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Phantom4RTK's Camera, sensor size

Hello

Phantom 4 RTK 's Camera ‘FC6310R_8.8_5472x3468’ is default.
I think sensor size is a little wrong.

Sensor Width 12.8333 / Sensor Height 8.55554 / Pixel Size 2.34527

Sensor Width 13.2 / Sensor Height 8.8 / Pixel Size 2.41228

Phantom 4 RTK has unique internal camera parameter, so, I change every time several parameter. So it is not so critical issue.
But beginner user say ‘Why Pix4D provide incorrect value? which is true ?’

I know why Pix4D provide such sensor size ? (ex. Official information from DJI )

Best Regards.
Seiichi Takayama

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Hi,

As you already pointed out, the initial values from the manufacturer (EXIF) and the ones in the Pix4Dmapper internal camera database are not identical.

It is a general practice that we refine/calibrate the parameters in order to take into account some systematic errors that would happen when using only the EXIF parameters. Since the EXIF only contains approximate parameters the camera optimization would typically drift toward other parameters (similar for all P4RTK cameras) when using them for processing.

Every camera is different and the parameters can slightly vary and therefore also the parameters in the Pix4Dmapper internal camera database are approximate in the end. Cameras are sensitive to vibration, temperature, etc., and the software will, by default, optimize the internal parameters for each project starting from the initial parameters from the database.

However, we are happy to hear that your customized camera model with the EXIF values worked. As long as you are savvy enough to calibrate your own camera model with the desired values, I don’t see why you should not apply this method.

Cheers,
Nikoleta

Dear Nikoleta

Thank you your reply.
And sorry to late my response.

I see it is very different and complex issue.
My camera model is not incorrect , and , default camera model is not incorrect, too.

One more question.
Sensor size is not calibrated, right ?
Calibrated parameter is only below. (Quality report’s “internal Camera Parameters”)
Focal length, Principal Point x/y , R1, R2, R3, T1, T2

Best regards.
Seiichi Takayama

Hi Seiichi,

As you mentioned both the camera model from Pix4Dmapper`s database and the customized camera model might have correct results because in the end the values of the parameters are just slightly different.
What Pix4Dmapper does during processing of Step 1. is to optimize the values you mentioned:
Focal length, Principal Point x/y , R1, R2, R3, T1, T2, without changing the Sensor size.

I hope I answered your question.

Best regards,
Nikoleta.

Dear Nikoleta

Step 1. is to optimize the values you mentioned

Thank you! I see.
And this issue share Japanese office’s staff.
Please hear detail from them.

Best regards.
Seiichi Takayama

Hi @seiichi_takayama,

We will contact you via email for further details.

Have a nice day.

Best,
Nikoleta

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