DSW700 System Description
time variable dark frame captures to determine a set of bias and gain adjustments. These adjustments are measured for every pixel in each color band to correct for variations in radiometric response over the entire sensor area, as well as discrepancies in time of exposure. The bias and gain adjustments are then saved in calibration files for later application to the image patches captured during digitization.
5.Photo/stage orientation (interior orientation) This function is used to establish a precise photo-to-stage coordinate transformation (interior orientation) for the input film placed on the digitizer stage. The transformation is based on the measurement of up to eight fiducial marks. It provides for transformations from a simple scale and rotation to a standard affine fit. The program assists the operator in the location of the fiducial marks, automatically slewing to their approximate positions. Real-time light control and zooming of the image is available to assist the operator in pointing (measuring a sub-pixel location). The user can easily store the coordinates of the fiducial marks with the other camera calibration data. When the fiducial marks on the first image from a particular camera are measured, their image patches are stored as templates to enable automated interior orientation of subsequent images acquired by the same sensor, essential for autonomous operation with roll film. In addition, fiducial marks can be specifically enhanced in the scan without disturbing the geometric placement. This allows scans to be made with highly readable fiducial marks.
6.Image scanning Image scanning, sometimes called image digitizing, and utilizes the CCD sensor to convert the image transparency into digital data for use on digital photogrammetric workstations. A large capacity hard drive is provided as standard equipment for archiving of scanned imagery. Other output devices can be provided. In standard configurations where the DSW700 is an element of a larger system, imagery can be transferred electronically over a local network, in which case GigaBit connection with Category 6 cabling is strongly recommended. Several image formats are supported, both on-the-fly and off-line, including plain raster (Band Interleaved by Line), VITec, TIFF, tiled TIFF, tiled TIFF JPEG, NITF JPEG and JPEG2000. An embedded set of minification levels may be optionally stored in the tiled TIFF formats and JPEG2000.
7.Supporting software In addition to the applications described above, the software package includes a number of utilities which can be used to accomplish a variety of common tasks. This set of command line utilities are most commonly applied to: reformat scanned imagery into any of the common raster formats mentioned above; have the final resolution of a digitized image re-sampled to any coarser final resolution; and convert color images to black and white, or have the final radiometric characteristics of the image modified after data collection. Additionally, since all of the utilities are executed from a command line, they may be embedded in a script or batch file to modify a large number of images at once. A powerful viewing program is also included to check the appearance of the completely scanned image.
