Alignment, Persistence, Tracking - What it means on the Augmented Jobsite
We're almost through our intro to AR series. You've tried AR, brought in your BIM and now its time to see that data in context on site. How did this HVAC hologram know where it's was supposed to be?

By the end of this post, you'll understand AR concepts of Alignment, Persistence, and Tracking and other AR vocabulary terms that will make you a hit at parties or job interviews.
Tracking 101 - How does AR track its movement through space?
Whether it's head mounted or handheld AR--No matter what you’re doing, your AR device senses its movement. Like the accelerometer in your phone, your AR device has an idea of where you are and how you're positioned. And it's usually pretty accurate. But what about when you walk a distance in AR?
How good is that tracking when I walk around a site?
This is a question about the concept called “drift.” Does the device register my 10 feet of movement? Or is it a little bit off?
When you're using AR for your construction job, you need it to be reliable and accurate. In general, a purpose built device like a Hololens will have more precise tracking than your phone or iPad combine that with an application that is designed for the construction workflow, and you'll be set.
Applications for Augmented reality in Construction, like Argyle, correct for drift on the jobsite to ensure holograms are accurate, wherever you roam.
How does Augmented Reality know where to put the holograms?
This is the concept of “Alignment.” It’s also referred to as “Registration" or "Calibration."
Don’t underestimate the importance and potential challenges of good alignment. To be aligned, the AR device must understand its location in physical space--whether that’s relative to the room, the city, to the world, or to the jobsite.
In the construction context, we’re often aligning BIM holograms to the site or building.
All AR applications for construction have a mechanism for you to align to the world. So when you're researching options, ask “what do I need to do to get the hologram correctly aligned to the real world jobsite?”
Argyle was designed to solve the alignment problem on large, active, and constantly changing construction sites. Argyle's proprietary technology called Risa allows the holograms to stay aligned to the jobsite--without needing to print and laminate 2D Markers every time you update your model.
What about changing conditions or locations?
AR devices read the world around them to find itself in space, so naturally your next question is about what happens when you open the app in a new location.
What about a different room, a different floor, or even a different spot in the room?
Or what about when conditions change entirely--the wall is built, the scaffolding is removed? Or what about when the room looks completely different from the last time I opened my device in the space? Working with location changes or environmental conditions changing?
This is the idea of “Persistence” in Augmented Reality. Or-- “Is the hologram going to persist in the correct location even when I open up my app on a new space in the jobsite?"
Persistence is important when you want to be able to do good location-based AR spontaneously, in an unplanned situation and location. Like on location at a jobsite, you’ll want to be able to begin the application anywhere and quickly and easily perform the task. Argyle allows you to do this on any BIM enabled jobsite.
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