I have an iphone 7 and I'd like to develop an augmented reality application for it. Anyway I can't find a way to get the rear camera intrinsic parameters fx, fy, cx, cy.
Is there a way to get these parameters for my device if they're not documented?
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I'm working on an AR project (Unity) and I want to use an external camera instead of my Android's original one. I saw that Vuforia has such a feature - but claims that ny using that, Ground Plane detection wouldn't work at all and ModelTargets performances taking a hit.
I also saw EasyAR has CustomCamera and Camera2 lib in ARCore.
Question is: What's the best way to approach this? has anyone experienced using an external camera? and with what AR solution? (ARFoundation / Vuforia / EasyAR...).
2nd Question: What should I look for when buying said UVC? Any examples for one?
Also I'd like to hear about experiences with AR solutions regardless of the external camera thing.
Thanks in advance!
Unfortunately, this is unlikely to work with an external camera.
A key part of AR is having a precise calibration of the camera's optics. Without that, it's not possible to accurately analyze the world to draw new objects in it or other AR effects.
A UVC webcam doesn't come with any such calibration information. So it would have to be calibrated somehow, and the calibration information given to Unity's AR engine. I don't know if that's possible with Unity in some way.
Note that not that all internal camera devices on Android are calibrated enough for AR either, but the ARCore team is certifying devices that have sufficient calibration in place.
I know by combining accelerometer and gyroscope, we can access the gravity and device motion separately. But I need to know how does Xcode calculate it when I simply using devicemotion.gravity. Any algorithm available?
So I'm building this application to see how many rounds somebody cycled. I don't want to do this using the GPS, but with the other sensors of the iPhone 4+ (Accelerometer, Gyroscope and Compass). I want to detect if the phone has rotated 360 degrees, but the phone is almost never facing upwards, like a compass. What is the best way to achieve this?
On Android there is a method to compensate the phone's tilt on the compass with the accelerometer data. I think it was
static boolean getRotationMatrix(float[] R, float[] I, float[] gravity, float[] geomagnetic)
http://developer.android.com/reference/android/hardware/SensorManager.html
I'm trying to detect a swinging motion with an iPhone 4 using the gyro/accelerometer. I searched for some posts on SO about this, but couldn't find anything specific to my issues.
Do I need to do any sort of calibration for data from the gyroscope/accelerometer?
Anyone think of how I would measure a swinging motion?
Thanks!
1: Most iPhone games using the accelerometer don't do any calibration, but not all iphones are the same; there is some variation in accelerometer calibration. You could add a manual or automatic calibration to your program. If however, detecting a swinging motion is all you want, calibration is not necessary.
2: Apple has a nice little app that generates graphs of accelerometer motions in the iPhone SDK. You can download and build that and see the measurements for the motion you want. Then you can write code to detect similar accelerometer measurements.
Is there a way to detect if an iphone lying down in a table face up is rotating?. I do realize that this kind of movement is not reported by the accelerometer and neither is it reported to the - (BOOL)shouldAutorotateToInterfaceOrientation:(UIInterfaceOrientation)interfaceOrientation method.
Is there a way to detect angle variations for the phone rotating this way?. Thank you.
The gravity vector will be constant as it rotates on a flat table so you won't see anything on the accelerometers. You could follow compass heading changes to detect this rotation but only on an iPhone 3G S. See the CLLocationManager for details, look at the heading methods.
EDIT - With an iPhone 4 you can detect the rotation using the gyros. There is a new class in iOS 4 called CMMotionManager for getting rotation rate from the gyros.
When the phone is stationary the sum of the acceleration vectors should be +1. When the phone is rotating (assuming the sensor is off-center) the sum of the vectors should be more than 1 and (hopefully) somewhat constant.
If you look at the decay of that curve, I wouldn't be surprised if that shape is distinctive enough to be used to determine whether the phone is rotating or not.
This is the AccelerometerGraph sample app from Apple.
I guess you could do it if the iPhone has a compass. Other than that I don't think it will be possible or reliable.
This would really depend on the location of the accelerometer on the device, i just tested this using the accelerometergraph sample application on a 2g itouch and you can see the initial acceleration on the x and y axis(the 2g does not have the accelerometer in the center of the device I guess). So in a sense you could detect the rotation, however I think the challenge would be differentiating that acceleration from directional acceleration. And I'm sure the values would change if apple placed the accelerometer in different locations on different models. There would definitally not be any way of doing it via shouldAutorotateToInterfaceOrientation, I recommend you load the accelerometergraph sample application in the sdk and experiment with the acceleration vectors to see if you can isolate a rotation vector reliably on multiple devices.