Remote Sensing

Introduce to Aerial Photography

Bismillahirrahmanirrahiim…

Now I want to share about aerial photography.

Aerial photographs have been a main source of information about what is at the Earth’s surface almost since the beginning of aviation more than 100 years ago. Until space imagery, these photos were the principal means by which maps are made of features and spatial relationships on the surface. Cartography, the technology of mapping, depends largely on aerial/satellite photos/images to produce maps in two dimensions or three. Aerial photos are obtained using mapping cameras that are usually mounted in the nose or underbelly of an aircraft that then flies in discrete patterns or swathes across the area to be surveyed.

This type uses separate lenses, each with its own narrow band color filter, that are opened simultaneously to expose a part of the film inside the camera. Here is one such camera for use in aerial photography.used by PT. Zasuko Info join Karvak Nusa Geomatica in its remote sensing programs:

Aerial photos are taken from a variety of platforms: airplanes; helicopters; unmanned drones; balloons; kites; tall buildings. For the most common platform – airplanes – most cameras are mounted in the underside of the aircraft. Propeller or JetProp aircraft are preferred, for two reasons: 1) they fly slower, allowing easier film advance; 2) they cost less to operate. This photo shows two such aircraft used by PT. Zasuko Info join Karvak Nusa Geomatica in its remote sensing programs:

Below picture show us another platform in aerial photography

www.photogrammetry.ethz.ch
TLS System Outside. Source:www.photogrammetry.ethz.ch
The TLS Camera is equipped with a stabilizer and mounted together on an arm outside an aircraft in case of a helicopter
The TLS Camera is equipped with a stabilizer and mounted together on an arm outside an aircraft in case of a helicopter
Camera in cabin
Camera in cabin
Four CCD line sensor packages are placed parallel to each other into the focal plane of the camera lens system. Three packages (out of the four) serve as forward, nadir and backward viewing sensors. Each of them consists of three line sensors, generating R (Red), G (Green) and B (Blue) images to be combined into color images. In addition, there is another CCD package for a near infrared (NIR) image between the backward and the nadir CCD packages. Each line sensor can produce a high-resolution, two-dimensional image during the flight, generating 10 images in total and simultaneously, which overlap 100% with each other.
Four CCD line sensor packages are placed parallel to each other into the focal plane of the camera lens system. Three packages (out of the four) serve as forward, nadir and backward viewing sensors. Each of them consists of three line sensors, generating R (Red), G (Green) and B (Blue) images to be combined into color images. In addition, there is another CCD package for a near infrared (NIR) image between the backward and the nadir CCD packages. Each line sensor can produce a high-resolution, two-dimensional image during the flight, generating 10 images in total and simultaneously, which overlap 100% with each other
With Stabilizer and Without Stabilizer
Without Stabilizer and With Stabilizer

Another placement of camera in aerial photography, in case helicopter.

3D Aerial Image

In 3D aerial photography, we look image in three dimension.

Low view on rendered 3d model, with filled line style and aerial-photo textures draped on top.
Low view on rendered 3d model, with filled line style and aerial-photo textures draped on top.
Isometric view with the 3d buildings on top of the aerial photo.  The models can be switched on or off by demand
Isometric view with the 3d buildings on top of the aerial photo. The models can be switched on or off by demand
Close view with all the textures very well visible
Close view with all the textures very well visible
All the details are measured with an accuracy around the 6 cm in Z-axis
All the details are measured with an accuracy around the 6 cm in Z-axis

Image source : http://www.photogrammetry.eu

Digital Photogrammetry

The digital, or soft copy, photogrammetry systems are much simpler in design than the analytical systems; they consist of a computer with a stereo-capable graphics system, 3-D glasses with electronic shutters, and a “3-D mouse” as a user interface. The 3-D mouse is a reconfigured optical mouse with x, y, and z motion control and several user-configurable buttons. All other hardware of an analytical system has been replaced with software programming, alleviating the problems with mechanical devices wearing out or needing adjustments to stay within close tolerances.

pubs.usgs.gov
Digital or “soft copy” photogrammetry workstation using VrTwo software, showing stereo glasses and “3-D mouse”. Source: pubs.usgs.gov

Examples of Aerial Photos

An aerial photo is just a black and white (b & w) or color “picture” of an area on the Earth’s surface (plus clouds), either on print or in a transparency, obtained by a film or digital camera located above that surface. This camera shoots the picture from a free-flying platform (airplane, helicopter, kite or balloon) some preplanned distance above the surface. Two types depend on the angle of view relative to the surface. The first, oblique photography, snaps images from a low to high angle relative to vertical. The example below is the most common type (high oblique)

SUNRISE GLACIER at MISSION MOUNTAINS
SUNRISE GLACIER at MISSION MOUNTAINS. Collected by helicopter
Screenshot showing geologic features digitized on the 3-D photographic surface in VrTwo software.
Screenshot showing geologic features digitized on the 3-D photographic surface in VrTwo software. Source: pubs.usgs.gov
24.000
Natural Color 1:24.000
8.000
Color IR 1:8.000

Hope you enjoy this blog and increase your knowledge about Geo-Spatial Technology…

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