Camera calibration for fx and fy


I am using NV camera calibration tools to generate rig.json.

The camera is Sekonix SF3325.

Only Cx and Cy are shown. How can I calculate fx and fy?

The rig.json is listed as follows:

"rig": {
    "sensors": [
            "correction_rig_T": [
            "correction_sensor_R_FLU": {
                "roll-pitch-yaw": [
            "name": "FC_60",
            "nominalSensor2Rig_FLU": {
                "roll-pitch-yaw": [
                "t": [
            "parameter": "",
            "properties": {
                "Model": "ftheta",
                "bw-poly": "0.000000000000000 5.45554212294519e-4 3.40270633891748e-9 -1.85083719184131e-11 1.44576818100978e-14 ",
                "cx": "1021.738831",
                "cy": "468.087280",
                "height": "1208",
                "width": "1920"
            "protocol": "camera.virtual"

Dear songwen.huang,

Could you please let us know your calibration step in detail?
I think the json file is for instrinsic.
Could you please refer to DRiveWorks calibration tutorial? Thanks.

Hi SteveNV,

We follows the steps in the manual to calibrate the camera.

Then, the above rig.json is generated after the calibration process.

Please let me know if there is any way to calculate fx and fy from the rig.json file.


Dear songwen.huang,

According to the json file, you are using f-theta model. Ftheta doesn’t have fx/fy parameters. Thanks.

Hi SteveNV,

How to calculate fx and fy in ftheta model?

Dear songwen.huang,

Ftheta in NV internal model and similar to “A generic camera model and calibration method for conventional, wide-angle, and fish-eye lenses.” IEEE transactions on pattern analysis and machine intelligence 28.8 (2006): 1335-1340.

Please help to check it for your understanding. Thanks.