Augmented reality for infrastructure: a first step

Augmented reality (AR) is for sure a hot subject.  Several AR applications are already available on smartphones: real estate, tourist info, restaurant/shop location and reviews, subway stations location, games, etc.  It is just beginning, as AR technology could be leveraged to many more areas – imagination is the only limit.  Of course, one application area of high interest for us is infrastructure.

Potential applications of augmented reality for infrastructure are also numerous:  Here are a few (see images below): buidling site monitoring, underground infrastructure visualization, identification and query, etc

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I am convinced that if you had a basic AR system  for infrastructure that you could use on your smartphone, you could think of many more applications.

The main difficulty with augmented reality is registration: the capacity to display the 3D model information at exactly the right location on display, with respect to the real objects.  It is important: for instance, if you want to know the exact location of a damaged pipe underneath the ground surface (because you need to excavate and fix it), you would like the virtual pipe to be displayed just on top of it, on the ground surface, and not floating in the air somewhere around you.  For accurate display of the pipe to be possible, one thing we need to know is the exact user position and orientation (well actually what we need to know is the exact position + orientation of the mobile device used for augmentation).  If we have that info, AR is easy.  Unfortunately, that information is very hard to obtain with accuracy.  And if it is only approximate, augmentation will also be approximate.  A rough estimate of position and orientation is easy to get: GPS and compass provide a rather good approximation.  That is what the commercial AR applications rely on.  As a consequence, they are not very accurate.  See an example: the Wikitude AR browser:.

As you can see, the model is displayed in the air, kind of "floating" and does not accurately track the device orientation.  Note that the user moves the device very slowly.  My guess is the result would only be worse if he was moving it more quickly.  The reason is the sensors the app relies on to measure its position and orientation: GPS, accelerometer, and compass.  Those devices are not very accurate, so is augmentation.

For some types of applications (e.g. tourist information), that sort of accuracy is sufficient.  But for infrastructure engineering, augmentation has to be displayed with much more accuracy.  If you want to get information about a fire hydrant, you probably want to make sure the information you get is related with that hydrant, and not the drain next to it.   The accuracy at which we can measure the position and orientation of an augmentation device is a major problem in augmented reality research, and prevents the development of serious AR applications.  Note that researchers in the AR world spend a lot of energy trying to solve that problem, but until then, we need to find (temporary) solutions.

Our team has been working on the problem for a while.  What we thought is instead of trying to track position and orientation, why not make the problem simpler?  Position is by far the hardest part to measure with accuracy, so let skip that – let’s assume the user does not move, but simply rotates around.  (I know, that is quite a constraint, but let’s assume that for now).  If we know the user location and we know that he stays at that location, all we have to measure is his orientation.  And that is much easier to measure with accuracy.  Now if you stand at a specific position and all you can do is turn around, what is your perception of the world?  It turns out the world becomes a 2D image, in the form of a 360 degree panorama.  So why not augmenting panoramas instead?  After all, there are plenty of panoramas around...  (think of Google Streetview).

So we developed a technique for registering and anchoring a 3D model to a panorama with high accuracy, and used it to develop 2 prototypes: one that runs on the desktop, another one on a tablet.  The desktop version can be used to view infrastructure in its real world context, from a remote location (e.g. your office).  Check the video below.  In the first part, we display underground infrastructure through the ground, and the user can click on individual elements of the model, to get their attributes (which may be stored in the model, or in a database).  It could be used for instance for planning site visits.   In the second part, we show the use of the method for viewing infrastructure before it is built, from various positions (by moving to the next panorama)



We thought that was a nice prototype, but what we really wanted was an application for the mobile user.  So we wrote another prototype, that runs on a tablet.  Here is how it works: the user gets to the area that he wants to augment.  Let say his tablet is equipped with an orientation sensor, as well as a GPS.  So the system first gets the GPS location and uses it to (download and) display the closest panorama.  Then, the system will overlay the 3D model to the panorama (the anchoring step has to be done beforehand, but needs to be done just once per panorama).  The system simply gets the current tablet orientation (from the orientation sensor) and displays the panorama in the same orientation.  From then on, the user can use the tablet as an “aim and shoot” device: to get information about a specific object, he aims at it with the device’s crosshair.  See the video below:



In those prototypes, really what the user is augmenting is a panorama.  So that is not true augmented reality.  But as you could see, it offers very stable and accurate augmentation (the model sticks to reality, without any jitter).  So the user can rely on the data: by clicking on an object, the displayed information comes from that object, not the one just next to it.

That’s only a first step!  Research in the field of augmented reality will come with better solutions for user tracking, for instance using computer vision.  But in the meantime, panorama based AR is a very good compromise!

Update: Dec 14, 2011:

Want to see more?  Dont miss my other post on augmented reality for underground infrastructure!

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  • This is very interesting.  I  am also studying the intersection of GIS and AR; I am a Ph.D. candidate at the Centre for Advanced Spatial Analysis at UCL and this is the topic of my thesis.  You mentioned at the beginning of your blog post how hard it is to use AR with GIS data, and I know exactly what you mean.

    Your blog is very interesting, and I am really looking forward to reading more and learning more about your work.

    SH

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  • This is very interesting.  I  am also studying the intersection of GIS and AR; I am a Ph.D. candidate at the Centre for Advanced Spatial Analysis at UCL and this is the topic of my thesis.  You mentioned at the beginning of your blog post how hard it is to use AR with GIS data, and I know exactly what you mean.

    Your blog is very interesting, and I am really looking forward to reading more and learning more about your work.

    SH

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