The WorldView-2 satellite is equipped with the most advanced control moment gyro, and is the first high-resolution 8-band multi-spectral satellite for commercial use. Like the WorldView-1 satellite, the WorldView-2 satellite is highly agile, has rapid targeting, and is able to carry out efficient in-track stereo collection. As it has a higher orbital altitude than the WorldView-1 satellite, it also has a shorter revisit time. The WorldView-2 satellite is able to collect 50 cm-resolution panchromatic images and 2.0 m-resolution 8-band multi-spectral images within a 975,000 km2 area in one day.
This section provides an introduction to product levels based on differences in correcting methods for positional accuracy, and production options based on differences in image processing levels. Based on differences in the correction methods for product level positional accuracy, we provide nine types of images; "Basic Imagery," "Standard Imagery (two types)," and "Orthorectified Imagery (six types)."
Basic Imagery: Images targeted at customers who are able to undertake an advanced degree of image processing
Only radiometric correction and sensor correction are carried out.
Standard Imagery: Images targeted at general customers
In addition to radiometric correction and sensor correction, geometric correction is also carried out for distortions arising as a result of the earth's spherical surface. Furthermore, with regard to reference ellipsoid, images are corrected applying coarse DEM in order to normalize for topographic relief.
Ortho Ready Standard Images are targeted at customers who wish to carry out orthorectification on their own. These images are provided alongside the RPC information needed in the correction process. Please refer to the product guide for details.
Orthorectified Imagery: Images targeted at customers using images for GIS application and the creation of maps
In addition to radiometric correction, sensor correction, and geometric correction, terrain correction is also carried out using DEM and GCP. As mapping is made onto a map projection plane, these images can be used to detect changes and for other analytical applications that require a high level of absolute precision.
Types of Orders
Orders may be made for all satellites; QuickBird, WorldView-1, and WorldView-2.
Select Tasking is positioned as an entry-level ordering format for orders of new acquisition or collected images.
Orders are accepted for the shooting period requested by customers (maximum of 365 days).
Feasibility studies for acquisitions are carried out, and the customer is informed of the probability of conducting successful acquisition during the collection windows specified by the customer.
New collection or imaging orders for basic stereo pair images for the WorldView-1 satellite can only be ordered under the Select Tasking program (specified collection windows must be more than 90 days).
■Select Plus Tasking
Orders may be made for all satellites; QuickBird, WorldView-1, and WorldView-2.
Select Plus Tasking provides a higher level of service than Select Tasking. As a result of feasibility studies, Select Plus Tasking customers are provided with a shorter collection windows than Select Tasking customers for regions that we receive many acquisition orders.
Orders are accepted for the collection windows requested by customers (maximum of 365 days).
Feasibility studies for acquisitions are carried out, and the customer is informed of the probability of conducting successful acquisitions during the collection windows specified by the customer.
Orders may be made for QuickBird and WorldView-2 satellites.
DigitalGlobe (Hitachi Solutions) exerts the greatest effort into ensuring successful acquisitions during the collection windows for Assured Tasking orders.
During the collection windows agreed upon before the order is placed, DigitalGlobe (Hitachi Solutions) puts its best effort into providing the satellite capability that is necessary for success in Assured Tasking.
Customers may specify the shooting period (maximum of 365 days).
Feasibility studies for acquisitions are carried out, and DigitalGlobe (Hitachi Solutions) provides customers with a recommended collection windows.
In the case that the customer decides to place an order through Assured Tasking, the customer will be required to agree to this recommended collection windows (it may not necessarily be possible to agree to the collection windows that the customer requests for).
In the event that all acquisitions/imaging cannot be conducted successfully during the collection windows (for example, when weather conditions are extremely poor, or when unforeseen circumstances arise), customers will be asked to select one of the following options:
1. To extend the collection windows. A new collection window to continue acquiring for the areas that were not acquired successfully will be proposed to the customer.
2. To terminate the acquisition. However, customers must purchase the images that were successfully acquired or imaged.
Points to Note when Purchasing Images
WorldView-2 satellite images may only be used upon the customers' agreement to the "DigitalGlobe Product End-User License Agreement." Please read the contents of the agreement carefully prior to your purchase.
