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submission_guidelines [2017/03/02 10:02] – [Reflectance Transformation Imaging (RTI)] lafontsubmission_guidelines [2017/04/29 15:09] (current) englund
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 <box 320px right>{{:guidelines_scan_r_te_copy.jpg?300|Fig. 3, Workflow after reverse}}</box|Fig. 3, Workflow after reverse> <box 320px right>{{:guidelines_scan_r_te_copy.jpg?300|Fig. 3, Workflow after reverse}}</box|Fig. 3, Workflow after reverse>
  
-(8) Edges are difficult to scan due to the fact that tablets do not naturally rest on their edges and a tablet that is standing on its edge could be damaged if it falls over onto the surface of the scanner. So it is always best to prop up a tablet on its edge by some means available to you. Ideally, the supporting props employed should be black in color with a matte finish. These black props then disappear or can more easily be erased when producing the archival "fat cross" representation of tablets chosen by the CDLI ([[http://cdli.ucla.edu/dl/photo/P005478.jpg|example]]). Under no circumstances, however, should a colored or textured background be allows to stand above the tablet so as to appear in the background of the tablet image (fig. 4).{{ :guidelines_scan_te.jpg?250|Fig. 4, Scanning the top edge with support}}+(8) Edges are difficult to scan due to the fact that tablets do not naturally rest on their edges and a tablet that is standing on its edge could be damaged if it falls over onto the surface of the scanner. So it is always best to prop up a tablet on its edge by some means available to you. Ideally, the supporting props employed should be black in color with a matte finish. These black props then disappear or can more easily be erased when producing the archival "fatcross" representation of tablets chosen by the CDLI ([[http://cdli.ucla.edu/dl/photo/P005478.jpg|example]]). Under no circumstances, however, should a colored or textured background be allows to stand above the tablet so as to appear in the background of the tablet image (fig. 4).{{ :guidelines_scan_te.jpg?250|Fig. 4, Scanning the top edge with support}}
  
 (9) Keep your eyes on the surface of the scanner to detect the accumulation of dust and fingerprints (as noted above, careful placement of a tablet on the surface of the scanner often requires touching the surface of the scanner with the fingertips, so expect to clean up a lot of fingerprint smudges). Clear any tablets or props off the surface of the scanner, blow any dust or other particles off the surface and clean off any remaining fingerprints or smudges with a piece of lint-free cloth. (9) Keep your eyes on the surface of the scanner to detect the accumulation of dust and fingerprints (as noted above, careful placement of a tablet on the surface of the scanner often requires touching the surface of the scanner with the fingertips, so expect to clean up a lot of fingerprint smudges). Clear any tablets or props off the surface of the scanner, blow any dust or other particles off the surface and clean off any remaining fingerprints or smudges with a piece of lint-free cloth.
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 CDLI requires that its archival images be in a 24 bit RGB format (hence 8-bit channel), even if the image is black and white.  CDLI requires that its archival images be in a 24 bit RGB format (hence 8-bit channel), even if the image is black and white. 
  
-=== Generating a fat cross in Adobe Photoshop ===+=== Generating a fatcross in Adobe Photoshop ===
  
 The following workflow describes step-by-step, how to create the final representation of a tablet in the CDLI database based on images produced by a flatbed scanner.  The following workflow describes step-by-step, how to create the final representation of a tablet in the CDLI database based on images produced by a flatbed scanner. 
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 When preparing files for upload and backup, it is important to note that the above file-structure should be used for each side of the captured object. In order to avoid the usage of too much storage-space the content of "jpeg-exports" should be deleted before upload.  When preparing files for upload and backup, it is important to note that the above file-structure should be used for each side of the captured object. In order to avoid the usage of too much storage-space the content of "jpeg-exports" should be deleted before upload. 
  
-=== Processing RTI captures === 
  
-There are several ways to process images taken by the camera dome to an output file (*.ptm)The easiest way is to use the "builder"Upon opening there appears a small window. By pressing on the button "Build" the respective face of a captured artefact needs to be chosen. The user needs to select the main folder itself and not its sub-directories. Depending on the computer memory the processing takes about 2-5 minutes, whose completion is indicated by a dialogue "Fitting completed". In contrast to the RTIbuilder offered by Cultural Heritage Imaging, the fitting software takes all necessary steps itself. It copies the images in the directory "original-captures" and creates a duplicate in "jpeg-exports". After that the ptm-fitter is used in combination with the coordinates of each light source saved in "generic.lp". The 76 light positions (lp) represent the coordinates on the X, Y, and Z axes and are derived from the original calibration of the camera dome[This calibration is done by placing a glossy ball (e.g., a red or black snooker ball) in the dome reflecting the various lights. Due to the reflections on the glossy sphere the location of the light source within the hemispheric camera dome can be extrapolated. A similar approach is achieved using highlight RTI and therefore an ever changing set of light positions within each capture.During the building process the lp-file is copied into the folder "assembly-files" and renamed: capture.lp. +[[http://cdli.ucla.edu/pubs/cdln/php/single.php?id=54|Here are information on capturing RTI images with the camera dome]]\\ 
 +[[http://cdli.ucla.edu/?q=rti-images|Here are samples of RTI images of cuneiform texts and cylinder seals]]\\
  
 +=== Processing RTI captures ===
  
-[[http://cdli.ucla.edu/pubs/cdln/php/single.php?id=54|Here are information on capturing RTI images with the camera dome]]\\ +There are several ways to process images taken by the camera dome to an output file (*.ptm)The easiest way is to use the "builder"Upon opening there appears a small window. By pressing on the button "Build" the respective face of a captured artefact needs to be chosen. The user needs to select the main folder itself and not its sub-directories. Depending on the computer memory the processing takes about 2-5 minutes, whose completion is indicated by a dialogue "Fitting completed". In contrast to the RTIbuilder offered by Cultural Heritage Imaging, the fitting software takes all necessary steps itself. It copies the images in the directory "original-captures" and creates a duplicate in "jpeg-exports". After that the ptm-fitter is used in combination with the coordinates of each light source saved in "generic.lp". The 76 light positions (lp) represent the coordinates on the X, Y, and Z axes and are derived from the original calibration of the camera dome[This calibration is done by placing a glossy ball (e.g., a red or black snooker ball) in the dome reflecting the various lights. Due to the reflections on the glossy sphere the location of the light source within the hemispheric camera dome can be extrapolated. A similar approach is achieved using highlight RTI and therefore an ever changing set of light positions within each capture.During the building process the lp-file is copied into the folder "assembly-files" and renamed: capture.lp. 
-[[http://cdli.ucla.edu/?q=rti-images|Here are samples of RTI images of cuneiform texts and cylinder seals prepared]]\\+
  
 === Processing RTI images for webviewer === === Processing RTI images for webviewer ===
submission_guidelines.1488448937.txt.gz · Last modified: 2017/03/02 10:02 by lafont
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