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Author Topic: Exporting camera calibration to Inpho  (Read 276 times)

GGR

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Exporting camera calibration to Inpho
« on: September 22, 2021, 12:35:30 PM »
Hey there,

While I was controling an export of a camera calibration in Inpho format made on a 1.7.4 release, I noticed significants differences between the floatings displayed on the camera calibration tool (which are the same as stored in an Agisoft xml export) and the values stored on the Inpho txt file.

The following values are the adjusted ones of a CityMapper. The distortionlessness of this sensor is traducted by the lack of k1,k2,etc and p1 and p2 values.
Code: [Select]
<?xml version="1.0" encoding="UTF-8"?>
<calibration>
  <projection>frame</projection>
  <width>10336</width>
  <height>7788</height>
  <f>15963.115384616023</f>
  <cx>-1.3333000000002044</cx>
  <cy>-4.7148000000001868</cy>
  <date>2021-09-22T08:40:25Z</date>
</calibration>

The table below is the export of the same calibration (adjusted) in Inpho.
Code: [Select]
$CAMERA
  $TYPE : unknown
  $DATE : 10:43:20 22/09/2021
  $BRAND : Custom
  $KIND : CCDFrame
  $CCD_INTERIOR_ORIENTATION :
     299.114       -0    5166.17
       0.0000000000    -299.114    3888.79
  $CCD_COLUMNS : 10336
  $CCD_ROWS : 7788
  $PIXEL_REFERENCE : CenterTopLeft
  $FOCAL_LENGTH :    53.3681
  $PRINCIPAL_POINT_PPA :     0.000000     0.000000
  $DISTORTION_TYPE :  Polynomial
  $RADIAL_COEFFS :
                      0             -7.25205e-19                  6.26401e-22                  7.52744e-24
                      -1.34583e-26                  0                  0                  0
  $DECENTRE_COEFFS :
                      3.46799e-19                  1.68792e-19                  0                  0
  $GPS_ANTENNA_OFFSET :     0.000000     0.000000     0.000000
  $CAMERA_MOUNT_ROTATION :     0.000000

As you can notice, principals points coordinates ($PRINCIPAL_POINT_PPA) are set to 0 and radials ($RADIAL_COEFFS) as well as tangentiels ($DECENTRE_COEFFS) distortions are not set to 0.
Actually, I was expecting the exact opposite result.

Is this way of converting values is the regular one ? Along my research on this topic I noticed ways to convert values but the difference here seems to be too significant.

Best regards
Gabriel
Best regards
Gabriel