All products and derivative products must clearly show the following copyright notices.
Products: "©DigitalGlobe, Inc., All Rights Reserved."
Derivative products: "Includes copyrighted material of DigitalGlobe, Inc., All Rights Reserved."
Characteristics of WorldView-2
8-band multispectral sensor
WorldView-2 satellite is equipped with high-resolution 8-band multispectral sensor that has four new bands (Coastal, Yellow, Red Edge, and NIR2) in addition to the four bands (Blue, Green, Red, NIR1) in the QuickBird satellite.
Characteristics of the new four bands
■Coastal (400 to 450 nm)
This band supports vegetation identification and analysis based upon its chlorophyll absorption characteristics. As it has a high degree of water penetration attribute, it can be applied to bathymetry surveys for depth, monitoring of coastal regions, and analyses of coral reefs. In addition, as it is susceptible to the impact of atmospheric scattering, it is also used in investigating atmospheric correction techniques.
■Yellow (585 to 625 nm)
This band is used to specify the "spectral characteristics of yellow" for land features, which is important in the analysis of water turbidity and vegetation applications. It is also used to create true-color hue correction that look natural to the human eye.
■RedEdge (705 to 745 nm)
It can be applied to stress analysis for vegetation.
■NIR2 (860 to 1,040 nm)
It provides a clear distinction between vegetation and non-vegetation, and supports broader vegetation analysis and biomass studies.
Efficacy of 8-band analysis: Enhances accuracy of land cover classification
Classification accuracy = 47.3%
Classification accuracy = 76.5%
Land cover classification based on 8-band images enables detailed classification that was difficult to achieve with conventional 4-band images.
The following figure shows the land cover classification results for 11 items using QuickBird and WorldView-2 simulation images. This example demonstrates an improvement in accuracy of approximately 30% for an 8-band analysis as compared to a 4-band analysis.
Efficacy of 8-band analysis: Enhances color reproducibility
The case of WorldView-2 satellite
Using 8-band information from the WorldView-2 satellite improves color reproducibility. The figure on the right shows a simulation example.
Each cell in the following figure shows the actual color in the upper portion and the reproduced color using each satellite sensor in the lower portion. From this figure, it is clear that the WorldView-2 satellite can reproduce the actual colors.
*Display on a computer may be dependent upon the software used.
The WorldView-2 satellite has approximately five times the acquisition capability of the QuickBird satellite.
If operation of the WorldView-2 satellite commences under the current double-satellite operation, the daily acquisition capability would be 1,910,000 km2 (approximately five times that of Japan's total land area). With that, we can expect an expansion in the scope of development for image archives and improvements in the frequency of image updates.
Enhancement of image archive line-up
With a three-satellite system in combination with QuickBird and WorldView-1, daily collection capability would improve significantly, resulting in the further enhancement of our image archive line-up.
WorldView-2 Satellite Specifications
|Launched||October 8, 2009|
|Pixel resolution||Panchromatic||0.46 m (Nadir)|
|Multispectral||1.84 m (Nadir)|
|Onboard sensors||Panchromatic: 450 to 800 nm
Coastal: 400 to 450 nm
Blue: 450 to 510 nm
Green: 510 to 580 nm
Yellow: 585 to 625 nm
Red: 630 to 690 nm
RedEdge: 705 to 745 nm
Near-infrared 1: 770 to 895 nm
Near-infrared 2: 860 to 1,040 nm
(Within 30º off-Nadir)
|1.1 days (resolution below 1 m) 3.7 days (52 cm resolution)|
|Swath width||16.4 km (Nadir)|
|Max contiguous area collected
(in a single pass)
|Normal imaging: 96 km x 110 km
Stereo imaging: 48 km x 110 km
|Geolocation accuracy||Precision Horizontal error: 6.5 m (CE90%)*|
|Overpass time||10:30 a.m.|
|Launch vehicle Lauching rocket||Boeing Delta II|
|Launch site||Vandenberg Air Force Base, California, United States|
|Orbit altitude||770 km (Sun-synchronous orbit)|
|Orbit period||100 minutes|
*excluding terrain and off-nadir effects