Clementine Near-Infrared Global Multispectral Lunar Map

Updated 2007-07-30

We are pleased to announce the availability of a full-resolution version of the Clementine near-infrared (NIR) lunar mosaic. Processed to 100 m/pixel spatial resolution, a PDS-compliant image cube version (with detached ISIS labels) of this 6-band (1100 to 2780 nm) multispectral mosaic can be viewed or downloaded via FTP from the PDS Imaging Node's pdsimage2.wr.usgs.gov FTP site. This Preliminary Release (V. 0.1) of the full-resolution mosaic marks the beginning of the review process by PDS peer reviewers. Users of these data should keep in mind that this version remains subject to revision pending the outcome of this review process.

These full-resolution data are compatible with the previous PDS Clementine UVVIS 'Full Resolution Digital Image Model' available through Map-a-Planet and the PDS Planetary Image Atlas. Once finalized, these multispectral data will also be available through these Web sites.

Note that the NIR polar data (latitudes greater than 70 degrees) are now available. See documentation on the FTP site for more details.

Final Note: Paul Lucey (HIGP/Univ. Hawaii), original calibration scientist for the Clementine NIR data, has derived an additional set of wavelength-dependent empirical correction factors. These are described in this presentation (Portable Document Format, PDF format, 778 KB), alternatively available in Microsoft PowerPoint format (PPT, 2.6 MB). Use them at your own risk, and please be aware that these appear to be most accurate at the lunar mid-latitudes.

Figure 2: Clementine NIR mosaics at 1100 nm with empirical orbit-to-orbit corrections applied, 500 m/pixel

1092 x 849, 315 KB (a) Western lunar hemisphere (70° N to 70° S, 180° to 360° E). Note that variations between orbits and camera modes visible in Figure 1 have been substantially removed.

1092 x 849, 330 KB (b) Eastern lunar hemisphere (70° N to 70° S, 0 to 180° E).

Figure 3: Clementine NIR mosaic of Aristarchus Plateau at 1100 nm (centered at 25° N, 310° E)

1092 x 970, 180 KB (a) radiometrically corrected

1092 x 970, 180 KB (b) after empirical frame-offset corrections

Figure 4: Clementine NIR mosaic of South Pole-Aitken basin at 1100 nm (centered at 45° S, 195° E)

1061 x 758, 330 KB (a) radiometrically corrected

1061 x 758, 320 KB (b) after empirical frame-offset corrections

Figure 5: Ratio (1500 nm/ 2000 nm) of Clementine NIR mosaic of the western hemisphere of the Moon (70° N to 70° S, 180° to 360° East)

1092 x 849, 380 KB (a) radiometrically corrected

1092 x 849, 390 KB (b) after empirical frame-offset corrections

Figure 6: Ratio (1500 nm/ 2000 nm) of Clementine NIR mosaic of the Aristarchus Plateau region (centered at 25° N, 310° E)

1092 x 970, 445 KB (a) radiometrically corrected

1092 x 970, 450 KB (b) after empirical frame-offset corrections

Frame Offset Corrections

After radiometric and photometric calibrations were applied to the NIR data (e.g., Eliason et al., 2003), additional corrections were derived to adjust for remaining problems in the characterization of specific camera modes and the drift of radiometric properties over the two month Clementine observation period. Problems in the existing NIR calibrations (standard processing version) were apparent in both NIR albedo images and ratio images of NIR and NIR to UVVIS bands. Though such problem areas were typically associated with 10° latitude strips where specific camera settings were poorly characterized, no systematic correction for these residual errors was apparent based on comparisons of image means with gain and offset camera mode values. As a result, a set of empirical corrections was developed to reduce within- and between-orbit variations for each NIR band as described below.

To identify Clementine NIR frames with residual calibration errors, ratio images were created by dividing each radiometrically and photometrically calibrated NIR band to the USGS calibrated 750 nm UVVIS data. To make computational processing more efficient, the NIR data were divided by longitude into twelve 30° wide strips at a resolution of 1 km/pixel. Several thousand "truth" image frames were then selected for each NIR band of each strip based on orbits and camera mode states that demonstrated the least amount of radiometric variability across NIR/UVVIS ratio images. Image frames that were not included in the selected truth sets were then adjusted by computing an offset for each frame based on color ratio differences in overlapping regions of the frame being corrected and the surrounding truth-set frames (frame offset = derived ratio offset * 750 nm albedo). This procedure was applied to each longitude strip to derive a global set of offset frame corrections for each NIR band.

