With that device rotation matrix you can only rotate your objects around the screen, where the rotation center point is the center of the device. This is independent of GPS location coordinates, and as the name of that matrix suggests, it is really rotation only, not translation (moving around the objects on any axis).
But to answer your question: yes, it is possible to just use the sensor data without GPS and have 3D objects move around on the screen. And it will work well for most use cases, like augmented reality games where you usually sit as a player and move the camera around. If you need to change the positioning of the 3D objects according to the current device location and movement, it gets a bit more complicated. You could make use of the GPS coordinates for translation but it wouldn't be real time suitable, because GPS alone is usually not precise enough. You need to combine several sensors (including the camera) for making an augmented reality app possible that gives a seamless experience and allows the user to freely walk around. You could make use of acceleration sensor data for getting an idea of the current device / user movement direction. With that information you could predict a translation until the next GPS location update gives you certainty about the current location. You also could make use of realtime image analysis for calculating the current movement direction based on changes in the video preview frames. On Thursday, July 5, 2012 1:11:20 PM UTC-5, santy wrote: > > Thank you very much Nobu. And is it possible to place the 3D object just > to see the object with the camera on its position without using the GPS??? > > > El jueves, 5 de julio de 2012 20:02:03 UTC+2, Nobu Games escribió: >> >> On Thu, Jul 5, 2012 at 12:47 PM, santy wrote: >> >>> Yes, of course I have been trying with all the frameworks I have found >>> (LooakAR, min3D...) and I am sure I can do what I need with them but I >>> don´t know how. I wrote here in order to find someone who has done exactly >>> the same I have to do (there must be a lot) and to know how they did it (I >>> need a tutorial that explains it or some advices). >>> >>> Thanks >>> >>> >>> El jueves, 5 de julio de 2012 19:40:21 UTC+2, Nobu Games escribió: >>>> https://www.google.com/search?q=Android+Augmented+Reality >>> >>> >> You need to make use of SensorManager and register a SensorListener in >> order to construct a device rotation matrix. Luckily Android already >> provides a method that calculates that matrix which is ready for use in >> OpenGL: >> >> SensorManager.getRotationMatrix()<http://developer.android.com/reference/android/hardware/SensorManager.html#getRotationMatrix%28float[],%20float[],%20float[],%20float[]%29> >> . >> >> *This matrix is ready to be used by OpenGL ES's glLoadMatrixf(float[], >>> int)<http://developer.android.com/reference/javax/microedition/khronos/opengles/GL10.html#glLoadMatrixf%28float[],%20int%29>. >>> >>> * >>> >>> * Note that because OpenGL matrices are column-major matrices you must >>> transpose the matrix before using it. However, since the matrix is a >>> rotation matrix, its transpose is also its inverse, conveniently, it is >>> often the inverse of the rotation that is needed for rendering; it can >>> therefore be used with OpenGL ES directly. * >>> >> You also may want to implement an algorithm that reduces the noise from >> the sensor data, otherwise the 3D objects will jitter on the screen. The >> simplest approach is calculating a median and / or weighted average over >> time. >> > -- You received this message because you are subscribed to the Google Groups "Android Developers" group. To post to this group, send email to [email protected] To unsubscribe from this group, send email to [email protected] For more options, visit this group at http://groups.google.com/group/android-developers?hl=en
