Applied Single GPS Point Statistical Analysis to Geometric Correction of Digital Satellite Imagery



To visualize possible errors, the team selected ten reading from the table for the remaining seven points, did the geometric correction, and overlapped the resulted grid over the mean grid to visualize the errors. Figure 4, shows all ten grids overlapped on the mean grid. It is the assumption of this paper that visualizing all the possible grids helps understand the nature of errors found in the original data.


Figure 4. The error grids overlapped the original mean grid in figure 3.

The procedure was repeated with other images. With the following two maps of Burj Al-Arab and Jabal Ali Dubai (Figure 5 and 6), the RMS was improved to a meter level. This paper noted that experience and selecting points at/close to sea level helped eliminating blunders and displacement effect.


Figure 5. An image map of Burj Al-Arab Area. (Source; IKONOS)



Figure 6. An image map of Jabal Ali, Dubai Area (Source; MAPSGeosystems)

Conclusion
Applied single GPS point spatial statistics to all the points showed a decimeter level accuracy. Geometric correction process was capable of weeding our blunders and show possible errors found among the point readings. Students of image processing can read tables and understand statistical measurements; still visualizing the grid error can provide a better understanding of the process and show the extent of errors that could happen from a single point reading.

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