Methods and interpretation of aerial photography and topography for geomorphic studies

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Methods and interpretation of aerial photography
(and topography) for geomorphic studies
Overview of approach and data types Erin DiMaggio
guest lecture
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Power of remote sensing objective
multi-resolution, multispectral, and
multitemporal views of planetary surfaces
Lots of data out there http//rsd.gsfc.nasa.gov/r
sd/RemoteSensing.html Recent, color (visible),
hi resolution in Google Earth
http//www.ucalgary.ca/UofC/faculties/SS/GEOG/Virt
ual/remoteintro.html
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Electromagnetic spectrum and sensors Visible
topography Near IR vegetation and surfaces
(pavement, active erosion) NIR TIR rock
composition mapping RADAR (far to right)
surface roughness and range (incl. Change)
active remote sensing
Landsat 7 spectral bands
http//landsat.gsfc.nasa.gov
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LANDSAT spectral band combinations for the
greater Phoenix area, Arizona, USA
When and why do you use different band
combinations?
S. Wood
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SESE Remote Sensing classes

• SESE 490/598 Remote sensing with Phil Christensen
• Also Advanced Remote Sensing
• ASM498/GPH591/GLG598/GLG490 Remote Sensing and
  Quaternary Landscapes (2006 Spring)

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Aerial photography

• Powerful applications for geomorphology

Geometry of photography
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Look at cooling towers Relief displacement as
example of parallax which is distortion that we
can use
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Basic elements of vertical photograph and effect
of topography on airphoto geometry versus map
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Stereoscopic viewing/analysis Uses parallax
between offset pictures of the same feature to
sense 3D. You should try to learn to do it
unaided.
http//www.hdic.jmu.edu/sic/content/rs_interpretin
g.html
http//www.icpowercontrols.com/3DStereoAerialPhoto
graphy.html
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Concept of Photogrammetry
Parallax An apparent change in the direction of
an object, caused by a change in observational
position that provides a new line of sight.
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Examples of 9x9 aerial photos
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Application of Aerial Photography Creating DEMs
using Erdas Imagine LPS

• Aerial Photographs with 60 overlap
• Define Camera parameters, spatial reference,
  fiducial marks..etc.
• Choose GCPs
• Control points (x,y,z)
• check points (x,y,z)
• tie points (auto-generated)
• Aerial Triangulation (assess accuracy of
  correlation)
• Creates a mathematical relationship between the
  images
• Terrain Extraction
• Parameters for extraction (resolution, terrain
  type, excluded areas)
• Terrain Editor
• Add/Delete/Modify mass points of the TIN
• add more detail in specific areas -
• remove artifacts from automatic DEM production

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30m hillshade
Carrizal Fault, near La Paz, Baja California Sur,
Mexico
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3m hillshade
Carrizal Fault, near La Paz, Baja California Sur,
Mexico
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PED map1 draped over dem
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PED map draped over dem
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Mapping and image interpretation
Basic considerations for interpretation

• Shape general form, configuration, outline of
  individual objects.
• Size consider in context of image scale
• Pattern spatial arrangement of objects (e.g.,
  orchard)
• Tone relative brightness or color of objects on
  an image
• Texture frequency of tonal change (smoothness or
  coarseness)
• Shadows gives profile view of object and implies
  relative heights
• Site refers to geographic or topographic
  location what do you expect to be there?
• Association occurrence of certain features in
  relation to others
• Resolution what is the finest thing you can see?
• Targets identify main features you want to
  emphasize on your map

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Mapping

• Geomorphic mapping
• Important means of establishing landforms, their
  distributions and relations to each other,
  process distributions, and history
• Quaternary geologic mapping
• Emphasis on young deposits and landforms that are
  usually lumped into one unit in bedrock mapping.
  Uses both the deposit characteristics as well as
  the landform shape and position in the landscape
  as criteria for unit designation.
• I cannot work on anything unless I map it first!

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Ramóns Mapping Mantras

• Scale If your pencil is 0.5 mm in diameter, how
  big on the ground is it if you are mapping on a
  124,000 scale map? How about on a 1500,000
  map?
• Even coverage if there is blank space, you did
  not look there.
• Strive to provide detail. Do not generalize.

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Ramóns Mapping Mantras

• All lines mean something.
• Consistent notation and symbology.
• Quality control. Use dashing, variable line
  weights, queries. If something is uncertain or
  approximate, indicate so.
• Data/ink ratio-gt 1. Put emphasis on important
  things (data) by putting relatively more ink in
  themgreater line weights, larger text., etc.
• Neatness counts.

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Edward Tufte, Envisioning Information
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Geomorphic mapping of the Penaguila region in SE
Spain
Erin DiMaggio Ramón Arrowsmith
May 17th 2006
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Penaguila Overview

• Goals
• Use aerial photography in stereo to map
  Quaternary geomorphology in order to understand
  the distribution of and relationships between
  identified landforms
• special attention to terrace surfaces
• Create a high-resolution DEM (using ERDAS Imagine
  Leica Photogrammetry Suite) to aid in the
  identification, correlation and reconstruction of
  terraces.
• Model spatial and temporal variations in erosion
  intensity that can be used to indicate regions of
  landscape modification (model validation)
• Purposes
• Identify prominent landscape processes
• Assess the stability of surfaces for quantitative
  assessments
• Define the late Quaternary landscape
• Recognize high erosion hot spots that will be
  sensitive areas for modeling
• What processes are really driving change in this
  region?
• Correlation (feedback?) between processes
  archaeology

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Geomorphology Terrace Mapping

• Methods
• Map geomorphology and terraces using stereo
  aerial photos (110,000)--prototype
• Extract mapped and digitized terrace polygons
  from a high resolution DEM
• Interpolate a landscape across correlative
  terraces polygons
• Subtract grids from the original DEM to locate
  and quantify erosion
• Create a model of erosion through space and
  relative time by filling in terraces surfaces
  to modern DEM
• Look at spatial variation in erosion potential
• Do we see visible landscape change between
• 
  54 and 84?
• Need to bring in other information
• Soils
• Archaeology
• Field Work
• -real terraces?
• -relationships between terrace levels
• -description of terrace surfaces
• -age control
• -soil profiles

• Issues
• Correlation of high elevation terraces
• Soils map resolution
• Erosion rates need age control

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Aerial Photo ASTER visible (3-2-1)
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Geomorphology Mapping
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Terrace and Landform Mapping
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Geomorph Terrace Maps