If memory serves me, it is his paper from the Dallas 2005 convention. Yep, it is. Here is a PDF of his slides. And here is the link from shroud.com, which reads, “Evidence that the Shroud was not Completely Flat during the Image Formation” which, now, nicely redirects to the copy at Academia.edu (nicely done).
IT’S A MUST READ. So if you have not done so or you need to refresh your memory, read it now.
The abstract reads:
We show that, when the images formed, the frontal part of the Shroud of Turin laid on a body in the same position as when the blood stains formed by contact. In other words, after the Shroud was laid on top of a body, no forceful flattening occurred before the images formed. Moreover, the argument that the top half of the Shroud could not have been draping a real body when the images formed – to avoid prominent image distortions – is shown to be incorrect. If a cloth is appropriately laid on the front part of a body, and a body image forms by a vertical projection on the cloth, no major image distortions occur. Small image distortions are to be expected, and indeed we can observe some on the Shroud. These two aspects – the Shroud was not forcefully flattened before the images formed and no major image distortions occur due to the way the Shroud was laid on the body – give the simplest scenario for the formation of the images. There is no need to claim a special event that would have flattened the Shroud before the images formed. Our analysis is based on precise length measurements on digital images, the blood stain locations, and geometry.
And why you must carefully read this paper; this is from the conclusion
. . . We have also conjectured that the mechanism of projection is probably neither normal to the skin, nor to the sheet, and not really perpendicular to gravity, but is probably following the shortest path to the sheet. Further research is necessary to conclude on this aspect.