“DAICHI (ALOS)” WITH 3D STEREOSCOPIC SENSOR
The unique characteristic of AW3D technology is using satellite imageries acquired by Advanced Land Observing Satellite "Daichi" (ALOS) of the Japan Aerospace Exploration Agency (JAXA). On DAICHI, an optical instrument, called “Panchromatic Remote-sensing Instrument for Stereo Mapping (PRISM)”, was equipped to generate topographic data with its 3D stereoscopic observation. The sensor consists of three independent panchromatic radiometers for viewing forward, nadir, and backward which means it is capable of acquiring all surface undulations; achieved to represent terrains of complex and steep terrains precisely such as Mt. Everest. Also, an image directly below the satellite (nadir image) makes it possible to generate orthorectified image (true ortho) without any distortion. In addition to this 3D stereoscopic observation, utilizing 3D information (DEM and orthorectified image) added horizontal information makes it possible to identify precise 3D coordinates. Producing this precise 3D coordinate is accomplished by “high accuracy of geolocation position,” which is the advantage of space technology in Japan.
The world’s best satellite technology and high accuracy of geolocation position are the basis of AW3D accuracy.
Japanese satellite “DAICHI (ALOS)” with triplet stereo imageries by nadir, forward, and backward (©JAXA)
Ortho imagery
Imagery corrected its angle to the data plane
Digital Elevation Model (DEM)
A digital expression of the terrain of the ground surface that has digitized height values in intervals of specific lattice points
3D Map
3D map overlaying with ortho imagery and DEM
ADVANCED IMAGE PROCESSING ALGORITHM and HIGH-SPEED IMAGE PROCESSING SYSTEM
Satellite imageries acquired by DAICHI are processed as 3D map with advanced image processing algorithm Remote Sensing Technology Center of Japan (RESTEC) co-developed with JAXA and there are 4 processing stages: preprocessing, 3D analysis, mapping and quality check. There are more than 3 million data images for all gland land spaces acquired by the DAICHI and these number of imageries contain large amount of information. Therefore, processing high resolution imageries requires much more time compared to other lower resolution imageries. The high-speed and high precise information processing technology of NTT Data enables commercialization of product at a realistic timeline. By making further improvements, it is achieved to process 2,000 set (2 terabyte) per day through parallel processing of mass data on the computer server. Nevertheless, it took about 2 years to complete for image processing and verification all over the world. By gathering technologies of Japan in various areas, the world’s first global 3D map with 5m resolution, AW3D, was finally completed.
HOMOGENEOUS ACCURACY CONTROL THROUGHOUT THE WORLD
Evaluation of accuracy performance all global areas were implemented by comparing with using other satellites or ground data. There are more than 4,600 verification points of ground and the current height accuracy (standard deviation) is 3m. This accuracy meets reference value that can be used for land base map such as disaster prevention application.
There are many places in the world where map is not available, however, AW3D is the first 3D map in 5m resolution ever that can be used anywhere in the world. This achievements enable demand correspondence for national/worldwide investigations or simulations for natural resources, environment, disaster prevention, traffic, etc.
Verification result over the entire area: Mean errors within 3.4m
HIGHER PRECISON 3D MAP WITH MULTIPLE SATELLITES
In terms of understanding terrain, 5m resolution is enough to be used. However, it is required detailed undulation information for each building, for example, sunlight simulation for construction plan in urban area. Working with DigitalGlobe, a company located in US, contributed to achieve and respond to such customers’ requirements by utilizing the highest commercial high-resolution earth observation satellites DigitalGlobe owns, called “WorldView” satellites. In this case, technology of producing precise and high-resolution 3D map was developed by combining several satellites equipped with high definition camera and satellites images shot from multiple angles. Thanks to this technology, the accuracy of 3D Map is successfully improved to the level where one tree can be identified.
There are three products are available for AW3D for now: 1) AW3D standard-available entire world DEM in 5m resolution, 2) AW3D enhanced-offering wide range of DEM in 0.5m, 1m and 2m resolution, 3)AW3D 3D building-dataset includes shape and height of buildings and it is available upon request.
DigitalGlobe satellites Constellation (WorldView and others)
Comparison between 5m and 0.5m in urban area. You can recognize building and road much more clearly.
The Diet Building of Japan: Recognizing single tree and its height
COLLABORATION TECHNOLOGIES MAKES CHANGE “MAPS THAT YOU LOOK AT” TO “MAPS THAT YOU CAN USE”
The technology of AW3D has been developed under the concept, from “Map that you look at” to “Map that you can use.” Up until now, AW3D was developed as a “useful” global 3D map in 5m resolution at low cost by gathering satellite technology of JAXA, data analysis technology of RESTEC and information-processing technology of NTT Data. Furthermore, high-resolution satellite imageries of DigitalGlobe made it provide “more useful” 3D Map.
Currently, technological development of AW3D has been driven to focus on providing more value-added information as a part of total solution which links the customer’s business applications. Developing and providing the 3D map that can be practically used for customers’ operations leads to success of customers’ business, for example, providing flood disaster in real-time integrated to the global observation change system or wind-power plant integrated to the wind analysis software.
These collaboration technologies were custom-made at this moment, however, it has been working on developing to commercialize a product by utilizing technical know-how it’s been accumulated.
Signal propagation simulation using propagation modeling application