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View Full Version : how do I MAKE an HDRI map?


wasbubs
09-10-2008, 04:41 AM
I've seen lots of tutorials about how to use hdri maps in 3d, but how do I actually go about making one?

from what I gather it involves taking a picture of a silver shiny ball at different exposures, combining them, ???, then you have your HDRI map. For some reason I think there may be more to it than that...

That about right? does anyone have any sites they've seen about this? I've seen some tutorials on how to make HDR images for Photography to make your images brighter or more surreal. I'm assuming its a similar process but with a round silver ball...

Call me crazy but I think making the maps sounds fun. I like to take pictures of stuff and want to use my camera to benefit my 3D. And yes it is a DSLR, but I heard you could also do it with a P&S if you can change the shutter speed.

So. Any tips?

JamesMcPhail
09-10-2008, 04:49 AM
HDR Shop has a pretty good intro.

http://projects.ict.usc.edu/graphics/HDRShop/

You can also use Merge to HDR in photoshop.

Tlock
09-10-2008, 04:00 PM
For a more affordable solution yet with full capabilities of Photoshop, you could consider at least trying out Artizen HDR.

Michael32766
09-10-2008, 11:12 PM
Here is a tutorial using PTGUI to combine the images to make an HDRI.
http://www.ptgui.com/hdrtutorial.html

Also Try getting this book
http://www.hdrlabs.com/book/index.html
Check through that web site for more info.

I think in the next issue of HDRI magazine there will be a small tutorial I wrote on shooting HDRI's with a Cannon camera and a Fisheye lens and using PTGUi to combine the images.

Hope that helps some,
Michael

wasbubs
09-11-2008, 01:42 AM
Cool thanks. I'll give the these a look!

On a side note for some reason cgtalk quit emailing me when I get a response to a message... Even though I subscribe to the thread AND select instant email notification on the dropdown menu...

anyone know why? just curious...

niva
09-11-2008, 01:55 AM
This is because CG talk haters u! Maybe your email changed or is old? Check your profile settings.

Actually I'm interested in this topic too. What is the actual technique used to capture the HDRI images and piece them properly into one seamless HDRI?

lostpencil
09-11-2008, 02:47 PM
I found this useful: http://www.cambridgeincolour.com/tutorials/high-dynamic-range.htm

P_T
09-11-2008, 03:02 PM
If you have some extra cash and haven't done so already, why not invest on a circular fisheye lens like Sigma 8mm (or 4.5mm if you have a camera with APS-C sensor). No need to carry around a mirror/chrome ball that might get scratched or break, one less thing to go wrong.

wasbubs
09-11-2008, 03:51 PM
that lens looks a tad bit pricey for me at the moment... but that sounds like a way easier thing to do than get a ball and a way to hold the ball up.

does it work? have anyone hear made hdri maps with a circular fisheye lens?

imashination
09-11-2008, 04:33 PM
It depends what you want to do. A fish eye lens will not give a good reflection/illumination map; unless you want to just shoot skies with clouds, shooting a mirror ball is really the only sensibly priced option. It doesnt have to be huge, heavy or perfect. Ive gotten extremely good results from a christmas tree bauble and a piece of blutack to keep it stuck on top of a wall, branch, fence etc.

P_T
09-11-2008, 04:48 PM
It depends what you want to do. A fish eye lens will not give a good reflection/illumination map;Why is that?

This guy seem to be doing alright with it.
I get some very clean 4000x2000 panos out of the Sigma 4.5 and the D200.
Artifacts are higher than on the Nikon 10.5, but with careful preprocessing this is not a problem. Here is my current workflow:

- shoot RAW, 9 frames in 1 EV intervals
- develop in Lightroom: all settings zeroed, linear tone curve, white balanced, and correct chromatic aberration(!!!)
- stitch and merge in PTGui in one step
- finish in Photoshop CS3 (clone stamp out little lensflares, cover up nadir point)

All together takes about 30 minutes. Got some good practice lately while making a massive amount of HDRIs on set. The Sigma 4.5 is perfect for this, because I can run into the fully lit set and do the shoot in 20 to 30 seconds. So the AD doesn't hesitate to leave the lights up after the take is wrapped, even when the shooting schedule gets tight. More chances, more locations, and a relaxed atmosphere on set are worth the lower resolution. 4000x2000 is still good enough for reflection and lighting map, even background in D1 resolution. Only falls apart in HD size. Wish I could show you some panos from my latest shoot, but we had a special briefing about the classified nature of it.... But I am in the middle of preparing a movie tutorial about the entire process for Siggraph.
http://www.hdrlabs.com/cgi-bin/forum/YaBB.pl?num=1205108073

imashination
09-11-2008, 06:09 PM
Why is that?

