REPLACEMENT SENSOR MODEL (RSM) PERFORMANCE ... - asprs

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The same four ground control and nine tie points are used in the triangulation in the three scenarios that include triangulation. The off-nadir look angles for the images are about 37 degrees and 25 degrees. The stereo convergence angle for the two images is about 31 degrees. The GSDs are 0.55m to 0.62 m (measured normal to the line of sight). The replace/extract absolute CE statistics are around 5.1 m, within the specification of 6.5 m and the range of 4.0-5.5 m stated as a typical horizontal accuracy for WorldView images (at nadir, apart from terrain effects). The other scenarios, which include triangulation with control, have CE within the 2 m stated for WorldView images with control. Note that the ground control point accuracy has been estimated at one-meter (one-standard-deviation along all three axes), which is easily obtainable with GPS surveying. Prior to triangulation the errors between the ground control points are assumed to be uncorrelated. For all of the scenarios, the RSM performance is excellent in all respects, for both absolute and relative geopositioning. For absolute geopositioning, the statistics are over the four extracted points (9 tie points for the replace/triangulate scenario). For relative geopositioning, the statistics are over the six possible pairs of extracted points (36 tie point pairs for the replace/triangulate scenario). The largest differences in error estimates (absolute or relative CE or LE) for any of the tests is under 0.01 m. The largest solution differences (absolute or relative horizontal or vertical position) are about 0.04 m for the replace/triangulate scenario, where these differences are an insignificant 2 % or less of the corresponding error estimate. Table 9. Absolute geopositioning results for 2 WorldView images Scenario Statistic Original RSM Original RSM Horiz. Pos. Vert. Pos. CE (m) CE (m) LE (m) LE (m) diff. (m) diff. (m) Replace/Extract RMS 5.076 5.077 8.287 8.287 0.014 0.030 Max 5.136 5.136 8.307 8.313 0.014 0.030 Triangulate/ RMS 1.845 1.845 2.668 2.668 0.002 0.001 Replace/Extract Max 1.860 1.860 2.677 2.678 0.002 0.002 Replace/ RMS 1.846 1.846 2.687 2.686 0.011 0.016 Triangulate Max 1.889 1.888 2.733 2.731 0.024 0.038 Replace/ RMS 1.845 1.845 2.668 2.668 0.004 0.005 Triangulate/Extract Max 1.860 1.860 2.677 2.677 0.005 0.007 Table 10. Relative geopositioning results for 2 WorldView images Scenario Statistic Original CErel (m) RSM CErel (m) Original LErel (m) RSM LErel (m) ASPRS 2008 Annual Conference Portland, Oregon ♦ April 28 - May 2, 2008 Horiz. Rel. Pos. diff. (m) Vert. Rel. Pos. diff. (m) Replace/Extract RMS 1.981 1.981 3.227 3.227 0.001 0.000 Max 1.991 1.991 3.240 3.240 0.001 0.001 Triangulate/ RMS 1.979 1.979 3.227 3.227 0.001 0.000 Replace/Extract Max 1.991 1.991 3.240 3.239 0.001 0.001 Replace/ RMS 1.982 1.982 3.252 3.252 0.013 0.019 Triangulate Max 2.025 2.025 3.299 3.299 0.027 0.043 Replace/ RMS 1.979 1.979 3.227 3.227 0.003 0.004 Triangulate/Extract Max 1.991 1.991 3.240 3.239 0.004 0.005 Excellent RSM performance for triangulation and geopositioning has been seen in all of the WorldView scenarios in this section. These studies have been done with one stereo pair. Photogrammetric triangulations often involve many images, but all of the complexity of the problem is already present with two images, multiple tie points, and multiple ground control points, and these are very large images. CONCLUSION The tests conducted for this study show excellent agreement in triangulation and geopositioning between RSM and the rigorous commercial satellite sensor models they replace. Not only is the RSM projective model a very
good fit to the original, but the error estimates are very close, and the models perform virtually the same with triangulation adjustments. These results supplement earlier studies that demonstrated equally good performance for other types of imagery. In all of these studies, both the original and the RSM sensor models were used in the testbed to show the performance match. With each successful study, there is added confidence that a lean exploitation system with a single sensor model, RSM alone, is viable. The viability of the RSMSD format has received additional confirmation, since the testbed used it in every test to transmit the support data from the RSM Generator to the RSM Exploiter. The maturity of the RSM software development kits (Generator and Exploiter) has also received confirmation, since no modifications were made in the course of the study. The way forward for RSM is clear: RSMSD should now be generated and included in image products along with rigorous sensor model support data, to enable performance testing by the wider community, and the development of leaner, more robust and less expensive RSM-only exploitation systems. ACKNOWLEDGEMENTS We would like to thank Walter Scott and Milan Karspak of Digital Globe, Ed Mikhail of Purdue University, and Fidel Paderes, Reuben Settergren, Kevin Allen, Karen Diener, Randy Burt, Brian Highland, and Shannon McDonald of BAE Systems for their contributions to the RSM performance studies. REFERENCES Dolloff, J.T., 2004. Replacement Sensor Models, Chapter 11.3, Manual of Photogrammetry, 5th Edition, J. C. McGlone, Editor, ASPRS, pp. 887-943. Dolloff, J.T. and C.R. Taylor, 2004. Replacement Sensor Model Tagged Record Extensions Specification for NITF 2.1, http://www.gwg.nga.mil/ntb/coordinationitems/RSM%20TRE%20Appendix%20A_July_23_04.pdf. Dolloff, J.T. and C.R. Taylor, 2006. Proposed Updates to RSM TREs (Updates to the Replacement Sensor Model Tagged Record Extensions Specification for NITF 2.1, http://www.socetgxp.com/docs/products/special/pp_rsm_treupdates.pdf Dolloff, J.T., M.M. Iiyama, and C.R. Taylor, 2008. The Replacement Sensor Model (RSM): Overview, Status, and Performance Summary, ASPRS 2008 Annual Conference, April 28 - May 2, 2008 (forthcoming). Taylor, C.R., J.T. Dolloff, M.M. Iiyama, and E.M. Mikhail, 2006. RSM Extraction and Adjustment of Large Field of View Frame Imagery, http://www.socetgxp.com/docs/products/special/pp_rsm_largeformatframe.pdf. ASPRS 2008 Annual Conference Portland, Oregon ♦ April 28 - May 2, 2008
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REPLACEMENT SENSOR MODEL (RSM) PERFORMANCE ... - asprs

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