1. Peter Manning and Gary Margrave
Finite-difference modelling with correction filters in a variable velocity medium
Peter Manning and Gary Margrave
Introduction: uniform velocity corrections
Finite spatial correction filter examples
1D model correction example
2D model correction movies
Conclusions
Acknowledgements

2. Finite-difference time-stepping equation in 1D corrected
Correction factor in the box

3. Short filter spectrum
Ideal spectrum in blue

4. Short filter spectrum
Ideal spectrum in blue

5. Uncorrected/corrected comparison

6. Fine-uncorrected/corrected comparison
Fine model 1/2 sample rates of corrected

7. Uncorrected model
Movie

8. Corrected model
Movie

9. Uncorrected model
Last frame

10. Corrected model
Last frame

11. High velocity wedge model – displacement
Uncorrected

12. High velocity wedge model – displacement
Corrected

13. High velocity wedge model – displacement
Final frame - uncorrected

14. High velocity wedge model – displacement
Final frame - corrected

15. High velocity wedge model – P/T
Uncorrected

16. High velocity wedge model – P/T
Corrected

17. High velocity wedge model – P/T
Final frame - uncorrected

18. High velocity wedge model – P/T
Final frame - corrected

19. Conclusions
The ‘corrections’ developed in earlier papers may be approximated by small spatial filters.
Spatial filters may be applied to inhomogeneous velocity models, with good results.

20. Future work
Correction filters will be designed for a velocity range, so a limited set of filters may be applied to an arbitrary model.
More efficient computation methods will be investigated.

21. Acknowledgements
We would like to thank the CREWES sponsors for their generous support.