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PTViewer is a well-know panorama viewer running as a Java applet and powering many of the 360-degree panoramas showed on the web.
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With version 3.1 released in December 2003, PTViewer can now display High Dynamic Range panoramas as well. It works with input files in the Radiance RGBE format (.hdr) or in the Floating Point JPEG format (.fjpg). The Floating Point JPEG format has been actually developed for the purpose of PTViewer -- it is a highly compressed version of the Radiance format, intended to drastically reduce the size of the input file and thus make it suitable for interactive viewing of 360° panoramas on the web. |
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The FJPEG compression is thus very useful but it comes at a price though -- in many cases, JPEG artifacts are visible in some parts of the panorama, especially in the highlights when the bright zone is small compared to surrounding darker zones. A higher compression factor reduces the artifacts but increases the file size as well. |
We are showing two examples of HDR panoramas viewed in PTViewer 3.1. To produce the FJPEG files read by the viewer, we did the following:
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Shooting each angle of view of the panoramic scene under different exposure levels (those levels being fixed values, i.e. the same for all views). |
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Stitching images of the same exposure level into a panorama. This gave us as many panoramas as exposure levels. |
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Processing the differently exposed panoramas in Photomatix to create an HDR panorama and save it in the Radiance RGBE format (.hdr). |
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Converting the Radiance file produced into a Floating Point JPEG file with PTConvert. We used the PTConvertInterface utility for this. |
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Example 1: Château de Flaugergues (800 KB) |
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Example 2: Viaduc de Millau (488 KB) |
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