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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


Geog5060 gis environment

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


Question

Can any one suggest the name of another basic geomorphometric?

Question


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?


Slope 13 cell neighbourhood

Slope – 13 cell neighbourhood


Slope 49 cell neighbourhood

Slope – 49 cell neighbourhood


Geog5060 gis environment

Slope 8


Aspect 2

Aspect 2


Aspect 4

Aspect 4


Aspect 8

Aspect 8


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


Geog5060 gis environment

Axis based metrics

E4

A1

B1

B4

D4

C1

D1

E1

A4

C4

*

C2

A2

E3

D3

C3

D2

B2

B3

A3

E2


Geog5060 gis environment

HLHL / LHLH

HHLL / LHHL / HLLH


Geog5060 gis environment

HHHL - saddle


Geog5060 gis environment

HHHH - crater


Geog5060 gis environment

Geog 5060 GIS & Environment Lecture 7

HHLL - slope


Geog5060 gis environment

LLLL - peak


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


Example 1 w hhll

Example 1:w_hhll


Example 4 sumd abs xlxh ai lllh

Example 4:sumd_abs_xlxh_ai_lllh


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


Geog5060 gis environment

Basic metrics

Equidistant orthogonal comparisons

Scale and distance weighting

Rotation invariant metrics

Scale and distance weighting - uncertainty

Summary


Geog5060 gis environment

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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