This guy seem to be doing alright with it.

http://www.hdrlabs.com/cgi-bin/forum/YaBB.pl?num=1205108073

Because a fisheye lens doesnt cover everything, basically. To do a 360 horizontally, you need to take 3 sets of the standard 7 shots. Even if you manage to stitch all 21 shots together, youre still either missing the top of the hdri or the bottom.

Michael32766
09-11-2008, 07:52 PM
Hi, the one thing that most people don't know is if your going to shoot with a fish eye lens you need to use a special tripod head called a nodal head.

http://www.nodalninja.com/
This allows the lens to be rotated around the nodal point of the lens and allows the images to be stitched together easier.
This also allows you to also get a large image that has high details, no fringing or out of focus areas on the sides.
So the work flow with a Fish eye lens is this:
Tripod with nodal mount for camera
Fish eye lens
Method of shooting multiple frames at different exposure levels.
Either manually adjusting the exposure or with a camera remote control, or with the camera hooked to a laptop.
http://www.breezesys.com/

Then point the camera North, shoot 9 bracketed exposures
Rotated the the camera 90 degrees: East, shoot 9 bracketed exposures
Rotated the the camera 90 degrees: South, shoot 9 bracketed exposures
Rotated the the camera 90 degrees: West, shoot 9 bracketed exposures
Point the camera up, Sky, shoot 9 bracketed exposures
Point the camera down, Ground, shoot 9 bracketed exposures
The Ground shot can be a bit tricky depending on your tripod.

Next create a single individual HDRI image for each direction using
Photmantix
http://www.hdrsoft.com/index.html

Load the 6 HDRIs into PTGUI to stitch them together and output a single HDRI Dome image that can be used in your 3d program.
http://www.ptgui.com/hdrtutorial.html

You can also load all the raw images in PTGui and skip using Photomantix.
I didn't do this at first because PTGUI did would not load the raw files from my Camera.
I use a sigma 4.5 Fish eye lens and a Cannon 40D with a nodal Ninja mount and it all works fine.


There are other ways of doing this but this is the easiest way I have found yet.

thanks,

Michael

wasbubs
09-11-2008, 09:27 PM
cool good info.

the fish eye lens looks awesome but I think I'll stick to the Ball until I get used to making HDRI's and get enough money for a fish eye lens...

but This is good info! I'm definitely gonna get out there and take some pics next time the weather permits, and I have the time.

mushroomgod
09-11-2008, 10:07 PM
Because a fisheye lens doesnt cover everything, basically. To do a 360 horizontally, you need to take 3 sets of the standard 7 shots. Even if you manage to stitch all 21 shots together, youre still either missing the top of the hdri or the bottom.

well, you can always take 8x3 shots then and cover the fill 360. But 7x3 is fine, just angle the fisheye up slightly (5 degrees) and it will cover everything apart from whats directly under the camera (no different than a mirror ball...presumably thats on a stick or something?), and that area is very very easy to fix in photoshop.

Or, buy a fullframe camera and then you could cover the full 360 in 3x3 shots.

Iv used Mirror balls in the past, I wouldnt touch them again, the fisheye setup is a million times better - in resolotion, information captued, its like comparing A6 to A3 as far as quality goes.

PTGUI, is also very good at stitching many images together to build a HDRI, iv stitched 50+ images together no problem......took an age though :)

But it is pretty costly, I would estimate my setup - camera, fisheye, tripod, software, panohead, comes in at around 1000-1300.


A mirror ball setup is a good 50% less, but then again the qualitys a good 50% less too.

P_T
09-12-2008, 01:20 AM
Or, buy a fullframe camera and then you could cover the full 360 in 3x3 shots.That's why I mentioned Sigma 4.5mm circular fisheye which was designed for APS-C sensor.

See this is why I suggested a Photography subforum but it looks like Photography's getting no love here which is surprising considering how closely related it is to CG. The fact that Suggestion forum is all the way at the bottom where hardly anyone visit doesn't help either.

Please visit and vote if you like photography and see the how beneficial it is for 3D.
http://forums.cgsociety.org/showthread.php?f=155&t=659723

wasbubs
09-12-2008, 02:42 AM
thats actually a good idea P_T

I'm going to try some shots this weekend. with the ball. photo is just hobby for me that I thought could benefit my 3D. I may well get a circular fish eye in the future but fore now its out of my student budget.

it would be cool to have a photo sub forum so i can post my results! or at least an HDRI section...

Blochi
09-28-2008, 10:38 PM
well, there is always the forum at www.hdrlabs.com/forum , where you can post your HDRIs and also get help from other panoramic HDR photographers.

I'm the author of the HDRI Handbook (www.hdri-handbook.com), and there is a rather large tutorial section on mirror balls, fisheyes, gear, nodal point, all that good stuff. If you're primarily interested in mirror ball photography, there is also a pretty good beginners tutorial here: www.hdrlabs.com/siggraph ... the same mirror ball tut in the book goes a little further, though, by shooting and combining 2 angles into one HDR pano with better quality.

cheers,
Blochi

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