Derived frame offset corrections for each NIR band were then applied to a global mosaic of Clementine NIR data at 2 km/pixel resolution. New ratio images of the NIR channels over the UVVIS 750 nm data were created from the frame offset-corrected NIR data to evaluate results. Uniformity across camera mode settings and orbits was improved in the resulting ratio images for most regions. Offset correction values for NIR frames that were identified as unimproved by the automated offset correction algorithm due to within-image gradients or lack of adequate surrounding truth images were either eliminated from the offset corrections or adjusted manually based on visually matching values with surrounding frames in the ratio images.

After applying the best set of frame offset corrections derived through the above steps, a final small offset correction was then computed for every image frame in the Clementine global mosaic to correct for residual between-orbit variations. This was carried out by differencing the global ratio of each NIR band over the 750 nm band by the same data after applying a longitudinal median filter. The width of the longitudinal median filter was varied until a filter was identified that captured color offsets across orbits while minimizing the influence of geologic albedo and color boundaries on the subsequently derived offset corrections. A frame specific offset for all six NIR bands was derived from the mean difference of the pre- and post-filter ratio images over each frame's coverage (frame offset = filter specific constant * ratio offset * 750 nm albedo). Derived frame offsets were then smoothed as a function of latitude within each orbit and added to the previous offset correction values.

The final result of the offset deviation processing described above was a single text file (nir_mosaic_frameoffset.txt) [4.2 MB, text] containing offset corrections by NIR band for every image frame in the Clementine 2 km mosaic. A backplane containing the area of each Clementine frame is included in the ISIS cube files of each 0.5 km/pixel NIR mosaic. These offsets values were then subtracted from the radiometrically corrected NIR data to create the offset-corrected 0.5 km/pixel mosaics.

A final multiplicative correction equivalent to the month1-to-month2 correction applied to the calibrated global UVVIS data was also applied to the offset corrected NIR mosaic (frame based NIR calibrations were made relative to the 750 nm UVVIS data before this final multiplicative correction had been applied). Orbit-to-orbit multiplicative corrections as a function of Clementine frame number (included as the backplane on the 500m Isis cubes) are included here (nir_mosaic_framemult.txt) [3.9 MB, text].

Apollo 16 Normalization

Apollo 16 soil measurements previously used to calibrate the UVVIS data (Pieters et al., 1999 [1.5 MB, PDF ];) were convolved through the first four NIR filter transmission curves. The longest NIR wavelengths (2600 and 2780 nm bands) were not normalized to these soil measurements because reflectance information was not available and may be complicated by the presence of thermal emission signatures. The values obtained from the soil spectra were then compared with the same Apollo 16 landing site location used to calibrate the UVVIS data to obtain a reflectance normalization coefficient for the first four bands of the NIR data (1100 - 2000 nm). Multiplicative correction factors derived from the standard processing data and the offset corrected NIR data were consistent to ~ 2% or better for all four bands. Due to a decrease in orbit to orbit variability around the Apollo 16 landing site, values derived from the final offset corrected mosaics were used for the normalizations of both datasets and are presented in Table 1 below.

Table 1: Apollo 16 Calibration Coefficients

NIR band	Coefficient
1100 nm	0.1279
1250 nm	0.1167
1500 nm	0.1587
2000 nm	0.2953

Top

---

Notes on Usage

This First Release of the Clementine NIR mosaic represents a significant improvement in radiometric calibrations over the original mission calibrations generated by Hye Sook Park (Lawerence Livermore Laboratory) from preflight calibration of the instrument. Assessement of the inflight image showed calibrations gain and offset states with up to 10% residual errors in addition to the camera suffering from a drifting additive offset which differs throughout an orbit and from orbit to orbit (Lucey et al., 1997). In spite of the improvements over the original calibration, residual errors remain (Figures 2, 3, 4) and these influence the usage of the data. The presence and approximate magnitudes of such errors can be identified in the ratio images of various bands of the global NIR data where color variations change across orbits and camera modes that cannot be attributed to surface materials (Figures 5 and 6). Though such color variations are less apparent in the frame corrected version of the NIR data, some residual patterns due to imperfect calibrations are known to exist in this version of the data as well. As a result, it may be useful to compare both versions of the NIR mosaics when conducting regional-scale analyses to identify local radiometric variations introduced by imperfect data calibrations. Due to the potential for such spatial variation in the radiometric calibrations, it is advantageous to conduct spectral analyses of the data over relatively large regions that include several different orbits and camera modes.

