A while ago Matia Grossi, an IMS research analyst, said: "Geotagging, or marking photos with precise location information, is poised to move into the mainstream. Today, camera and cell phone makers are exploring ways to support geo-tagging in their devices."

How long ago do you think that was said? Four years? Five? In fact it was reported in March 2008. That's how fast and how far geotagging has come since then. It has grown to be a fairly commonplace element of mobile devices, including smartphones, as well as location-sensitive mobile apps.

Only slightly more recently, in May 2008, Visiongain predicted that geotagging was poised to become "the next killer wireless application". Visiongain is a consultancy to a number of industries, including mobile. It is also a sort of research think-tank.

The report includes analysis and forecasts from 2008 to 2013. It's 72 pages long and not cheap, but interested parties can buy it here. It addresses the important issues surrounding geotagging, including the crucial question of how to make money from it.

The geotagging primer

Geotagging, also known as geocoding, is the process of adding geographical identification data to various media. Its biggest growth area is online and mobile media in the form of navigation apps and location-based services (LBS).

It is mostly used to tag photos or images of a certain location. However, says Visiongain, it "clearly has potential beyond this into the realms of mobile search, mapping and advertising."

Visiongain promotes its reports with teasers: "How can you utilise it within the marketing mix of your company? How can you make the most from mobile geotagging? You must be aware of this technological development today."

The increasing use of handsets as mapping and navigation tools, coupled with the spread of mobile advertising, Internet and search applications, has created an exciting revenue opportunity, according to Visiongain: "A revenue opportunity you should be capturing."

As the geotagging market expands and new services grow, the first-in players will have an edge over late-comers. There are already a number of devices and apps offering very sophisticated geotagging services.

With developments occurring as they have since 2008, the issue now no longer appears to be whether or not geotagging can be made to work widely and easily. Rather, it is how many business models based on the current range of offerings can prove to be viable in the longer term, beyond the "trend" stage.

GPS is currently the basis of most geotagging. "There is no doubt that GPS will become the technology of choice for mobile LBS," says Visiongain. "Once a clear geotagging technology emerges that works with all GPS mapping applications and is user-friendly and available to all, geotagging will take off."

The company adds that the growth of GPS in mobile is key to the future of geotagging. "The spread of GPS, coupled with the huge improvements in the quality of cameras on handsets, means that many users have now bought into device convergence - their phone is also their digital camera and their MP3 player, and much more besides. The astronomical success of the iPhone is testament to this."

Limits on geotagging

How long before the whole world is geotagged? The short answer is: "A long, long time yet." The deeper answer is that it will never all be geotagged.

To arrive at the short answer, consider that it would currently take at least months and probably years to geotag every point of interest in just one big city and its surrounding area. If every smartphone and digital camera user were to start geotagging right away, there would still be inconsistencies in standards and parameters needed for a global system.

There are also the physical limitations. Bandwidth is one. AT&T in the US has been criticised for the jams it experiences in its iPhone data traffic. Geotagging uses images. What's the current quip? "A picture is worth a thousand words but uses up more bandwidth than three thousand."

There is also the physical problem of constructing, accessing and maintaining the giant databases and even the storage volume needed to geotag "everything".

As for the deeper answer, theoretically it would only be possible to geotag everything in a static world. That is not the world we inhabit, which is where life is dynamic and change is natural. Landmarks are erected and then demolished. Businesses come and go.

The deeper implication of this is that geotagging should be a never-ending process. That means never-ending business for the successful players if it geotagging can be made sustainably profitable.

The what and the how

What should be geotagged seems clear enough to Dr Tyler Bell, leader of the Yahoo! Geo Technologies product team. Asked if it would be possible to geotag all the content currently available online, his responses is simple and direct - we don't need to.

He says: "We don't want to geotag all of it, just the significant proportion that is about a place or specific to a place, for example a pizza parlour or a local news item."

If the industry keeps geotagging simple and also makes it local, he adds: "There are several ways to derive location information. First, a structured address - for example where a location is, such as a store or restaurant."

However, he adds a cautionary note: "This is geocoding plain and simple, but doesn't necessarily disseminate location information to the relevant audience, or content that is not address-based." Profitable geocoding would have to take account of those matters.

Look who's geotagging now

It wouldn't be surprising if a new geotagging app is announced between the time of writing and the time you read this. The recent growth of geotagging doesn't plot as a rising straight line, it's more of a sharp upwards curve.

Little more than a year ago Geotate, a UK-based spin-off of Philips Research, was announcing a quick and efficient solution for geotagging photos. Called Capture and Process, it involved fitting a device to a digital camera to collect a small packet of information from GPS satellites. This information would then be processed and added to photos automatically by computer-based software when images were downloaded from the camera.

Geotate was subsequently taken over by Road Holding Group, but that's by the way.

Now, of course, smartphones with their GPs, cameras and suitable apps can do it even more easily. The image quality may not match that of a high-end digital camera, but it doesn't have to. Geotagging generally is not about pixel-by-pixel clarity, it's about showing a place, telling where it is and quickly describing what it's about.

Among the current leaders in geotagging, several have been featured on TheWhereBusiness in the last year or less:

The Pixelpipe app allows users to attach geolocation information to status updates which can be posted to more than 30 services, especially social networks.

GyPSii, which is available across WeFiApps (a Wi-Fi powered launch pad for data-intensive mobile applications) enables users to geotag their location with related images, comments, status updates and other information.

Flickr for iPhone and Blackberry smartphones lets users take photos on their phones, geotag them, title them, re-size them and upload them to the Flickr website for sharing with friends.

locrExplorer for iPhone and iPod Touch makes it possible to explore and share geo-related photos and location-based content within the locr geotagging community.

Locr and Skyhook Wireless further announced a partnership to bring Wi-Fi positioning to locr's geo-tagging community. It was said this would improve the accuracy and availability of location information for a significant number of existing locr users.

But where's the working model?

The game has grown bigger lately with the big social networks introducing some form of geotagging. There are also third-party apps that can add location and geotagging to Facebook and Twitter.

Geotagging may proliferate but it still has to make money. TheWhereBusiness's editor, Thomas Hallauer, offered one possibility for monetisation when he was discussing Abaq.us and other geotagging services.

"The operator could be paying for the app and act as service provider, but most likely it will run as a service deployed by the operator with a revenue share model," he said. "The customers would be charged minimally to geotag photos, post their location tracks, share location data on personal hubs and feed it into their chosen social network.