Editing Digital compass
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- | All information pertains to the | + | All information pertains to the N900. |
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+ | = Why a compass is needed = | ||
+ | == Augmented Reality (AR) == | ||
* GPS gives location of device; compass gives orientation | * GPS gives location of device; compass gives orientation | ||
* Allows pointing the device and getting information relevant to the pointed direction | * Allows pointing the device and getting information relevant to the pointed direction | ||
* E.g. Layar, Wikitude | * E.g. Layar, Wikitude | ||
- | + | == Navigation == | |
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* Car navigation | * Car navigation | ||
* On-foot navigation | * On-foot navigation | ||
** Map rotation | ** Map rotation | ||
- | + | = Connection options = | |
* Optical (use one of the cameras, plus image processing) | * Optical (use one of the cameras, plus image processing) | ||
** Best to use user-facing camera, so the world-facing can be used for capturing the world image for AR | ** Best to use user-facing camera, so the world-facing can be used for capturing the world image for AR | ||
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* USB | * USB | ||
** Unknown if USB host possible. | ** Unknown if USB host possible. | ||
** Unknown if power is available from USB. | ** Unknown if power is available from USB. | ||
- | * | + | * IRDA |
** Is unsupported at this point. The device only has an CIR transmitter. | ** Is unsupported at this point. The device only has an CIR transmitter. | ||
* Bluetooth | * Bluetooth | ||
** Bluetooth data | ** Bluetooth data | ||
** Bluetooth audio - sending analog signals via Bluetooth microphone for digital signal processing on the N900 | ** Bluetooth audio - sending analog signals via Bluetooth microphone for digital signal processing on the N900 | ||
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* FM radio | * FM radio | ||
** Requires headphones be connected | ** Requires headphones be connected | ||
** Signal processing of audio in software | ** Signal processing of audio in software | ||
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+ | = Compass chips or sensors = | ||
* Honeywell HMC5843 | * Honeywell HMC5843 | ||
** I2C interface | ** I2C interface | ||
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* Dinsmore analog | * Dinsmore analog | ||
- | + | = Ready-built compass modules = | |
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* Ocean Server OS4000 | * Ocean Server OS4000 | ||
* Ocean Server OS5000 | * Ocean Server OS5000 | ||
** USB and RS232 interface | ** USB and RS232 interface | ||
- | + | = Microcontrollers = | |
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+ | = Converters = | ||
* I2C to RS232 | * I2C to RS232 | ||
** http://www.gedanken.demon.co.uk/rs232-converters/i2c.html | ** http://www.gedanken.demon.co.uk/rs232-converters/i2c.html | ||
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** http://www.emv-electronics.com/de/intro/i2cbusadapter.htm (seems unavailable for purchase) | ** http://www.emv-electronics.com/de/intro/i2cbusadapter.htm (seems unavailable for purchase) | ||
- | + | = Designs = | |
- | + | == Optical image processing of compass == | |
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* Periscope-like mirror | * Periscope-like mirror | ||
+ | == Ready-made RS232 compass modules with RS232-Bluetooth conversion == | ||
+ | == Custom board designs == | ||
- | + | = Alternatives to a digital compass = | |
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* Use GPS motion to determine direction | * Use GPS motion to determine direction | ||
** Only useful for navigation, not AR | ** Only useful for navigation, not AR | ||
** Does not work if standing still | ** Does not work if standing still | ||
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* Use image processing for AR | * Use image processing for AR | ||
** E.g. artoolkit | ** E.g. artoolkit | ||
** Still you cannot get absolute orientation of device | ** Still you cannot get absolute orientation of device | ||
- | * Initialized orientation + delta orientations | + | * Initialized orientation + delta orientations |
** Maybe you can initialize the device to a known orientation (e.g. straight north), then use optical flow and/or accelerometer data to extrapolate subsequent orientations | ** Maybe you can initialize the device to a known orientation (e.g. straight north), then use optical flow and/or accelerometer data to extrapolate subsequent orientations | ||
* Optical compass + manually dragging an on-screen compass to match | * Optical compass + manually dragging an on-screen compass to match | ||
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** But for navigation or rotating maps, it could work: just glance at the optical compass, then drag the map icon to match the orientation. | ** But for navigation or rotating maps, it could work: just glance at the optical compass, then drag the map icon to match the orientation. | ||
* Combined GPS/optical compass for daytime use: | * Combined GPS/optical compass for daytime use: | ||
- | ** Use GPS location and time info to calculate current sun location | + | ** Use GPS location and time info to calculate current sun location |
** Let user optically align to visible sun | ** Let user optically align to visible sun | ||
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