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Thursday, June 28, 2012

Transportation Defined: Aerial photography film

Aerial photographs are primarily used for map 
compilation for project assessments, 
design-level mapping and design concept reports. 
They may also be used at public hearings.
This item probably looks pretty familiar to any of you photography buffs out there. It’s a roll of film – a really big roll of film.

In fact, if you were to unroll it, the film would measure 9.5 inches by 250 feet!

But, what does this have to do with transportation, you might ask?

Remember yesterday when we blogged about Photogrammetry? We told you that the sophisticated maps created by ADOT photogrammetrists all start off as two aerial photographs.

The pair of aerial photos (called a stereomodel) is turned into a very accurate map that’s used for a number of purposes including helping engineers design roads.

Well, this is the film required to take those initial aerial photographs.

ADOT has a very large camera that is placed in an airplane specifically to get these aerial shots. After an area is flown and the photos are captured (about six exposures per mile for design level mapping), the film is developed.

The film is archived and kept in a
climate-controlled room.
Next, the very detailed photos are digitized by a powerful scanner (not your typical desktop scanner).

There’s a lot of information and detail in these photos so a large file size is required … one image equals about 267 megabytes for a black and white imagery.

From there, the digitized image is sent to the photogrammetrists so they can begin their work.

Transportation Defined is a series of explanatory blog posts designed to define the things you see on your everyday commute. Let us know if there's something you'd like to see explained ... leave a comment here on the blog or over on our Facebook page!
Posted by Angela DeWelles   |  Labels:  Aerial-Photo-Film, Transportation_Defined


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Civil RightsTitle VI of the Civil Rights Act of 1964, and the Americans with Disabilities Act (ADA)

Pursuant to Title VI of the Civil Rights Act of 1964, and the Americans with Disabilities Act (ADA), ADOT does not discriminate on the basis of race, color, national origin, age, sex or disability. Persons that require a reasonable accommodation based on language or disability should contact ADOT’s Civil Rights Office at 602.712.8946 or at [email protected]. Requests should be made as early as possible to ensure the State has an opportunity to address the accommodation.

De acuerdo con el título VI de la Ley de Derechos Civiles de 1964 y la Ley de Estadounidenses con Discapacidades (ADA por sus siglas en inglés), el Departamento de Transporte de Arizona (ADOT por sus siglas en inglés) no discrimina por raza, color, nacionalidad, edad, género o discapacidad.  Personas que requieren asistencia (dentro de lo razonable) ya sea por el idioma o por discapacidad deben ponerse en contacto con la Oficina de Derechos Civiles al 602.712.8946 o en [email protected]. Las solicitudes deben hacerse lo más pronto posible para asegurar que el equipo encargado del proyecto tenga la oportunidad de hacer los arreglos necesarios.