tag:blogger.com,1999:blog-7582438520651320420.post3071099591600176268..comments2019-02-13T10:00:37.422-08:00Comments on Oculus Rift in Action: Understanding the Oculus Rift Distortion ShaderAlex Bentonhttp://www.blogger.com/profile/12907188510267549004noreply@blogger.comBlogger5125tag:blogger.com,1999:blog-7582438520651320420.post-69667863440104507292014-03-20T17:10:24.395-07:002014-03-20T17:10:24.395-07:00It's possible that mathematically speaking, it...It's possible that mathematically speaking, it's not really a barrel distortion, but something more complex. The easiest way to test this would be to apply it to an image over a larger radius and see the behavior of the straight lines in the image. If that's the case then I suspect the use of the term 'barrel distortion' simply refers to the fact that within the constraints of the distortion as used by the Rift (r is never > 1.15) the overall effect is a barrel distortion. <br /><br />However, I'm not really an expert in the area of optics or lenses. I'm mostly trying to make it easier for people to untangle the work required to distort from the work required to move the coordinate from one frame to another. Bradley Austin Davishttps://www.blogger.com/profile/16387001483589908239noreply@blogger.comtag:blogger.com,1999:blog-7582438520651320420.post-19225443297480383742014-03-20T17:05:50.700-07:002014-03-20T17:05:50.700-07:00Good point. I'll try to update the post, and ...Good point. I'll try to update the post, and do a better job of hiding the fact that I haven't worked with OpenGL for about 10 years prior to getting my RiftBradley Austin Davishttps://www.blogger.com/profile/16387001483589908239noreply@blogger.comtag:blogger.com,1999:blog-7582438520651320420.post-16890980146639333502014-03-20T16:55:54.251-07:002014-03-20T16:55:54.251-07:00If this is for a barrel distortion, why expose the...If this is for a barrel distortion, why expose the radial distortion coefficients seperately, when wikipedia says it's a constant among all the coefficients? Is this a case of "good programming" by allowing the program to set those coeffients the same for barrel, and a geometric series for a moustache distortion? I really appreciate you writing this article, it's fantastic. Cheers.TasuLifehttps://www.blogger.com/profile/14925101835846000637noreply@blogger.comtag:blogger.com,1999:blog-7582438520651320420.post-27647368779087374572014-03-05T10:55:31.481-08:002014-03-05T10:55:31.481-08:00Great writeup. One nit-pick:
"If you create ...Great writeup. One nit-pick:<br /><br />"If you create an offscreen buffer with dimensions like 640x800, most likely the underlying texture will be 1024x1024. This means a final scale factor must be applied to the texture coordinates so that the point into the sub-region of the texture memory that's actually populated."<br /><br />This isn't actually the case. It may store the texture at a larger resolution, but accessing pixels will still restrict the texture coordinates to the specified size:<br /><br />https://www.opengl.org/wiki/NPOT_TexturePavelhttps://www.blogger.com/profile/00172351656123377347noreply@blogger.comtag:blogger.com,1999:blog-7582438520651320420.post-85330862195681271202013-12-15T13:46:32.929-08:002013-12-15T13:46:32.929-08:00Thanks for this comprehensive explanation!Thanks for this comprehensive explanation!Anonymousnoreply@blogger.com