Remote Sensing and Sensors

Remote Sensing

An Introduction
Remote Sensing is the science and art of acquiring information (spectral, spatial, temporal) about material objects, area, or phenomenon, without coming into physical contact with the objects, or area, or phenomenon under investigation. Without direct contact, some means of transferring information through space must be utilised. In remote sensing, information transfer is accomplished by use of electromagnetic radiation (EMR). EMR is a form of energy that reveals its presence by the observable effects it produces when it strikes the matter. EMR is considered to span the spectrum of wavelengths from 10-10 mm to cosmic rays up to 1010 mm, the broadcast wavelengths, which extend from 0.30-15 mm.

Types

1. In respect to the type of Energy Resources:
   Passive Remote Sensing: Makes use of sensors that detect the reflected or emitted electro-magnetic radiation from natural sources.
   
   Active remote Sensing: Makes use of sensors that detect reflected responses from objects that are irradiated from artificially-generated energy sources, such as radar.
2. In respect to Wavelength Regions:
   
   Remote Sensing is classified into three types in respect to the wavelength regions
• Visible and Reflective Infrared Remote Sensing.
• Thermal Infrared Remote Sensing.
• Microwave Remote Sensing.

Famous Remote Sensing Sensors and Characteristic of them

About the IKONOS Satellite

The IKONOS Satellite is a high-resolution satellite operated by GeoEye. Its capabilities include capturing a 3.2m multispectral, Near-Infrared (NIR)/0.82m panchromatic resolution at nadir. Its applications include both urban and rural mapping of natural resources and of natural disasters, tax mapping, agri

culture and forestry analysis, mining, engineering, construction, and change detection. It can yield relevant data for nearly all aspects of environmental study. IKONOS images have al

so been procured by SIC for use in the media and motion picture industries, providing aerial views and satellite photos for many areas around the world.

IKONOS Satellite System: Sensor Characteristics

Launch Date	24 September 1999 at Vandenberg Air Force Base, California, USA
Operational Life	Over 7 years
Orbit	98.1 degree, sun synchronous
Speed on Orbit	7.5 kilometers per second
Speed Over the Ground	6.8 kilometers per second
Revolutions Around the Earth	14.7, every 24 hours
Altitude	681 kilometers
Resolution at Nadir	0.82 meters panchromatic; 3.2 meters multispectral
Resolution 26° Off-Nadir	1.0 meter panchromatic; 4.0 meters multispectral
Image Swath	11.3 kilometers at nadir; 13.8 kilometers at 26° off-nadir
Equator Crossing Time	Nominally 10:30 AM solar time
Revisit Time	Approximately 3 days at 40° latitude
Dynamic Range	11-bits per pixel
Image Bands	Panchromatic, blue, green, red, near IR

GeoEye-1 Satellite Sensor

The GeoEye-1 Satellite sensor was developed by GeoEye and features the most sophisticated technology ever used in a commercial remote sensing system.

GeoEye-1 is capable of acquiring image data at 0.41 meter panchromatic (B&W) and 1.65 meter multispectral resolution. It also features a revisit time of less than three days, as well as the ability to locate an object within just three meters of its physical location.

This newly developed sensor is optimized for large projects, as it can collect over 350,000 square kilometers of pan-sharpened multispectral satellite imagery every day.

GeoEye-1: Satellite Sensor Characteristics

The following specifications are courtesy of GeoEye, and are subject to change.

IMAGING & COLLECTION SPECIFICATIONS

Launch Date	September 6, 2008 11:50:57 to 11:52:21 AM PST
Camera Modes	• Simultaneous panchromatic and multispectral (pan-sharpened) • Panchromatic only • Multispectral only
Resolution	0.41 m / 1.34 ft* panchromatic (nominal at Nadir) 1.65 m / 5.41 ft* multispectral (nominal at Nadir)
Metric Accuracy/Geolocation	CE stereo: 2 m / 6.6 ft LE stereo: 3 m / 9.84 ft CE mono: 2.5 m / 8.20 ft These are specified as 90% CE (circular error) for the horizontal and 90% LE (linear error) for the vertical with no ground control points (GCP's)
Swath Widths & Representative Area Sizes	• Nominal swath width - 15.2 km / 9.44 mi at Nadir • Single-point scene - 225 sq km (15x15 km) • Contiguous large area - 15,000 sq km (300x50 km) • Contiguous 1° cell size areas - 10,000 sq km (100x100 km) • Contiguous stereo area - 6,270 sq km (224x28 km) (Area assumes pan mode at highest line rate)
Imaging Angle	Capable of imaging in any direction
Revisit Frequency at 684 km Altitude (40° Latitude Target)	Max Pan GSD (m) Off Nadir Look Angle (deg) Average Revisit (days) 0.42 10 8.3 0.50 28 2.8 0.59 35 2.1
Daily Monoscopic Area Collection Capacity	Up to 700,000 sq km/day (270,271 sq mi/day) of pan area.

About the QuickBird Satellite Sensor

QuickBird is a high resolution satellite owned and operated by DigitalGlobe. Using a state-of-the-art BGIS 2000 sensor (PDF), QuickBird collects image data to 0.61m pixel resolution degree of detail. This satellite is an excellent source of environmental data useful for analyses of changes in land usage, agricultural and forest climates. QuickBird's imaging capabilities can be applied to a host of industries, including Oil and Gas Exploration & Production (E&P), Engineering and Construction and environmental studies

QuickBird Satellite Sensor Characteristics

Launch Date	October 18, 2001
Launch Vehicle	Boeing Delta II
Launch Location	Vandenberg Air Force Base, California, USA
Orbit Altitude	450 Km
Orbit Inclination	97.2°, sun-synchronous
Speed	7.1 Km/sec (25,560 Km/hour)
Equator Crossing Time	10:30 AM (descending node)
Orbit Time	93.5 minutes
Revisit Time	1-3.5 days, depending on latitude (30° off-nadir)
Swath Width	16.5 Km x 16.5 Km at nadir
Metric Accuracy	23 meter horizontal (CE90%)
Digitization	11 bits
Resolution	Pan: 61 cm (nadir) to 72 cm (25° off-nadir) MS: 2.44 m (nadir) to 2.88 m (25° off-nadir)
Image Bands	Pan: 450-900 nm Blue: 450-520 nm Green: 520-600 nm Red: 630-690 nm Near IR: 760-900 nm