HRS Camera

The HRS instrument mounted on the satellite, next to the VEGETATION instrument

Operating principle and optical path

The HRS instrument is designed to acquire images in the panchromatic band at viewing angles of 20° forward and aft of the satellite. It can thus obtain stereopair images quickly to generate digital elevation models.

HRS uses the same pushbroom scanning technique as HRG

HRS instrument architecture

The HRS instrument consists of:

• A carbon-skin sandwich/aluminium honeycomb instrument panel supporting the mechanical interface with the SPOT 5 satellite and the instrument systems.
• A stereo video module (MVS), which handles and processes data from the detection units, actively controls the instrument’s temperature and provides the ancillary systems required to operate it (chiefly power and TM/TC).
• A thermal cocoon encloses the temperature-sensitive components vital to achieve the instrument’s required performance, i.e.:
  · The front and rear objectives, mounted on a quasi-isostatic structure to ensure stability. The objectives collect incoming light in the panchromatic band and focus it onto the lines of detectors. It filters out all rays outside the panchromatic band to minimize stray light.
  · The front and rear detection units, which house the CCD sensors and electronics. These units convert the light signal into anelectrical signal
  

The HRS instrument during integration in October 2000

The cocoon maintains the instrument's components within the required temperature range.

HRS instrument during tests

Source: http://spot5.cnes.fr/

Technical data

HRS technical data
Mass	90 kg
Power	128 W
Dimensions	1×1,3×0,4 m
Field of view	+/- 4°
Focal lenght	0.580 m
Detectors per line	12000
Detector pitch	6.5 µm
Integration time per line	0.752 ms
Forward/aft viewing angle	+/-20°
Performance
Spectral range (panchromatic band)	0.48 µm – 0.70 µm
Ground sample distance Across track Along track	10 m 5 m
Modulation transfer function	> 0.25
Signal-to-noise ratio	> 120

Introduction to SPOT

SPOT5

The SPOT (Systeme Provatoire d’Observation de la Terre), program, developed in France with the collaboration of Belgium and Sweden.

SPOT5 is the latest of the SPOT series of satellites continuing and complementing the mission assigned to its predecessors in the field of Earth Observation and Mapping. Launched on May 2002 the 3rd, its in-flight commissioning was led in two phases. The qualification phase permitted to hand over the satellite to Spot Image in july 2002 [Bouillon 2002,2003], [Breton 2002]. The second phase included fine tuning of its components and continued until early 2003 allowing to fully take advantage of the geometric improvements brought to SPOT5 compared to its elders :

- star tracker and improved steering mirror on HRG instruments for the localization,

- monolithic CCD array,

- resolution,

- along track stereoscopic instrument HRS.

Observations on the first SPOT 5 images showed imperfections in the CCD array and telescop alignments both on HRG and HRS instruments. An inner orientation of the instruments was therefore considered necessary, especially for

the HRS stereoscopic instrument with an optical distorsion of several pixels. Following is a non exhaustive list of the

outcomes expected from this inner orientation :

- assessed and refined look angle models provided by the satellite constructor ;

- optimized relative orientation between the forward and backward HRS stereoscopic instruments ;

- optimized relative orientation between the panchromatic and multispectral bands within each HRG instrument.

On previous SPOT satellites the geometric performance of the detectors has been assessed with relative methods Valorge 2003] involving simultaneous acquisitions of the same scene with both instruments ; these methods never permitted to obtain an absolute measurement of the viewing direction [Gachet 1999]. The characteristics of SPOT5 instruments together with the objective of inner orientation made it necessary to implement another method based on absolute calibration using airborne images and elevation information from our « super site » in southeastern France. Since March 2003, ancillary data provided in the « METADATA.DIM » file associated with SPOT5 images [Spot Image 2002] include the instruments look angles for each detector with an estimated RMS accuracy of 0.03 pixel.

About the SPOT-5 Satellite Sensor

The SPOT-5 Earth observation satellite was successfully placed into orbit by an Ariane 4 from the Guiana Space Centre in Kourou during the night of 3 to 4 May 2002.

The VEGETATION 2 passenger instrument on SPOT-5 also provides continuity of environmental monitoring around the globe, like its predecessor on SPOT-4.

SPOT Image Corporation is composed of four subsidiaries, including an office in Germany and a dense global network of receiving stations, channel partners, and distributors. Satellite Imaging Corporation is an official distributor for SPOT Image Corporation.

Compared to its predecessors, SPOT-5 offers greatly enhanced capabilities, which provide additional cost-effective imaging solutions. Thanks to SPOT-5’s improved 5-metre and 2.5-metre resolution and wide imaging swath, which covers 60 x 60 km or 60 km x 120 km in twin-instrument mode, the SPOT-5 satellite provides an ideal balance between high resolution and wide-area coverage. The coverage offered by SPOT-5 is a key asset for applications such as medium-scale mapping (at 1:25 000 and 1:10 000 locally), urban and rural planning, oil and gas exploration, and natural disaster management. SPOT-5’s other key feature is the unprecedented acquisition capability of the on-board HRS stereo viewing instrument, which can cover vast areas in a single pass. Stereo pair imagery is vital for applications that call for 3D terrain modeling and computer environments, such as flight simulator databases, pipeline corridors, and mobile phone network planning.

