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Lecture 7. Terrain analysis 3: geomatics; geomorphometrics

Lecture 7. Terrain analysis 3: geomatics; geomorphometrics. Andy Turner. Course component. Lecture Workshop Practical Assignment Assessment. Outline. Introduction Basic metrics Equidistant orthogonal comparisons Other geomorphometrics State of play. Assignment.

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Lecture 7. Terrain analysis 3: geomatics; geomorphometrics

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  1. Lecture 7.Terrain analysis 3: geomatics;geomorphometrics Andy Turner GEOG5060 - GIS and Environment

  2. Course component • Lecture • Workshop • Practical • Assignment • Assessment GEOG5060 - GIS and Environment

  3. Outline • Introduction • Basic metrics • Equidistant orthogonal comparisons • Other geomorphometrics • State of play GEOG5060 - GIS and Environment

  4. 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 adress some of the gaps I will mention – it really could be anything! GEOG5060 - GIS and Environment

  5. Definitions • Geomatics • Geomatics is a modern discipline, which integrates acquisition, modelling, analysis, and management of spatially referenced data, i.e. data identified according to their locations http://en.wikipedia.org/wiki/Geomatics • Geomorphometrics • Geomorphometrics are measures of the state and change in surface geometry of the Earth's physical 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/ GEOG5060 - GIS and Environment

  6. Idea for assignment • Develop wikipedia pages on geomorphometrics and link it to the geomatics wikipedia page • What other things are related? • Hydrology • Hydroinformatics • Surface water hydrology • Landform identification • Geomorphology - What combination of metrics can be used to identify different landforms? • What other than the standard offering would be useful? • You can even base your project on previous years work – ask me GEOG5060 - GIS and Environment

  7. height aspect slope hillshading plan curvature Featureextraction Last 2 Lectures • Terrain analysis 1 • DEMs and DTMs • derived variables • example applications • Terrain analysis 2 • access modelling • landscape evaluation • hazard mapping GEOG5060 - GIS and Environment

  8. 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 GEOG5060 - GIS and Environment

  9. 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. GEOG5060 - GIS and Environment

  10. Raster Elevation Data based • Raster Elevation Data • DEM data interpolated from vector data • Widely available • 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 GEOG5060 - GIS and Environment

  11. Example DEM Red areas indicate high altitude, green low altitude GEOG5060 - GIS and Environment

  12. Future DEMs • SRTM DEM data is being produced at a 1 arc second resolution • America is available • Soon after we will have higher resolution… • We have 10 meter resolution DEM for the UK… • Again hundreds of thousands of rows and columns • How was it produced? • Is it any good? • Soon we will have more higher spatial resolution GEOG5060 - GIS and Environment

  13. 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 GEOG5060 - GIS and Environment

  14. Data pre-processing contd. • Define the river basins, catchments and HRUs for the DEM • Develop land degradation risk indicators • Erosion • Salinity • Develop a fully distributed hydrological model GEOG5060 - GIS and Environment

  15. Recap • Geomorphometrics compare relative heights of cells • Allowing comparison of terrain, topology • Uncertainty is always present GEOG5060 - GIS and Environment

  16. Basic metrics Slopyness and Levelness calculated for the 2 cell neighborhood GEOG5060 - GIS and Environment

  17. Question • Can any one suggest the name of a basic geomorphometric? GEOG5060 - GIS and Environment

  18. Slope and Aspect • 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 GEOG5060 - GIS and Environment

  19. Other metrics • Slopyness • Upness • Downess • Flatness • Roughness Flatness calculated for the 2 cell neighbourhood GEOG5060 - GIS and Environment

  20. What region? How to calculate it? • 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 GEOG5060 - GIS and Environment

  21. Slope – 13 cell neighbourhood GEOG5060 - GIS and Environment

  22. Slope – 49 cell neighbourhood GEOG5060 - GIS and Environment

  23. Slope 8 GEOG5060 - GIS and Environment

  24. Aspect 2 GEOG5060 - GIS and Environment

  25. Aspect 4 GEOG5060 - GIS and Environment

  26. Aspect 8 GEOG5060 - GIS and Environment

  27. Scale and distance weighting • 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? GEOG5060 - GIS and Environment

  28. E4 A1 B1 B4 D4 C1 D1 E1 A4 C4 * C2 A2 E3 D3 C3 D2 B2 B3 A3 E2 Equidistant orthogonal comparisons • Rotation invariant metrics • For each metric, compare each orthoganal set within a region • What is observed? • hhhh, hhhl, hhll, llhl hlll, llll GEOG5060 - GIS and Environment

  29. E4 A1 B1 B4 D4 C1 D1 E1 A4 C4 * C2 A2 E3 D3 C3 D2 B2 B3 A3 E2 • Axis based metrics GEOG5060 - GIS and Environment

  30. HLHL / LHLH HHLL / LHHL / HLLH GEOG5060 - GIS and Environment

  31. HHHL - saddle GEOG5060 - GIS and Environment

  32. HHHH - crater GEOG5060 - GIS and Environment

  33. Geog 5060 GIS & Environment Lecture 7 HHLL - slope GEOG5060 - GIS and Environment

  34. LLLL - peak GEOG5060 - GIS and Environment

  35. Considerations • 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? GEOG5060 - GIS and Environment

  36. Example 1:w_hhll GEOG5060 - GIS and Environment

  37. Example 4:sumd_abs_xlxh_ai_lllh GEOG5060 - GIS and Environment

  38. E4 A1 B1 B4 D4 C1 D1 E1 A4 C4 * C2 A2 E3 D3 C3 D2 B2 B3 A3 E2 Axis based metrics • Profile or Contour • Concavity or Convexity • Convergence or Divergence GEOG5060 - GIS and Environment

  39. Considerations • 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! GEOG5060 - GIS and Environment

  40. 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 GEOG5060 - GIS and Environment

  41. Software used • Proprietary or closed source • Commercial • Research • LandSerf • TauDEM • Open source • GMT • Grids GEOG5060 - GIS and Environment

  42. Considerations • 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? GEOG5060 - GIS and Environment

  43. Other geomorphometrics • Up & down slope type geomorphometrics • Upslope area • Complex distance weighting • More hydrological type metrics • Flow accumulation • Visibility based metrics • Time and dynamics • Sensitivity & Monte Carlo type uncertainty of all GEOG5060 - GIS and Environment

  44. Summary • Basic metrics • Equidistant orthogonal comparisons • Scale and distance weighting • Rotation invariant metrics • Scale and distance weighting - uncertainty GEOG5060 - GIS and Environment

  45. Assignment • Show understanding of geomorphometrics • Experiment with the program in teams. Friday 2-4. • Develop an output of some sort and explain the processes you went through to produce it. GEOG5060 - GIS and Environment

  46. Next week… • Hydrological Modelling 1: • Catchment Models • With Katherine Arrell GEOG5060 - GIS and Environment

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