is equivalent to taking a few million photos of peoples homes. And those data files delivered to third party companies whom return just a 2d sketch, the files carry a lot more data and detail than is necessary for such a simple sketch effort. It’s clearly overkill and too much.

    Personally I would not want a home which has ever had it’s interior spaces documented and 3d scanned in this manner. From the privacy implications, to the ewaste, to the data brokerage and subsequent ancillary monetization, no clear policies for data retention which certainly result in an unlimited data shelf life, to the basic human interactions, respect for privacy. For everyone using this tech, do you even bother to ask the home owner if they were o.k. with this? Did they even have a choice what method and volume of documentation was utilized?

    Let’s see here, post a photo of rivers of leeched plasticizer and heavy metals pollution set amist literal kilotonnes of discarded ewaste, or perhaps just the free sketch draw to illustrate a better more simple more environmentally friendly and privacy respecting method. Besides, lasers and these millions of high volume high frequency waves reflecting and refracting off of everything can literally cause you to go blind and may cumulate eye damage over time. Don’t accidentally twist the phone towards you or shine it into a mirror or off glossy glassy surfaces while you’re running that app, burn your inner retina components out, geesh. If you actually use this sort of tech I would seriously suggest a pair of very high quality laser protection glasses, and bring a few extra pairs for the home owner too, and their pets. Then you can really not just play the part of a mad scientist, but look like one too. Toss on a white lab coat for that extra authoritative presentation.
    Is your phone pushing 900 nm range, more, less? Personally I’d want a lot more data about the app, the frequency, the phone, the safety, before jumping on board with anything lidar, especially right there in my hand. Articles on the dangers and evolution of lidar tech go back seventy years. It’s not new, and there is a good reason the applications were limited to aerial nautical and military. Be careful with the advanced tech, it’s not a toy and lasers of any frequency and range are no joke.


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Smartphone Measuring Technology

by Dave Towne time to read: 4 min