Calibration of iPad4


#1

The Calibrator app download says it is incompatible with iPad4, and the camera intrinsics are not exposed in the SDK, so how can a sensor on an iPad4 be calibrated ?


#2

@phila,

A fix has been submitted to the App Store, the updated version should be available soon.

-Jim


#3

Thanks, it’s available now! Calibrating happily.


#4

Unfortunately, Version 2.2 crashes in the calibration (outdoor mode) when it gets to the ‘refine’ dialog, and in the indoor mode, refine shows a black screen, so the refinement cannot be performed. The real problem seems to be FOV mismatch between the sensor and the ipad camera, and the calibration does not seem to have improved this, in fact, it may be worse now than with an uncalibrated sensor. The calibrator appears to bypass lens calibration if not using a wide lens, is this intentional ?
(or perhaps the FOV mismatch is between the scene camera and the ipad camera, as I am using the StructureAR demo simple scene to gauge the results of the calibration, and there seems to be a significant FOV mismatch there, I’ll try adding an FOV adjustment to the scene and see if I can improve the reult.)


#5

Make sure you’re calibrating for the standard lens. Others on here had that issue.

-Jim


#6

Yes, I was using the standard lens calibration, and it seemed to skip the lens calibration step and move immediately to bracket calibration.

I did incorrectly select the wide angle calibration option the first time, and got as far as the second checkerboard step before realizing i had selected wide lens option. the dialog to switch to standard lens calibration would not dismiss, so i restarted the app.

Since the app crashed using the outdoor calibration, i succeeded in indoor calibration up to the point of refinement, but the black screen kept me from performing that step.

Now, whenever I launch the calibrator app, even after rebooting my ipad and re-installing the calibrator app, the app crashes on launch right after showing the screen where i could select “RECALIBRATE”.


#7

@phila,

Thanks for reporting the issue, we will try and reproduce it in house.

-Jim


#8

Any news on this? I have the same problem: crashes as the “refine” dialog starts coming up.


#9

FWIW, the release of Nov 28 fixed this for me.


#10

@martin.gregory Great to hear! Indeed, we were able to track this problem down and address it, and just didn’t get a chance to update the forum here. For the curious, the problem was related to the armv7 architecture on the iPad 4. We definitely recommend upgrading when you can to the new arm64 devices, since they are now much faster. We’ll do our best to maintain iPad 4 support a little longer.


#11

Yes, the latest release has fixed this for me, as well. Thanks for the support!