Orthorectification that corrects the perspective distortion of remote sensing imagery, providing accurate geolocation and
ease of correlation to other images is a valuable first-step in image processing for information extraction. However, the
large amount of metadata and the floating-point matrix transformations required to operate on each pixel make this a
computation and I/O (Input/Output) intensive process. As result much imagery is either left unprocessed or loses timesensitive
value in the long processing cycle.
However, the computation on each pixel can be reduced substantially by using computational results of the neighboring
pixels and accelerated by special pipelined hardware architecture in one to two orders of magnitude. A specialized
coprocessor that is implemented inside an FPGA (Field Programmable Gate Array) chip and surrounded by vendorsupported
hardware IP (Intellectual Property) shares the computation workload with CPU through PCI-Express
interface. The ultimate speed of one pixel per clock (125 MHz) is achieved by the pipelined systolic array architecture.
The optimal partition between software and hardware, the timing profile among image I/O and computation, and the
highly automated GUI (Graphical User Interface) that fully exploits this speed increase to maximize overall image
production throughput will also be discussed. The software that runs on a workstation with the acceleration hardware
orthorectifies 16 Megapixels per second, which is 16 times faster than without the hardware. It turns the production time
from months to days. A real-life successful story of an imaging satellite company that adopted such workstations for
their orthorectified imagery production will be presented. The potential candidacy of the image processing computation
that can be accelerated more efficiently by the same approach will also be analyzed.
The benefits of remote sensed imagery cannot be fully exploited without displaying the images in real-time. This paper
describes a viewer system that displays orthorectified images in several modes and will allow accurate geo-location
information, change or motion detection and offers situation awareness in real-time. And, through the use of a real-time
viewer the image acquisition platform can be interactively redirected to focus on objects or location of interest to
improve overall reconnaissance efficiency.
High speed orthorectification is an enabling technology which can shorten the delay between image acquisition and precise geolocation to almost zero. This paper describes recent advances in orthorectification processing speeds and shows how the speeds now possible can permit image fusion, change and motion detection, ground control collection and adjustment to be done in real time. It also shows how orthorectification can provide an alternative means of video compression.
Geolocation error in aerial imagery can arise from many sources. This paper catalogs the major sources and shows how residual error may be reduced still further through the use of ground control points.
For many years the demand to record both instrumentation and reconnaissance data was satisfied by high-end ruggedized digital tape recorders, notably the Ampex DCRsi. In recent years other technologies such as solid state and disk have entered the market. These technologies overcome the sequential access limitation of tape (albeit at a significantly higher data storage cost) which could be a benefit depending on the application and implementation. This paper describes the key differences between instrumentation and reconnaissance (imagery) recording and shows: • That instrumentation recording is inherently a sequential process itself,• That current disk and solid state recorders are yet limited by what is in effect a sequential interface.• That imagery recording could benefit substantially from random access, but only after enhancing the interface, and • That an image logger (herein defined) provide a superior method for recording imagery.
Change detection and motion detection is theoretically possible using image fusion--imagery of a common area from multiple sensor platforms. However perspective differences represent a significant obstacle both to human and machine correlation, particularly in the case of side oblique imagery. Orthorectification provides a common perspective and thus a practical first step for follow-on correlation algorithms.
Today's modern image processing software that removes pointing angle and platform anomalies through the photogrammetric orthorectification process offers some utility that if mitigated to hardware could provide near real-time on platform or on sensor capability. The orthorectification process, however, is so computation intensive and time consuming that real time operation is generally not available.
This paper describes a low-cost means of performing real-time orthorectification, a brief overview of the orthorectification process and how it relates to targeting and location measurement. Also included in the presentation is a dynamic demonstration of two commercial software packages being used to extra geocoordinate information from a high resolution digital image.
Even though film is often thought to be a dinosaur in modern airborne acquisition systems it is still unsurpassed in capability to provide the most resolution and detail to the analyst who is chartered to extract the highest level of intelligence possible. The inability to quickly provide information from acquired film imagery has been one reason stated by field commanders as to their preference for "all digital" camera systems. Digitally scanning the film and adding modern digital processing to scanned images would enhance the "data mining" of archived imagery and could also maintain the exceptional quality of image data from today's film systems. New software developments, if applied, could also shorted the time line betwen the acquisition and the user.
Draping an aerial photograph over known elevation data enables simulated views of the same area from an arbitrary point of view. Doing this in software for a high resolution image could take days. Commercial hardware is available to do this in hours. This paper will present a method for doing it in seconds. Similarly, comparing two images of the same target which have been taken from different altitudes or directions requires one or both images undergo perspective correction. Perspective correction is a computation intensive process made even more complex when the images cover mountainous terrain. This paper will describe hardware that can in real time eliminate the perspective difference between two such images.