The Keystone Image Management System archives, catalogues and processes digital images from satellites and airborne digital sensors. All types of geospatial imagery can be stored in the Keystone Server allowing both overview and full-resolution data to rapidly be accessed using web-based interfaces.

The Keystone System minimises manual intervention in the image supply process and significantly shortens image delivery times. Rigorous photogrammetric techniques ensure high accuracy results while allowing users to interact with the system in a geographically oriented, map-based view.

The Keystone Server is built using open source technologies and Open GIS standards. This makes it the ideal solution to incorporate into an existing environment. GIS-ready products can be generated in any of the approximately 3,000 supported geodetic coordinate systems, while access to the Keystone Server is straightforward using standards-based clients such as World Wind and Google Earth. Imagery can be browsed online at up to its full resolution with on-the-fly geocorrection providing exactly the view the user wants to see. This enhances data access to support near real-time information delivery for applications such as security and disaster mitigation.

The Keystone concept is based on more than 20 years of experience in satellite image processing system development. It adds a new dimension of automation to proven methodologies, resulting in the highest possible accuracy and speed. The Keystone System is a generic platform for geospatial image management which makes both standard and customised capabilities easy and quick to put in place. Standard solutions include support for Spot, Landsat, Ikonos, QuickBird and Worldview, while custom systems have been provided for a range of customers. The high level of automation makes it possible to manage very large datasets with a minimum of manual interaction.

A proven solution

Cataloguing

The European Space Agency (ESA) is using the Keystone Server to generate on-the-fly browse image maps from their catalogues and archives of over 300,000 satellite images. With the Keystone System, ESA is generating orthorectified browse images from more than 20 satellite sensors. Users can request image maps using the WMS standard to access image maps from almost any GIS.

Archiving and product processing

Several members of the Disaster Monitoring Constellation of satellites are using the Keystone System to provide integrated archiving, cataloguing and product processing solutions. Each of the satellites has been characterised with a unique sensor model, making it possible to achieve accuracy of less than half a pixel in the image products. The DMC Keystone Systems can receive product orders, initiate product processing and deliver automatically to end users. There are installations in the UK, Spain and Nigeria.

Rapid access

Spacemetric has provided a number of Keystone Image Management Systems to the Swedish Air Force for use with the SAAB Gripen's SPK39 reconnaissance pod. This Keystone system installations will manage large volumes of classified, high-resolution imagery in a time-critical application. They support priority-steered download of imagery and a customised sensor model for accurate geolocation of the imagery using aircraft attitude and position data. As a multi-sensor platform the Keystone System will also manage satellite imagery and other imagery sources to provide geographical context and situational awareness.

Architecture

The Keystone System architecture enables easy integration into existing infrastructure. It has been designed to manage high workloads of diverse image material where there is a need to be able to scale the system with growing demand.

Sensor modelling

The sensor model is used in creating an image's geometrical model. The Keystone Server offers a library of rigorous sensor models, which together with the image metadata and attitude and orbital models allow an analytical relationship to be established between the raw image pixels and the Earth coordinate system. This rigorous physical approach provides the highest geometrical accuracy while allowing new or changed sensor configurations to be added easily.

Catalogue and archive

The image catalogue is optimised for fast search and browse and consists of a database of all image metadata and quick-looks. Meanwhile, the image archive contains full-resolution scenes with all images are stored in their original coordinate system. Coordinate transformations are performed on demand. The Keystone System data model contains original image metadata and the derived geometrical model for an image with multiple image model versions supported.

Automatic accuracy refinement

The Keystone System supports advanced refinement of image accuracy using precision geometric modelling. Automated matching to existing reference material enables updates to be made to the image geometrical model. The final geometrical accuracy achieved is limited by the quality of the reference material while the process itself is capable of sub-pixel geolocation accuracy. Multiple versions of the image model are saved within the Keystone Server.

Automatic workflow management

The Keystone System's workflow management is the heart of the overall process automation. Workflow management keeps track of customers, areas of interest, product orders, and product processing specifications. It includes a notification system for new images and for finished products that are available for download.

Catalogue search and browse

Standards-based search and browse services can accessed through the Keystone Web Portal, the Keystone Console, or any WMS client. Other integration options are also available through the Keystone System APIs.

Ortho on-the-fly

All image rectification is carried out on the fly where images are resampled to the chosen coordinate system for fast access on screen. Through a search users can select single images, parts of an image, or a set of images that are then orthorectified to the screen. On-the-fly rectification makes use of parallel processing techniques and supports rapid access to imagery. This is of value in security-related applications where a short turnaround time from acquisition and the ability to combine with other geospatial datasets are crucial.

Keystone Console

The Keystone Console provides access to all Keystone System functionality in a single, easy-to-use client application. It supports image and metadata search and browse, output product design and online delivery. It also offers advanced tools for update of image geometry using reference datasets to source ground control.

Product generation

Image products are rectified and mosaiced on demand. Products can be single scenes or be made from parts of many images to cover an arbitrary area. This means that users can easily visualise and obtain products that are not constrained by scene or other boundaries such as map sheets.

Google Earth and World Wind

The Keystone System supports open standards such as WMS making it easy to integrate into existing infrastructures and clients such as World Wind and Google Earth.

GIS

Most commercial GIS systems can access data on the Keystone system using OGC standards. Keystone offers a high degree of flexibility by allowing the GIS user to select from more than 3,000 predefined coordinate systems or to define their own system. The Keystone system’s mosaicing capability gives a direct overview of archived images as a GIS layer.