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GEOG5060 GIS & Environment

School of Geography FACULTY OF ENVIRONMENT. GEOG5060 GIS & Environment. Dr Steve Carver Email: S.J.Carver@leeds.ac.uk. Lecture 7: Terrain modelling – geomorphometrics. http://www.geog.leeds.ac.uk/people/a.turner/teaching/geog5060/2008/. Andy Turner

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GEOG5060 GIS & Environment

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  1. School of Geography FACULTY OF ENVIRONMENT GEOG5060 GIS & Environment Dr Steve Carver Email: S.J.Carver@leeds.ac.uk

  2. Lecture 7: Terrain modelling – geomorphometrics • http://www.geog.leeds.ac.uk/people/a.turner/teaching/geog5060/2008/ Andy Turner http://www.geog.leeds.ac.uk/people/a.turner/ A.G.D.Turner@leeds.ac.uk http://www.geog.leeds.ac.uk/people/a.turner/teaching/geog5060/2008/

  3. Course Component • Lecture • Workshop • Practical • Assignment • Assessment

  4. Introduction Basic metrics Equidistant orthogonal comparisons Other geomorphometrics State of play Lecture Outline

  5. Assignment • This part of the course is about working together to improve our teaching and research on geomorphometrics • During the lecture consider areas in which you could address some of the gaps I will mention • I am asking you to contribute and develop this part of the course • Your contribution really could be anything! • I am also keen for you to collaborate and work together in groups or en masse

  6. Some assignment ideas • Update wikipedia or other encyclopedia type web content • http://www.wikinfo.org/index.php/Geomorphometrics • http://www.wikipedia.org/wiki/Geomorphometrics • Improve course materials • Contribute a research article based on applied or investigative work • Develop software • Results visualiser • Graphical User Interface

  7. Definition Geomorphometrics are measures of the state and change in surface geometry of geophysical horizons. They are topographic measures that can be used in terrain analysis and geographical modelling. http://www.geog.leeds.ac.uk/people/a.turner/research/interests/geomorphometrics/

  8. Apologies and acknowledgement Last night I spent hours developing these lecture slides only to lose most of the work I am probably more annoyed by this than you will be Hopefully you won’t suffer as much as me as a consequence What follows are some slides developed by some in the class of 2007 with a new template applied and jiggled around a bit so you can see all the various images and text.

  9. Last 2 Lectures Terrain analysis 1 DEMs and DTMs derived variables example applications Terrain analysis 2 access modelling landscape evaluation hazard mapping height aspect slope hillshading plan curvature Featureextraction

  10. Origins Peter Fisher Peakiness Development of a grids package The SPIN!-project MedAction, DesertLinks and tempQsim Desire for greater flexibility, capability and freedom than that offered by commercial proprietary GIS

  11. Overview So what are geomorphometrics? Measures of the relative heights of the land of the earth’s surface to allow comparison of: Topography Terrain analysis e.g. how peaky is an area? Surface geometry of the earth.

  12. Raster Elevation Data DEM data interpolated from vector data Widely available for many planets and regions of Earth SRTM 3 arc secs Publicly available OS 10 metre Available via chest LIDAR 2 meter Available but unlicensed Getting better all the time Uncertainties abound

  13. Example DEM Red areas indicate high altitude, green low altitude

  14. Future DEMs Higher spatial resolution Larger regions More values Larger ranges More detailed precision 3D spatial Temporal change Hundreds of thousands of millions of data points

  15. Data pre-processing One of the first things to do is to be able to process all this data Grids 1.0 beta Clean the data Mask Are there any holes? How can we cope best with these

  16. Define the river basins, catchments and HRUs for the DEM Develop land degradation risk indicators Erosion Salinity Develop a fully distributed hydrological model Data pre-processing continued...

  17. Geomorphometrics compare relative heights of cells Allowing comparison of terrain, topology Uncertainty is always present Recap

  18. Basic metrics Slopeyness

  19. Can any one suggest the name of another basic geomorphometric? Question

  20. Slope is the gradient of an area http://en.wikipedia.org/wiki/Slope and aspect is the angle to a particular orientation over a given region http://en.wikipedia.org/wiki/Aspect_%28geography%29 Slope and Aspect

  21. Slopyness Upness Downess Flatness Roughness Other metrics Flatness calculated for the 2 cell neighbourhood

  22. Circular region using equidistant orthoganal comparisons Vector addition Distance weighting Scale NB From the model output white regions indicate areas of high values for that metric What region? How to calculate it?

  23. Slope – 13 cell neighbourhood

  24. Slope – 49 cell neighbourhood

  25. Slope 8

  26. Aspect 2

  27. Aspect 4

  28. Aspect 8

  29. Distance weighting Differencing to focus on nid-scales can be done directly by applying a more complex spatial weighting scheme Only relevant for some measures Not aspect What about upness and downness? Scale and distance weighting

  30. Equidistant orthogonal comparisons Rotation invariant metrics E4 A1 B1 B4 D4 C1 D1 E1 A4 C4 * C2 A2 E3 D3 C3 D2 B2 B3 A3 E2 • For each metric, compare each orthoganal set within a region • What is observed? • hhhh, hhhl, hhll, llhl hlll, llll

  31. Axis based metrics E4 A1 B1 B4 D4 C1 D1 E1 A4 C4 * C2 A2 E3 D3 C3 D2 B2 B3 A3 E2

  32. HLHL / LHLH HHLL / LHHL / HLLH

  33. HHHL - saddle

  34. HHHH - crater

  35. Geog 5060 GIS & Environment Lecture 7 HHLL - slope

  36. LLLL - peak

  37. How to treat cells with the same height? How to treat cells with no data value? What conditioners are appropriate? Two types of weight Distance weighting Difference in elevation weighting What is best? Considerations

  38. Example 1:w_hhll

  39. Example 4:sumd_abs_xlxh_ai_lllh

  40. Profile or Contour Concavity or Convexity Convergence or Divergence Axis based metrics E4 A1 B1 B4 D4 C1 D1 E1 A4 C4 * C2 A2 E3 D3 C3 D2 B2 B3 A3 E2

  41. What other interesting metrics? minimum type profile concavity maximum type profile convexity Better for identifying features? Probably best in combination with the other metrics Sorry, no examples! Considerations

  42. Other geomorphometrics Up and down slope type geomorphometrics Upslope area Complex distance weighting More hydrological type metrics Flow accumulation Visibility based metrics Monte Carlo type uncertainty of all

  43. Proprietary or closed source Commercial Research LandSerf TauDEM Open source GMT Grids Software

  44. Basic metrics Equidistant orthogonal comparisons Scale and distance weighting Rotation invariant metrics Scale and distance weighting - uncertainty Summary

  45. Practical Experiment with a program to generate geomorphometrics in teams Friday 12:00 to 16:00 in Masters computing room, Geography East Building. Develop an output of some sort and explain the processes you went through to produce it. Assignment Show understanding of geomorphometrics and develop the subject Next Steps

  46. Next week… • Hydrological modelling 1: catchment models • Basics of hydrology • Creating hydrologically correct DEMs • Modelling catchment variables • Workshop: Catchment modelling in GRID • Practical: Catchment modelling

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