Is it possible to play lumion scenes within a webbrowser.
CRhoades has more directly answered, so just a few thoughts as I see things.
Well, yes it is, but not the way you are considering as realtime. Exporting images and video in a common format allows any user to 'play' a scene on any platform/browser, its just that the scene is predetermined by the vizualiser using Lumion as to what they want the 'end-user' to see. Chances are that may be fine for 95% of web visitor type users.
The ability to provide real-time arch viz is not a small matter. The real key is not the technology, but the end-user, their platforms (generally read that as lack of suitable hardware), and their actual bahaviour mode to actually 'explore' scenes.
It's also a time thing, how many people are going to spend potentially much longer in a real-time app exploring the arch viz as compared to being (well) directed about the salient points of the property? That is, if someone is viewing on the web, its more likely they are in there for a 5 minute quick look, give me the overview. Getting them to change behaviour from passive to active explorer has just (so far) not proven to be the case. Perhaps as time goes by that may change.
Certainly there are plenty of good reasons to provide real-time, but in this time-limited world, if you ask someone to spend 15 minutes exploring as compared to 5 minutes viewing well structured presentation video of the same arch viz, then I would guess most would opt for the video.
Perhaps as an additional service those that want to then go into more detail (perhaps offline) via exploring could then be given the chioce to select an interactive real-time view. But in doing so, that means the provider of the arch viz then needs to spend time producing 2 things for the same communication, ie can be cost exclusive to the process. Sort of like producing 5 different types of drawings and renderings of the same face of the building just to impart slightly different look and feel about it, nice but who has the time.
As a real-time developer myself I would love to see such things possible, and it will happen as all the technology progresses, but many have tried over the last 10-15 years. Web enabled has not proven successful, distributing something (a scene file to play) over the web can be, so in lots of cases its been used more for direct presentation, one-to-one and specialised provision to clients/end-users.
I'm not saying that its not possible, or some form is not possible in future. One way things might go is to base content that uses the new Flash API as the rendering level platform, thus making it widely available and web enabled. UnReal have just recently demo'd their engine running a real-time game in Flash, and Unity are in process of porting as well I gather, so its potentially possible, just not anytime soon.
Another technology some are trying to use is server rendered and streamed images that look like interactive real-time to the end-user, but that requires lots of servers, clouds, and most importantly users with extreme high bandwidth at their doorstep, fine in some parts of the world but not the majority.