As mentioned earlier on this page, the full resolution NIR product will be available in early 2004. Please contact Chris Isbell (cisbell@usgs.gov) if you would like to receive archive copies of the implending systematically processed full resolution multi-volume set when it is released.

Top

---

References

Cahill, J.T., Lucey, P.G., Gillis, J.J., and Steutel, D., 2004, Verification of Quality and Compatibility for the Newly Calibrated Clementine NIR Data Set, Lunar Planet. Sci. XXXV, abstract 1469.

Eliason, E., C. Isbell, E. Lee, T. Becker, L. Gaddis, A. McEwen, M. Robinson, 1999, Mission to the Moon: The Clementine UVVIS Global Lunar Mosaic, PDS Volumes USA_NASA_PDS_CL_4001 through 4078, produced by the U.S. Geological Survey and distributed on CD media by the Planetary Data System.

Eliason, E.M., E.M. Lee, T.L. Becker, L.A. Weller, C.E. Isbell, M.I. Staid, L.R. Gaddis, A.S. McEwen, M.S. Robinson, T. Duxbury, D. Steutel, D.T. Blewett, and P.G. Lucey, 2003, A Near-Infrared (NIR) global multispectral map of the Moon from Clementine, Lunar Planet. Sci. XXXIV, abstract #2093.

Lucey, P.G., J. Hinrichs, E. Malaret, 1997, Progress toward Calibration of the Clementine NIR Camera Data Set, LPSC XXVII, pages 843-844.

Lucey, P.G., J. Hinrichs, C. Budney, G. Smith, C. Frost, B.R. Hawke, E. Malaret, M.S. Robinson, B. Bussey, T. Duxbury, D. Cook, P. Coffin, E. Eliason, T. Sucharski, A. McEwen, C.M. Pieters, 1998, Calibration of the Clementine Near Infrared Camera: Ready for Prime Time, LPS XXXI, Abstract #1576.

Lucey, P.G., D.T. Blewett, E. Eliason, L.A. Weller, R. Sucharski, E. Malaret, J.L. Hinrichs, and P.D. Owensby, 2000, Optimized calibration constants for the Clementine NIR camera, LPS XXIX, #1273.

McEwen A.S. and M. Robinson, 1997, Mapping of the Moon by Clementine, Adv. Space Res., 19, 1523-1527.

Nozette, S. and 33 others, 1994, The Clementine Mission to the Moon: Scientific Overview, Science, 266, 1835-1838.

Pieters, C. M. 1999, The Moon as a Spectral Calibration Standard Enabled by Lunar Samples: the Clementine Example, in New Views of the Moon II: Understanding the Moon Through the Integration of Diverse Datasets, September 22-24, 1999, Flagstaff, Arizona, abstract 8025.

Staid, M.I., Gaddis, L.R., and Isbell, C.E., 2004, Global Comparisons of Mare Volcanism from Clementine Near-Infrared Data, Lunar Planet. Sci. XXXV, abstract 1925.

Top

---

Contributors

M.I. Staid, C.E. Isbell, L.R. Gaddis, E.M. Eliason, E.M. Lee, T.L. Becker, L.A. Weller, J.R. Shinaman
USGS Astrogeology Research Program, 2255 N. Gemini Drive, Flagstaff, AZ

D. Steutel, P.G. Lucey, and J. Gillis
University of Hawaii, Honolulu, HI

A.S. McEwen
Lunar and Planetary Laboratory, University of Arizona, Tucson, AZ

M. S. Robinson
Northwestern University, Evanston, IL

T. Duxbury
Jet Propulsion Laboratory, Pasadena, CA

E. Malaret
Applied Coherent Technology, Herndon, VA

Brad Jolliff
Washington University, St. Louis, MO

Carle Pieters
Brown University, Providence, RI

Top

---

Resources

Related Astrogeology Topics & Pages

• Clementine Mission
• Earth's Moon
• Image Processing
• Images & Maps
• PDS Map-A-Planet

Related Web Sites

• NASA NSSDC: Clementine Project Information
• LPI: Clementine Mission Information
• JPL: PDS Clementine Navigator
• Northwestern: Clementine Lunar Images. See the Globl 5 band UVVIS Mosaics of the Moon for global color mosaics from the NASA PDS CD-ROMS formatted like the Clementine NIR distributed on this page.

Top