The glaciers are melting, that's a sad fact of life.

I'm no big environmentalist, and this won't be one of these "Call to Action" posts. It never occured to me that I could make a difference. I mean, yes, my ride is a scooter with 80 miles/gallon, but that's just because I love my Vespa and I got sick of finding parking in LA ;)

And then there's people like David Breashears. A passionate Mout Everest climber, who made it his lifetime goal to educate people about the climate problem. He's matching famous photographs from a hundred years ago, and it's pretty scary how much the "water towers of the world" have dried out in this time. Check out this video clip:



It's called the Glacial Research Imaging Project (GRIP). You might have seen the New York Times Ad on Synday, on the back cover. More info about GRIP is here and here.

After seeing my 2.5 GPixel Grand Canyon pano, David went back up the mountain to reshoot these pictures in HDR and in really really high resolution. He came to me for some shooting advice. After several phone calls I sort of joined the project, doing the merging, stitching and tonemapping.
An interesting challenge. But well worth the effort, especially when the result turns out like this:


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onmouseout="karakoramthumb.src='http://www.hdrlabs.com/news/files/karakoram_thumb.png'">

David Breashears' Karakoram in 770 Megapixel

You'll get the full explanation to the glacier after Mr. Breashears is back from the mountain, did his round with the scientists, and gets his own website up. I'm just in it for the post processing.

To my knowledge nobody has done an HDR image this big before.

Here's what I learned during the process:

• Photoshop CS4 is the only app that can load and tonemap an EXR file of 6 GB.
• AutoPano Giga can make such a file, but it needs to be on LInear Blending, no Color Correction, and no Compression.
• That's why Vignetting needs to be removed during RAW development (Lightroom here).
• SmartBlend works on PC, but not on Mac. Although it still tends to generate blending artifacts in HDR mode.
• PTGui on the other hand, works great at this size with standard PTGui blending.
• The 64-bit version of CS4 is pretty responsive in the viewport, but every operation (load/save/sharpen/flatten) takes ages. Consdering the image eats up 10 GB of RAM, only my VFX workstation at work can actually do this.
• Tonemapping snow is hard. Somehow it always turns out grey. Figured out that this is just a mental thing: there is no upper point of reference. So there is nothing stopping me from overdoing the local contrasts, effectively working against the overall global contrast and darkening the snow patches.
• TIFF files can't be bigger than 4 GB.
• PSB is the only file format that really works. Can bloat up to > 17 GB, when tonemapping manually with adjustment layers.
• Photomatix 64-bit, made for tonemapping huge images, needs to support PSB. At least the single layer, flattened PSB - otherwise it's kind of pointless.
• Gigapanos are strange. Tonemapping them to look good in every zoom level, all the way out and when focussing on a tiny detail - very hard.

Why did I go full HDR on this?

Using a local tonemapper on the tiles before stitching was my first idea. But that leads to a huge variation in overall brightness. Especially the clear sky tiles turn into a mess, because noise/grain is the only detail emphasized here.

On the other hand, all the snow and ice do show a very high dynamic range. A combined field of view of 320 degree makes it even worse. Compare the result with the Best Exposure Preview stitch, and you'll see that the HDR treatment does make a hell lot of sense. Although, in comparison, that preview stitch was ridicuously easy done in Autopano Giga on MacbookPro.

While my involvement probably won't stop the glaciers, it's nice to gather some Karma points while tackling an interesting HDR challenge like this.