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UGEIP Project

Project Title   Universal Geometry Engine Preparation
Project Acronym   UGEIP
Contractor(s)   INDRA Espacio (Spain), Institut de Geomàtica (Spain)

 

Project     Context
             Objectives
            Architecture
    How it Works
 

  


Context

Within EO context one of the main issues to be solved prior to the effective use of products imaging the Earth surface is to locate them with reference to the scene being observed. Another common need of EO products is to geometrically relate them with each other.

  • Application projects where EO imagery is used usually imply multi-source data integration: images and cartography (raster-vector), or fusion of images (raster-raster) are just examples. 
  • Correction of geometric distortions are outstanding for these kind of activities to allow for element comparison, registration and overlay. The impact of distortions are becoming a more important problem with very high resolution satellites.

From the geometric point of view, both issues mentioned above can be stated in the same manner: how to relate or transform known source coordinates to unknown destination coordinates. This relation can be represented as a geometric sensor model.

In such a transformation several matters are involved: knowledge of the platform position at every instant during the image acquisition, of the particular sensor configuration, of the type of scene being imaged and the particular scene, of the state of the atmosphere at that moment. 

The Universal Geometry Engine is to be a system able to perform the estimation (in a least squares adjustment sense) of a geometric model for a given set of entries, where the model is a function that relates source coordinates with destination coordinates (image coordinates with terrain coordinates), and the entries are a specific configuration of the imaging system or systems and a set of reference data.

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Objectives

UGEIP project is a preparatory phase for the development of a Universal Geometry Engine whose aim is to provide to the EO user with the means needed to ensure a coherent geometry among a set of images, each one acquired by a given sensor, so that they can be jointly processed.

The main objective of this phase project is to prepare the design documentation needed for the future development of a system able to compute the required geometric model parameters of a set of images acquired by any of a wide variety of sensors so that heterogeneous EO imagery can be exploited in a consistent way.

The objectives of UGEI system, from functional point of view, are to:

  • Extract information from auxiliary satellite/aircraft image product files on:
    • Exterior orientation (orbit, attitude)
    • Internal orientation (sensor geometric configuration)
  • Provide the user with the capability to generate observation data: Ground Control Points and Tie Points
  • Perform the estimation of a geometric model parameters based on previously identified input data
  • Provide the user with exploitation applications of adjusted model parameters such as: orthoimage production through a generic orthoimage engine, monoplotting and stereoplotting, sensor calibration (geometric, radiometric, simultaneous sensor, assimilation of other data or other models – meteorological / atmospheric …), simulation of sensor performance for sensor design and optimisation, simulation of sensor performance for optimal mission design, multisensor co-registration for further data fusion and interpretation, monosensor co-registration for temporal analysis, orbit adjustment.

Main and innnovative design aspects of the system are the combination of the following features:

  • The extension of the geodetic/photogrammetric network methodology and its underlying mathematical theory to remote sensing
  • The use of a sensor geometric rigorous model representing the physical reality of the image acquisition geometry. These models account for the effects of the platform (position, velocity and attitude), the sensor (viewing angles), the Earth shape and the relief, so that the influence of each of the parameters can be physically interpreted. Sensor models of different types shall be implemented in UGEI: ERS PRI, SPOT-5 and airborne frame camera.
  • Ability to handle and adjust several sensor models types simultaneously i.e: SAR and optic
  • Extensibility: incorporation of new sensor models or observation types will not impact on system architecture. Sensor models shall be encapsulated in cartridges with an standardized interface.
  • Genericity: each and every model to be internally treated in the same way,
  • Deployment
    • desktop
    • selected components will be prepared to be deployed in network environment
    • processing components shall provide an API facilitating its use from an external application

 

Benefits expected upon achievement of functional and design objectives are:

  • Reduction of dependence on external tools 
  • User knowledge and control of the modeling (capability to act on model parameters)
  • Identification of some repetitive patterns in sensor modeling
  • An universal geometry modelling approach with standardised modeling concepts

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Architecture

The UGEI main components are the following

 

  • Ingestion of orbit, attitude and sensor calibration data from product image either from satellite or airborne sensors.
  • Observation generation: ground control points and tie points.
  • Numerical core able to perform optimal estimation of model parameters.

 

The output from UGEI will be used by the Orthoimage Generation application: based on the estimated model parameters and a DTM, produces an orthoimage in a cartographic system selected by the user.

UGEI system architecture has a 4-tier architecture as the one shown in the following figure:

Image

 

The role of each layer is the following:

  • The upper layer, control layer, implements the mechanism for the execution of algorithms developed in the computation layer.
  • The GUI layer implements the interface to the user.
  • Computation layer offers an API to the upper layer and encapsulates the mathematical algorithms.
  • Libraries layer contains a set of shared libraries used by upper layer components.

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How it Works

The figure below depicts the main processes and data-flow within UGEI . Also included is an application of UGEI output: the orthoimage generation application.

Image

Sequence of operations sketched in the diagram can be summarized as follows:

  1. Product image of a vendor of a adequate level is ingested in the system, that means:
    1. Conversion of image data to tiff format
    2. Manual input of orbit, attitude (EOP) and sensor calibration (IOP) by operator or retrieval from product auxiliary image data and transformation to internal UGEI format
  2. Operator using an appropriate GUI locates GCP and TP over images, those data are stored for ulterior processing
  3. Data gathered in step 1 and 2 are input to Network adjustment that perform an optimal estimation in the least square sense of EOP and/or IOP parameters
  4. Using adjusted parameters computed previously and a DTM an orthoimage is generated

     

The Final Presentation was held at ESRIN on October 15, 2004.


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