What I would say to Nokia about mobile AR (if it would listen)
I have been struck off the list of the Nokia Augmented Reality co-creation session, so here is a gist of what I was intending to say about AR-friendly mobile devices.
I will not repeat obvious here (requirements for CPU, FPU, RAM etc.) but concentrate on things which are often missed.
I. Hardware side
1. Battery life is the most important thing here. AR applications are eating battery extremely fast – full CPU load, memory access, working camera and on top of it wireless data access, GPS and e-compass.
It’s not realistic to expect dramatic improvement in the battery life in near future, though fuel cells and air-fueled batteries give some hope. If one think short term the dual battery is the most realistic solution. AR-capable devices tend to be quite heavy and not quite slim anyway, so second battery will not make dramatic difference (iPhone could be exception here).
Now how to make maximum out of it? Make batteries hot-swappable with separate slots and provide separate battery charger. If user indoor he/she can remove empty battery and put it on charge while device is running on the second.
2. Heating. Up until now no one was paying attention to the heating of mobile devices, mostly because CPU-heavy apps are very few now (may be only 3d games). AR application produce even more heat than 3d game and device could become quite hot. So heatsinks and heatpumps are on the agenda.
3. Camera. For AR the speed of the camera is more important than the resolution. Speed is the most important factor, slow camera produce blurred images which are extremely hard to process (extract features, edges etc)
Position of the camera. Most of the users are holding device horizontally while using AR. Specific of the mobile AR is that simultaneously user is getting input from the peripheral vision. To produce picture consistent with peripheral vision camera should be in the center of the device, not on the extreme edge like in N900.
Lack of skewing, off-center, radial and rolling shutter distortions of the camera is another factor. In this respect Nokia phone cameras are quite good for now, unlike iPhone.
4. Buttons. Touchscreen is not very helpful to AR, all screen real estate should be dedicated to the environment representation. While it’s quite possible to make completely gesture-driven AR interface buttons are still helpful. There should be at least one easily accessible button on the front panel. N95 with slider out to the right is the almost perfect setup – one big button on front panel and some on the slider on the opposite side. N900 with buttons only on the slider, slider sliding only down and no buttons on the front panel is the example of unhelpful buttons placement.
II. Software side
Platform fragmentation is the bane of mobile developers. Especially if several new models launched every quarter. One of the reasons of the phenomenal success of iPhone application platform is that there is no fragmentation whatsoever. Whit the huge zoo of models it practically impossible support all that are in the suitable hardware range. That is especially difficult with AR apps, which are closely coupled with camera technical specification, display size and ratio etc. If manufacturers want to make it easy for devs they should concentrate on one AR-friendly line of devices, with binary, or at least source code compatibility between models.
2. Easy access to DSP in API. It would effectively give developer a second CPU.
3. Access to raw data from camera. Why row data from camera are not accessible from ordinary API and only available to selected elite developer houses is a mistery to me. Right now, for example for Symbain OS camera viewfinder convert data to YUV422, from YUV422 to BMP and ordinary viewfinder API have access to BMP only. Quite overhead.
4. API to access internal camera parameters – focus distance etc. Otherwise every device have to be calibrated by developer.
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