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Geography 12: Maps and MappingLecture 23:

Photogrammetry and air photos for mapping

Some Definitions

• Photography: The art or process of producing images on a sensitized surface by the action of light or other radiant energy

• Image: A reproduction or imitation of the form of a view of objects

• Photo interpretation: The act of examining aerial photographs/images for the purpose of identifying objects and judging their significance

• Photogrammetry: The science or art of obtaining reliable measurements by means of photography

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1858 Photography takes to the air

• 1858 - Gasper Felix Tournachon"Nadar" takes the first aerial photograph from a captive balloon from an altitude of 1,200 feet over Paris

Wartime Advances• 1860's - Aerial observations, and possible

photography, for military purposes were acquired from balloons in the Civil War.

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Origins of Photogrammetry

• 1887 - Germans began experiments with aerial photographs and photogrammetrictechniques for measuring features and areas in forests

• 1889 - Arthur Batut take the first aerial photograph from using a kite of Labruguiere France

San Francisco1906 - George R. Lawrence

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The Great War• 1914 - Lt. Lawes, British Flying Service, takes what is thought

to be the first air photo over enemy territory in WWI• 1915 - Cameras especially designed for aerial use are being

produced. Brabazon designed and produced the first practical aerial camera

• 1918 - French aerial units developing and printing as many as 10,000 photographs each night.

• During the Meuse-Argonne offensive, 56,000 aerial prints were made and delivered to American Expeditionary Forces in four days

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Wartime technology turned elsewhere

• 1919 - Canadian Forestry Mapping Program begins• 1919 - Hoffman first to sense from an aircraft in thermal IR• 1920's First books on aerial photo interpretation begin to be

published• 1924 - Mannes and Godousky patent the first of their work of

multi-layer film which led to the marketing of Kodachrome in 1935

• 1931 - Stevens development of an IR sensitive film (B&W)• 1934 - American Society of Photogrammetry founded.

Photogrammetric Engineering first published.• 1936 - Captain Albert W. Stevens takes the first photograph of

the actual curvature of the earth - taken from a free balloon at an altitude of 72,000 feet

NHAP 1:80K (Wisconsin)

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U-2 & Francis Gary Powers

CORONA

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Photo Interpretation Tasks• Detection and identification of features, phenomena, or

processes– Detection and interpretation– Labeling– Confidence assessment

• Measurement and estimation• Use in topographic and special purpose mapping• Map update• Problem solving

– Object complexes– Object relations– Assessments/causes

• Rating of evidence– Assembly of information– Ranking and assessment

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Detection

Identification: What is it?

Source: www.mehs.educ.state.ak.us/ sitka/cross_sound.html

Sitka, Alaska

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Process

Process: Inference

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Inference: Sequence

Change detection

Bam City Japan. Digital Globe imagery Sept 03 and Jan 04 (Source: Tokyo Tech)

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Measurement

Orientation

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Spatial Resolution10cm, 25cm, 50cm, 1m

Resolution

* See mecca_saudi_arabia_quickbird_feb11_2003.tif

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Shape

Texture

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Pattern

Oblique Low Angle (no apparent horizon visible)

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Oblique Low Angle (cont.)

Oblique Low Angle (cont.)

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Overhead Vertical True

Oblique: High Angle CIR (apparent horizon visible)

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Oblique: High angle (apparent horizon visible)

Examples of High Oblique Photographs

Mozambique Flooding, March 2000

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Advantages of Vertical Aerial Photographs

• The scale is essentially constant.• Measurements of directions are easier than on

oblique photograph. Directions can also be measured more accurately.

• Within limits a vertical aerial photograph can be used as a map (if grids and marginal data are added).

• Vertical aerial photographs are often easier to interpret than oblique and are better for stereo (there is no masking).

Advantages of Oblique Aerial Photographs

• Given a constant altitude and camera you can cover a much larger area on a single photo.

• The view of some objects is more familiar to the interpreter.

• Some objects not visible on vertical photos may be seen on oblique.

• Oblique images may get results under weather

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Multi-lens mapping camera

UCSB Campus Orthophotography

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Chem Building: Nadir?

Control Point

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Motion blur

Storke Tower

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Outside Corwin

Goleta beach