Ok, so perhaps I've found a Hugin bug. The EV's I posted earlier were auto calculated by Hugin when I added my JPEGs to the project. I just selected them all now and did a reset in the camera tab (selecting only to reset the EXIF values), and now they are all properly (consistently) calculated. When I get some free time, I'll see if I can reproduce it.
My calculations now all match Hugin's with two exceptions: 1.) Hugin is definitely not making any corrections for ISO Speed. 2.) Hugin is using (or assuming) more accurate values for the Shutter Speed. Where EXIFTOOL rounds 0.3s, Hugin is using 1/3s. Oh, and I did find where EXIF is calculating LV which it refers to as EV with ISO Speed accounted for (see #1 above). But it is pretty imprecise as it seems to use rounded values for shutter speed (one decimal place) and then rounds the final value too (one decimal place). Hugin's is much more accurate. So my only questions are: * Is Hugin somehow getting EXIFTOOL to output more precise values (like 0.333333s vs 0.3) or is Hugin just making its own assumptions? * Should Hugin be calculating EV taking ISO speed into account? -Chris On Feb 1, 10:37 am, Chris Parrish <chris.parr...@swankinnovations.com> wrote: > Actually, it looks like Hugin is not compensating for ISO Speed. The > values that it's using are more like: > ( 2*log($aperture) - log($et) ) / log(2) > > I'm not sure if that's a bug in Hugin or intentional. > > And I can't find any documentation that shows that EXIFTOOL calculates > EV at all. Does/can it? > > It also appears that Hugin is converting shutter speed values such as > "1.3" to more precise values such as "1 + 1/3" (unless there's some > way to get EXIFTOOL to output more precise values that I've never > figured out). Do you have any insight here? > > But where I'm really confused is that I have a project with different > JPEG files -- all with the same exposure settings (each is the third > shot of a bracketed set and the EXIF info shows each to have: ISO=400, > Aperture=18.0, Shutter Speed=1.3). But, for some reason, Hugin > calculates different EV's for each: > Image 1: Eev7.96133843254863 > Image 2: Eev8.22471080582863 > Image 3: Eev8.01714501898585 > Image 4: Eev7.92977368023845 > Image 5: Eev7.92771999334261 > Image 6: Eev7.91554178809828 > Image 7: Eev7.9863593751747 > Image 8: Eev7.94803346282545 > Image 9: Eev7.87540508845236 > > Even more strange, Hugin calculates the EV's consistently for the 1st > and 2nd shots in the bracketed sets (all the 1st shots get exactly the > same Eev as do all the 2nd shots). It's just this 3rd set of image > that have this weird variation. > > Is there some other weird factor that Hugin is using to calculate EV > that I'm not accounting for? Or is there a high-precision mode to use > to get data via EXIFTOOL? > > -Chris > > On Feb 1, 2:11 am, "bruno.postle" <brunopos...@googlemail.com> wrote: > > > On Feb 1, 6:28 am, Chris Parrish <chris.parr...@swankinnovations.com> > > wrote: > > > > I am building a script that batch creates PTO and PTO.MK files for > > > sets of pano images. I do this based on templates of these files (I > > > use a pano head allowing me to reuse the same script settings in these > > > templates). > > > > The problem is that, while I can keep the lens and transform settings, > > > I do need to change the Eev value to match the actual images' exposure > > > values. I can get all the data using EXIFTOOL but when I calculate > > > the EV I don't get what Hugin is getting. > > > > Does anyone know Hugin's actual formula? > > > EV (light value) is fairly standard, Hugin should be doing it the same > > as exiftool (and does as far as I know). > > > It's a log scale where a value of 0.0 is defined as f/1.0 at 1.0 > > second with ISO 100), this is how it is calculated: > > > (2*log ($aperture) - log($et) - log($iso/100)) / log(2) > > > -- > > Bruno -- You received this message because you are subscribed to the Google Groups "hugin and other free panoramic software" group. A list of frequently asked questions is available at: http://wiki.panotools.org/Hugin_FAQ To post to this group, send email to hugin-ptx@googlegroups.com To unsubscribe from this group, send email to hugin-ptx+unsubscr...@googlegroups.com For more options, visit this group at http://groups.google.com/group/hugin-ptx
