Hi Zhe, I¹m glad you brought this up and thank you Greg for the clarification.
Best Regards Raquel Raquel Viula PhD Researcher TU Delft | Faculty of Architecture and the Built Environment | Architectural Engineering and Technology Julianalaan 134, 2628 BL Delft, The Netherlands | P.O. Box 5043 2600 GA Delf From: Zhe Kong <[email protected]> Reply-To: High Dynamic Range Imaging <[email protected]> Date: Saturday 28 January 2017 02:09 To: <[email protected]> Subject: Re: [HDRI] Convert equisolidangular to equiangular projection Sorry about the confusion I brought up. I got this wrong information from the manufacturer. If I recall my previous experience, Sigma f/3.5 matches Radiance -vta pretty well. The current mismatch might be caused by the camera coordinate in the simulation. Anyway, Happy Chinese New Year, everyone! Zhe On Fri, Jan 27, 2017 at 10:11 AM, <[email protected]> wrote: > Send HDRI mailing list submissions to > [email protected] > > To subscribe or unsubscribe via the World Wide Web, visit > http://www.radiance-online.org/mailman/listinfo/hdri > or, via email, send a message with subject or body 'help' to > [email protected] > > You can reach the person managing the list at > [email protected] > > When replying, please edit your Subject line so it is more specific > than "Re: Contents of HDRI digest..." > > > Today's Topics: > > 1. Re: Convert equisolidangular to equiangular projection > (Gregory J. Ward) > > > ---------------------------------------------------------------------- > > Message: 1 > Date: Fri, 27 Jan 2017 08:10:53 -0800 > From: "Gregory J. Ward" <[email protected]> > To: High Dynamic Range Imaging <[email protected]> > Subject: Re: [HDRI] Convert equisolidangular to equiangular projection > Message-ID: <[email protected]> > Content-Type: text/plain; charset="windows-1252" > > Raquel points out an important error in this discussion's terminology. The > "equidistant" fisheye does indeed correspond to the "-vta" view type in > Radiance. However, the "-vth" type corresponds to a hemispherical projection, > which very few commercial fisheye lenses realize. In particular, the > equisolidangle projection is much closer to "-vta" than it is to "-vth". If > your lens is equisolidangle, then you need to use the fisheye_corr.cal script > or similar to convert it to an equidistant projection. > > I have not implemented the equisolidangle projection, though there is a third > fisheye type (-vts) which is called "stereographic", although we prefer the > term "planisphere" projection to avoid confusion with stereo views. This does > not correspond to any commercial lenses to my knowledge, but I'd be interested > to hear of one. > >> > From: Raquel Viula <[email protected]> >> > Date: January 27, 2017 5:49:57 AM PST >> > >> > Hi all, >> > Thank you for raising this topic and sharing your views. I?m using the >> output of a Sigma f=4.5mm F/2.8 for several analysis including DGP via >> Evalglare that should require a -vth or -vta view, so this is critical >> information for me. >> > May I ask why people refer to -vth as equi-solid angle and not >> hemispherical as it is defined in Radiance?s rpict man page? >> > My understanding from that page and from Axel Jacobs' presentation sent via >> the link just before is that there isn't a Radiance description for the >> equi-solid angle view. >> > >> > Best Regards >> > >> > Raquel Viula >> > PhD Researcher >> > >> > TU Delft | Faculty of Architecture and the Built Environment | >> > Architectural Engineering and Technology >> > Julianalaan 134, 2628 BL Delft, The Netherlands | P.O. Box 5043 2600 GA >> Delft >> > >> > From: Claus Br?ndgaard Madsen <[email protected]> >> > Reply-To: High Dynamic Range Imaging <[email protected]> >> > Date: Friday 27 January 2017 13:49 >> > To: High Dynamic Range Imaging <[email protected]> >> > Subject: Re: [HDRI] Convert equisolidangular to equiangular projection >> > >> > >> > >> > Hi everyone, >> > >> > Some years ago I tested my Sigma 8mm lens, f3.5. >> > >> > At the time I found several sources online claiming it to be equi-solid >> angle (-vth), but it didn?t match my personal experiences with the lens, so I >> tested it. >> > >> > My tests showed it to be equidistant (-vta), i.e. identical to the angular >> fish eye projection in RADIANCE. >> > >> > So, in my experience, the 8mm Sigma lens is equidistant. >> > >> > Cheers, >> > Claus >> > >> > >> > >> > Claus B. Madsen >> > Assoc. Prof., Ph.D. | Department of Architecture and Media Technology >> > >> > Phone: +45 9940 8788 <tel:%2B45%209940%208788> | E-mail: >> > [email protected] >> > Aalborg University | Rendsburggade 14 | 9000 Aalborg | Denmark >> > >> > Employee No.: 107255 | Vat No.: DK29102384 >> > >> > >> > From: "J. Alstan Jakubiec" <[email protected]> >> > Reply-To: High Dynamic Range Imaging <[email protected]> >> > Date: Friday, 27 January 2017 at 11.33 >> > To: "[email protected]" <[email protected]> >> > Subject: Re: [HDRI] Convert equisolidangular to equiangular projection >> > >> > A little followup that is worth noting is that Axel Jacobs measured the >> Sigma 4.5mm and found it to have an equi-solid angle projection. See his >> presentation here: >> https://www.radiance-online.org/community/workshops/2012-copenhagen/Day2/Jaco >> bs/Jacobs-AJ09-HDR_Radiance_WS-2012.pdf >> > >> > Alstan >> > >> > >> > On 1/27/2017 6:26 PM, J. Alstan Jakubiec wrote: >> > Hi Tobias, >> > >> > I just purchased a pair of Sigma 8mm f/3.5's for my work, but I haven't >> measured them for vignetting and angular verification yet. It is on my to do >> list :). I will be disappointed if they are equi-solid angular however. Will >> let you know sometime after the Lunar new year. >> > >> > Alstan >> > >> > >> > On 1/27/2017 6:17 PM, Tobias Porsch wrote: >> > Hi Alstan, >> > >> > I'm not sure if your below description is correct. >> > In my experience it's exactly the opposite. The Sigma f=8mm F/3.5 lens is >> an equi-solid angle (-vth) and the Sigma f=4.5mm F/2.8 is an equi-distant >> (-angular) (-vta) lens. >> > Can you please double-check that issue for me? >> > >> > Cheers >> > Tobias >> > >> > Von: J. Alstan Jakubiec [mailto:[email protected]] >> > Gesendet: Donnerstag, 26. Januar 2017 06:58 >> > An: [email protected] >> > Betreff: Re: [HDRI] Convert equisolidangular to equiangular projection >> > >> > Hi Zhe, >> > >> > As far as I am aware, the Sigma 8mm f/3.5 is an equi-angular (-vta) lens, >> and the Sigma 4.5mm f/2.8 is an equi-solid angle (-???) lens. I am having >> trouble finding a source from Sigma right now, but Cauwerts, Bodart and >> Deneyer's paper says so. >> > >> > That said, if you do end up with an equi-solidangle image, I have a python >> script that converts equi-solid angle to equi-angle for each source jpeg >> while maintaining the EXIF data. I used this to convert equi-solidangle >> images from my Canon 8-15mm fisheye lenses. >> > >> > Best, >> > Alstan >> > >> > On 1/26/2017 8:48 AM, Gregory J. Ward wrote: >> > Hi Zhe, >> > >> > You should be able to apply the fisheye_corr.cal file I gave you earlier to >> correct the distortion and make it an angular fisheye image that pinterp >> works with. (Why you need pinterp, I am not sure.) The command is as >> suggested in the fisheye_corr.cal file itself: >> > >> > pcomb -f fisheye_corr.cal -o fisheye.hdr \ >> > | getinfo -a "VIEW= -vta -vh 180 -vv 180" \ >>> > > corrected.hdr >> > >> > This will also crop the area outside of 180? to black, assuming that is >> what you want. It assumes that you have already cropped the image to a >> minimum square area. You should apply vignetting correction and absolute >> calibration first. >> > >> > Cheers, >> > -Greg >> > >> > From: Zhe Kong <[email protected]> >> > Date: January 25, 2017 1:15:49 PM PST >> > >> > Dear list: >> > I am trying to compare HDR images and simulated luminance maps. Since I use >> SIGMA 8mm 1:3.5 for Canon, I need to convert equisolid-angular to equiangular >> project. I see very useful information from the post below: >> > >> > >> https://www.radiance-online.org:447/pipermail/radiance-general/2015-August/01 >> 1184.html >> > >> > However, I still have some questions need to figure out. >> > 1) pinterp does not include equisolid-angular projection, so a equation >> needs to be applied to the function. Greg mentioned this simple expression, >> sin(theta)/theta, but I am still confused. Could anyone offer me the command? >> > >> > 2) The post discussed the steps of processing HDR images. If I get it >> right, the steps following "adjust exposure" are vignetting correction, >> adding view information, converting project from equisolidangular to >> equiangular, then calibrating the image. I use a GOSSEN Starlite 2 to record >> the luminance value on a grey card for calibration. My question is, should I >> calibrate the image before or after converting fisheye projection? >> > >> > Any suggestions or explanation would be appreciated. >> > Zhe >> > >> > >> > _______________________________________________ >> > HDRI mailing list >> > [email protected] >> > http://www.radiance-online.org/mailman/listinfo/hdri >> > >> > >> > >> > >> > _______________________________________________ >> > HDRI mailing list >> > [email protected] >> > http://www.radiance-online.org/mailman/listinfo/hdri >> > >> > >> > >> > >> > _______________________________________________ >> > HDRI mailing list >> > [email protected] >> > http://www.radiance-online.org/mailman/listinfo/hdri >> > >> > >> > _______________________________________________ HDRI mailing list >> [email protected] http://www.radiance-online.org/mailman/listinfo/hdri >> _______________________________________________ >> > HDRI mailing list >> > [email protected] >> > http://www.radiance-online.org/mailman/listinfo/hdri > -------------- next part -------------- > An HTML attachment was scrubbed... > URL: > <http://www.radiance-online.org/pipermail/hdri/attachments/20170127/f2bd1701/a > ttachment.html> > > ------------------------------ > > Subject: Digest Footer > > _______________________________________________ > HDRI mailing list > [email protected] > http://www.radiance-online.org/mailman/listinfo/hdri > > > ------------------------------ > > End of HDRI Digest, Vol 87, Issue 6 > *********************************** -- Zhe Kong PhD Student University of Wisconsin - Milwaukee School of Architecture and Urban Planning 2131 E. 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