Archived and New SPOT-5 Imagery

For many image requests, a matching image can already be located in the archives of SPOT-5 imagery from around the world. If no image data is available in the archives, new SPOT-5 satellite image data can be acquired through a satellite tasking process. Besides providing image data, Satellite Imaging Corporation also performs many tasks in the background to ensure that we meet customer specifications and time schedules. We:

• Negotiate the attainment of archived or new images
• Process imagery, including orthorectification, DSMs, DTMs, and culture and terrain extraction for GIS
• Incorporate third-party United States and international GIS data
• Consult on band combinations most appropriate to bring out the geographical and manmade features that are most relevant to your project
• Perform spectral analysis for landcover use classifications and environmental changes

Source: SPOT Satellite Geometry Handbook

SPOT-5 Satellite Sensor Characteristics

Launch Date	May 3, 2002
Launch Vehicle	Ariane 4
Launch Location	Guiana Space Centre, Kourou, French Guyana
Orbital Altitude	822 kilometers
Orbital Inclination	98.7°, sun-synchronous
Speed	7.4 Km/second (26,640 Km/hour)
Equator Crossing Time	10:30 AM (descending node)
Orbit Time	101.4 minutes
Revisit Time	2-3 days, depending on latitude
Swath Width	60 Km x 60 Km to 80 Km at nadir
Metric Accuracy	< 50m horizontal position accuracy (CE90%)
Digitization	8 bits
Resolution	Pan: 2.5m from 2 x 5m scenes Pan: 5m (nadir) MS: 10m (nadir) SWI: 20m (nadir)
Image Bands	Pan: 480-710 nm Green: 500-590 nm Red: 610-680 nm Near IR: 780-890 nm Shortwave IR: 1,580-1,750 nm

ColorEnhance Wizards ER Mapper 7.0

ColorEnhance Wizards

Colordrape wizard

Create several different types of colordrape images, or images that combine color with shaded relief. This wizard gives you fast access to many different combinations and options. Typical input data types includes DEMs, bathymetry, and geophysical data. Create images using Standard, Softened, Wet Look, Shiny Look or Metallic Look colordrape techniques. Select any ER Mapper color table, or various sets of colors for Wet and Shiny looks. Select predefined shade elevations or azimuths, or define your own custom shading. Invert color or shaded image data values if desired, or median filter shaded data to reduce noise. Process a subset of the image area, and specify a wide variety of contrast enhancements. Fine tune all enhancements and options, and immediately see the results.

Color enhancement wizard

Perform several different types of color space enhancements on an RGB image These enhancements are designed to make the image more pleasing to the eye or enhance the overall information content to aid interpretation. Use Hue Saturation Intensity (HSI), Brovey (Chromaticity) Transform, Direct Decorrelation Stretch (DDS), Intensity Convervation DDS, or Hybrid Contrast Stretch enhancement.

Resolution merge wizard

Merge or “fuse” an RGB image with a higher resolution panchromatic image to create a hybrid image with the RGB color and panchromatic spatial resolution. Typical examples are merging Landsat TM 30-meter data with SPOT Panchromatic 10-meter data or SAR imagery. Use Red Green Blue Intensity (RGBI), Hue Saturation Intensity (HSI), Brovey Transform, Smooth Filter Intensity Modulation (SFIM), High Pass Filter (HPF) Additive, or Transparency Merge fusion techniques. RGBI and HSI techniques include histogram matching Pan intensity to RGB intensity, averaging Pan and an infrared band for intensity, and method to convert RGB to Intensity. Process a subset of the image area, and specify a wide variety of contrast enhancements.

SFIM pan sharpening wizard

Use this wizard to pan sharpen a multi-spectral image with a higher resolution panchromatic image. Similar to ‘resolution merge wizard’ but uses different processing logic.

Natural color wizard

Convert typical “false color infrared” images into simulated natural color images, so vegetation appears in green instead of red. Typical data types for this transformation include SPOT XS, Landsat MSS, color infrared (CIR) airphotos, or any data that does not contain a visible blue wavelength band. Use the Simple Weighted Average (WTA) technique to generate natural color, or enhance WTA colors using Direct Decorrelation Stretch (DDS) or Brovey Transform techniques. Generate a vegetation (NDVI) mask to apply the natural color transformation only to vegetated areas, or to modify the transformation effects. Process a subset of the image area, and specify a wide variety of contrast enhancements.

Hope it’s very usefull for you….

Source : ER Mapeer 7.0 User Guide Tutorial