PDA

View Full Version : Creating HDRi images from panoramas


Snake Eyess
11-16-2012, 08:15 AM
Is it possible to generate HDRI files for lighting/reflection from standard panoramas, with a few shots taken looking slightly more up?
i.e. no fish eye lens or reflective chrome sphere

CHRiTTeR
11-16-2012, 01:26 PM
You'll need to take shots at different exposures to compute the dynamic range etc

Snake Eyess
11-16-2012, 02:07 PM
I know about the different exposures, which I have... just wanting to know if you can actually generate the HDRI using a standard lens, I.E. no fish eye lens

pokoy
11-16-2012, 02:36 PM
Yes, possible. If it's for a 360 deg panorama, you'll need a lot of shots depending on the focal length of the lens. With a 18 mm fisheye you'll need around 8-10 shots, with 24 mm you'll need some more shots to cover the whole 360 degrees.

If it's only for a photo of a lamp or something, yes, also possible.

PTGui is an excellent program to stitch whatever you have and export that as exr or hdr.

Snake Eyess
11-16-2012, 02:43 PM
i think im going to need more shots then :(

its for a live action/3d comp for reflections mainly, but if i can get a basic lighting out of it, it will help

pokoy
11-16-2012, 04:45 PM
You should be able to figure out the field of view of the lens in combination with your camera's sensor. This would give you a number of how many shots you need (360 degrees / horizontal resp. vertical fov). Then add around 20% or 30% overlap for the stitching software, just multiply the number of the horizontal/vertical shots by 1.2-1.3.

For lighting, make sure you have enough EV steps in the bracketing (exposures) so you really capture all the light information.

The good thing about the greater focal length is you get quite a high resolution panorama, but it takes longer to process and - depending on the resolution of the camera - it's a lot of data to tackle. Also, consider that it takes longer to shoot it, so if you're in a fast moving environment (for example clouds or a city with moving cars etc.), you'll probably need to retouch the final panorama file.

...or consider renting a fisheye lens!

Panupat
11-16-2012, 04:55 PM
If basic lighting is all you want, a chrome sphere HDR will be a ton simpler.

MisterS
11-16-2012, 11:59 PM
I use a regular 10mm lens, and it works great, you can use any lens you want. I tend to shoot 8 bracketed sets on a single row for photography purposes. You'll need more rows or a wider lens for HDRIs for lighting.

Check this out: http://www.hdrlabs.com/tools/panocalc.html

obviously the longer the lens, the more photos, storage, processing and time is involved.

PTGui is the best stitching app I've tried.

Nodal Ninja make good cheap (compared with other brands) pano heads.

CGTalk Moderation
11-16-2012, 11:59 PM
This thread has been automatically closed as it remained inactive for 12 months. If you wish to continue the discussion, please create a new thread in the appropriate forum.