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School of Geography FACULTY OF ENVIRONMENT. GEOG5060 GIS & Environment. Dr Steve Carver Email: [email protected] 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
School of Geography

FACULTY OF ENVIRONMENT

GEOG5060 GIS & Environment

Dr Steve Carver

Email: [email protected]

lecture 7 terrain modelling geomorphometrics

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/

[email protected]

http://www.geog.leeds.ac.uk/people/a.turner/teaching/geog5060/2008/

course component
Course Component
  • Lecture
  • Workshop
  • Practical
  • Assignment
  • Assessment
slide4
Introduction

Basic metrics

Equidistant orthogonal comparisons

Other geomorphometrics

State of play

Lecture Outline

assignment
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
some assignment ideas
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
definition
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/

apologies and acknowledgement
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.

last 2 lectures
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

origins
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

overview
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.

raster elevation data
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

example dem
Example DEM

Red areas indicate high altitude, green low altitude

future dems
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

data pre processing
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

data pre processing continued
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...
recap
Geomorphometrics compare relative heights of cells

Allowing comparison of terrain, topology

Uncertainty is always present

Recap
basic metrics
Basic metrics

Slopeyness

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

Slope and Aspect
other metrics
Slopyness

Upness

Downess

Flatness

Roughness

Other metrics

Flatness calculated for the 2 cell neighbourhood

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

What region? How to calculate it?
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?

Scale and distance weighting
equidistant orthogonal comparisons
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
slide31
Axis based metrics

E4

A1

B1

B4

D4

C1

D1

E1

A4

C4

*

C2

A2

E3

D3

C3

D2

B2

B3

A3

E2

slide32
HLHL / LHLH

HHLL / LHHL / HLLH

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?

Considerations
axis based metrics
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

considerations1
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
other geomorphometrics
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

software
Proprietary or closed source

Commercial

Research

LandSerf

TauDEM

Open source

GMT

Grids

Software
slide44
Basic metrics

Equidistant orthogonal comparisons

Scale and distance weighting

Rotation invariant metrics

Scale and distance weighting - uncertainty

Summary

slide45
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

next week
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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