Page T2.2 . 17 September 2003                     
ArchitectureWeek - Tools Department
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  • Tools for Field Surveying

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    Tools for Field Surveying


    Two companies that make such devices are Hilti and Leica. These devices will measure up to 650 feet (200 meters) and are accurate to within an inch per 100 feet (0.8 millimeters per meter) of distance. They fit in your pocket and operate on two AA batteries. These are especially helpful for measuring vertical distances such as to ceilings or exterior soffits.

    From Measurement to Plan

    It is common to complete an exhaustive field survey only to realize, after you're back in the office, that you are missing a dimension or two. Or maybe you can't remember what a dimension refers to. This is why a video camera can be a great aid. If you do overall panning of each room and shoot video while walking around the exterior, you can often make educated guesses later on about the distances in question.

    It is also helpful to place a yardstick leaning against a wall to provide a graphic scale for your video. Digital still cameras can be used to create elevations if your CAD software allows raster image input.

    Better yet, use a video camera that also takes still photos, so you can have both formats from a single device. It's also helpful to take a tape recorder so you can dictate notes about the images you are photographing.

    Higher-Tech Options

    Some architects try to eliminate the "back-to-office, missing-measurements" problem by taking their laptops into the field and constructing drawings there. This can work if you have a clean, empty, conditioned space and can set up a desk for yourself without pressure to leave by a certain time.

    Unfortunately, conditions rarely offer that convenience. More likely, the space you plan to remodel is a dusty, unheated, makeshift storage area, where you're allowed to stay only a limited time.

    So, rather than your laptop, consider taking a less cumbersome personal digital assistant (PDA). PDAs are much easier to carry around and work with in the field. They're also useful for job site inspections and punch lists. Back in the office, you can download the data to a workstation without intermediary paperwork.

    PDAs are also powerful enough to run CAD programs. PocketCAD works on handheld Pocket PCs, which can connect to laser measuring devices to import the distances you just measured.

    A newer PDA CAD program, ZiPCAD, is specifically designed for architectural field surveying. It works on any Palm-compatible handheld device, and CAD data can be both imported and exported as DXF files. It is a simplified yet elegant CAD program, and this equivalent of a digital sketchpad gives you just about everything you need to layout a quick floor plan to work in tandem with your main CAD program back in the office.

    Never Mind the Plans

    There are yet higher-tech systems that bypass plan drawing altogether. Photogrammetry is the science of measuring distances from a photograph that was taken from a known station point with a known focal lens. It takes some effort to learn, but if you can master a program like PhotoModeler, you can make quick work of field surveying.

    In the field, you take a few measurements and a series of photos; then in the office, you calibrate the images in PhotoModeler. The software creates a scaled 3D model of the building or space.

    Unfortunately, you may spend twice as much time working with the software as you normally would for old-fashioned measuring. The process will undoubtedly get easier over time as the software improves. In a few years, this photo modeling technique may be the way we all do field surveying.

    One last "super-tech" solution can give very detailed CAD information. You might use this, for instance, on a Gothic Revival church restoration project for which you need not only room dimensions but also scaled drawings of ornate column capitals.

    The Cyrax 3D Laser Scanning System from Cyra Technologies, Inc. creates a 3D "cloud" of data points from a given station point. By merging all the cloud data from various station points, both inside and outside a building, you can create an XYZ database of the building or space. You then extract from that 3D cloud any level of detail, from schematic plans to full 3D details of column capitals.

    Quantapoint is an service available in the northeast United States that does this data collection for you. The company uses a 360-degree rotating laser camera that shoots a beam 125,000 times per second to the surrounding surfaces. The Quantapoint service can be quite affordable, particularly if you compare the cost to the hours required to do the equivalent job yourself.

    Regardless of which tools and techniques you choose, it's important to remember that the quality of results of field surveying is only partly dependent on the technology you use. Even if you have the best tools available, you still need to apply common sense to achieve maximum benefit.

    Discuss this article in the Architecture Forum...

    Evan H. Shu, FAIA is an architect with Shu Associates Inc. in Melrose, Massachusetts. He is a contributor to publications such as The Architect's Handbook of Professional Practice and Architectural Record and is publisher and editor of Cheap Tricks, a monthly newsletter for DataCAD users and computer-using architects.

    This article was reprinted from the April 2001 issue of Cheap Tricks Shu Associates Inc. with permission of the publisher.



    ArchWeek Image

    High-tech assistance for architects doing field measurements is available with 3D laser scanning.
    Image: Eos Systems and Quantapoint

    ArchWeek Image

    Laser scanning systems can give varying degrees of accuracy, depending on the purpose of the documentation.
    Image: Quantapoint

    ArchWeek Image

    ZipCAD is a new PDA-based CAD system to aid architects in the field.
    Image: ZiPCAD

    ArchWeek Image

    PhotoModeler uses photogrammetry to convert a series of photos into a detailed 3D digital representation of a building.
    Image: Eos Systems

    ArchWeek Image

    Quantapoint offers a range of services that can provide both traditional orthographic CAD drawings and 3D modeling data.
    Image: Quantapoint


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