Ashmolean Museum, Processing: 10 (2023-07-22)

Created by: Wagensonner, Klaus

Using dome captures (I)

Much work is being done on developing an online RTI-viewer, which allows to adjust the light angles in a web-based environment (see, for instance, the Portable Light Dome). In the meantime captures taken by the camera dome can be used to gain a good 2D-result. It must be stressed that this process cannot be automatised. Each side need to be treated individually. The end result sometimes may seem over-edited, but it is aimed at provided the most readable result. After processing the raw files to a PTM file, this file is opened in a locally installed RTI-viewer (see earlier posts). Depending on the curvature of the object either three or four images with different light angles need to be exported. On the left-hand side three such exported shots of Ashm 1922-176 are shown with indication of the various light sources (yellow points on green). Image 1 uses light from the upper left corner, Image 2 from the lower left corner and Image 3 from the right side. (1) In a first step all three shots are opened in Photoshop. First, Image 2 is copied onto Image 1. Since on Image 2 the light comes from the lowerleft corner, we can select the areas of better visibility. (2) The selection needs to be feathered in order to avoid sharp borders and have a smooth transition between the different images. That being done the selection is copied into a new layer. The original Image 2 can now be removed. In some cases one of the layers needs some adjustments. Of course, parts of Image 3 still need to be blended over this result. This will be shown in tomorrow's post.

credit: Wagensonner, Klaus