MISR in-flight geometric calibration

Date of this revision: 25 July 2001

This page discusses aspects of the geometric calibration of the MISR instrument, and is designed for users of MISR science data who need to know the mathematical details of the calibration.

Contents:

• Geometric calibration results
• Where to go next

Geometric calibration results

This section provides a summary of the results obtained during in-flight geometric calibrations since the launch of MISR on December 18, 1999, aboard NASA's Terra spacecraft on.  It includes:

1. Identification of each update version for the MISR camera geometric model (CGM), and the affected parameters within the CGM
2. Estimates of geolocation accuracies related to the respective updates of the MISR CGM.

There are five versions of the CGM that have been used operationally since the launch of MISR, as follows.

F01_02 - initial at-launch version

This version was calibrated on the ground only. It has a problem with orientation of the spectral bands for nadir and aft-pointing cameras. This calibration was used only for a few days following the start of image data acquisition.

F01_03 - band orientation problem fixed -- delivery date: 28-Feb-2000

Band to band coregistration within each camera is better than 50 m. Large coregistration errors ranging from 2500 m between the nadir and B cameras, to 6000 m between the nadir and D cameras. Geolocation of the nadir camera is within 400 m.

F01_04 - limited calibration to support press conference data preparation -- delivery date: 30-Mar-/2000

This has somewhat improved coregistration. The coregistration errors range from 1000 m between the nadir and B cameras, to about 3000 m between the nadir and D cameras. Geolocation of the nadir camera did not improve.

F01_05 - first full calibration using ground control points data sets. Delivery date: 08/14/2000

There are significant changes in certain of the CGM parameters compared to the previous version. See Table 1.

Table 1: Correction to the CGM parameters, Version F01_05

In this calibration, the geolocation errors are  significantly improved. Table 2 gives the estimate of geolocation errors for data processed using CGM Version F01_05 during the period May - June of 2000. The results show somewhat worse geolocation performances of the D-aft camera when compared with the performances of the other 8 cameras. This version of the CGM should be used to process data corresponding to the orbit range 995 - 2718.

Table 2: Estimate of geolocation errors, CGM Version F01_05  

F01_06 - update based on the calibration of DA camera only. Delivery date: 08/25/2000

Only parameters of the D-aft camera were changed from the previous version. See Table 3.

 Table 3: Correction to CGM parameters, Version F01-06

Table 4 gives the estimate of geolocation errors for data processed with the CGM Version F01_06 during the period September - December 2000. Recent studies conclude that geolocation performance of CGM version F01_06 are stable. That is, more recent assessments show no significant change since December 2000, and are very similar to the estimates in Table 4, with variations of geolocation accuracy being seen only in the D-aft camera, with a magnitude of about +/- 350 m.

Table 4: Estimate of geolocation errors, CGM Version F01_06

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