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DPChallenge Forums >> Hardware and Software >> Gigapixel Panorama Speedtest
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 04/02/2009 12:23:41 PM · #1
For those interested in doing stitched panoramas but don't know how practical it is on your own system then this test is for you:
Gigapixel Panorama Speedtest

This is an extreme stress test for your system to find out just how good it is for processing large photo images, how it will perform and what limitations you will encounter.

I was inspired to do this test on my new computer by kirbic who last October performed a similar test on his, then new, Vista 64-bit computer system and described it in this DPC discussion:
Vista 64, first impressions

I'll explain later, but the test has some real world limitations... but first some testing info and results.

Test Description:
The panorama stress test consists of stitching 337 individual images using PTGui panorama software. Each image is 6 megapixel .jpg files schrunk to files ranging in size from 115Kb to 296Kb each. Total size of all the files is about 68.6 megs.

The test creator provides a specially prepared project file with all the control points and other configuration and setup already done. You, the user, simply build the panorama from the project file as is. That is the test.

I do not own PTGui so I downloaded and installed an evaluation copy called "PTGui Pro 8.1.4 trial for 64-bit Windows".
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My System Configuration:
Windows Vista Home Premium 64-bit
8 Gigs RAM
4 X 1 terabyte HD drives in a RAID-10 array configuration (meaning it is both striped and mirrored for 2 terabytes total storage)
AMD Anthlon 7750 dual-core processor at 2.7Ghz on a Foxconn Digitalife A79A-S motherboard
ATI Radeon X1950 Series graphics adapter for two DVI monitor connections
2 X 24" display monitors, each 1920 X 1200 native screen resolution, in an extended 1 and 2 monitor configuration
Photoshop CS4 Extended 64-bit
Lightroom II 64-bit

I wanted a good test to put this system through it's paces and this test seemed ideal for that. I was also interested in how my results compared to kirbic's test on his Windows system.
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Tests and results:
My intention was to simulate how I'd do panoramas in a real world situation. For a variety of reasons I normally build and store all images in .tif format, so I did it that way here as well.

I conducted a number of speedtest runs but there were really only two that mattered.

1-Open project file... no changes... click "Create Panorama" button
Load: 3:00 minutes (I allowed all 337 thumbnails displays to show before doing anything else)
Align: 4:45 minutes
Create: 4:20 minutes
Total Time: 12:05 minutes

File density: 8468 X 2390 pixels
File size: 24 Megabytes
Print size at 300dpi: 27.9" X 8"

That is lightning fast until you notice a couple things. The image was curved, not flat, and the entire stitch of 337 images is only 24 megabytes. For a panorama that is microscopic and the final result was... welll... wrong! :) . Heck, the native image size of a single out-of-camera image file from my camera is 21 megabytes.

I don't know why the panorama was so tiny but undoubtedly because panorama stitching is finicky and I didn't do something I should have. I don't know what that might have been now.

2-Open project file... make output file as large as possible... click "Create Panorama" button
This is where Windows limitations show up. This time I probably followed procedures better including an optimization thing that resulted in a clean, rectilinear image.

Total Time: 1 hour 4 minutes (the "save" part of the total time was under 2 minutes)

File density: 65,000 X 13,981 pixels
File size: 1.46 Gigabytes
Print size at 300dpi: 216.6" X 46.6" (That is about 18 feet by 4 feet... which is pretty big)

Now THAT is more like it, but still not the full size the image wants to be. It actually wants to be something like 81,000 X 20,000 pixels.

3-File Size limitations:
The reason it isn't full sized is because PTGui tries to build a .tif file larger than 4 Gigabytes. 4 Gigs is the largest file size allowed by PTGui AND Photoshop CS4 and I think it is a file format size limitation. There is no other photo file format that allows a larger file size and most of the others have a 2 gigabyte file size limitation.

So, I limited my pixel size output to 65,000 X 13981 after experimentation found that 70,000 was still too big but 65,000 was not. LOL!!!!

Of course, I could simply have output to .jpg and would have got the whole panorama at the maximum size and it would have made no difference in the final image quality since the inputs were .jpg anyway, but that is not how I want to work in the real world so I did not take that option.
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Working with Stitched Panoramas in Photoshop CS4
Shelving the idea of using CS4 to build panoramas for the moment; I wanted to see how peppy or sluggish PS CS4 64-bit was on my system when working with large stitched panorama files. After all, if every operation takes a zillion years then you aren't going to do much with panoramas anyway.

So I opened the 1.46 Gigabyte file in CS4 and began a couple simple things like I might do to a "real" image. First thing I always do is convert my images to 16-bit, so I did that. Then, for a simplistic test, I duplicated the BG layer twice. I applied 'Auto Tone' to one layer and 'Auto Contrast' to the other.

Overall, CS4 was a bit sluggish but quite workable. I could stretch the image across to fill both 24" monitors and it is a bit slow to render the image the first time it's on screen but after that you can pretty much move around, zoom in and out, and scroll to your heart's content with hardly skipping a beat. That is nice!

Btw... panoramas stretched across TWO 24" monitors are AWESOME!!! Can't imagine what 30" ones would be like.

Then I saved the file... :(

I maxed out with the two layers I created. The output file saved with just 3 layers is a whopping 4.23 Gigabytes AND I had to save it zip compressed to make it small enough. The save probably took 35 minutes or so. That was disappointing, I was hoping it would be much faster. Then, at the very end of the save I got this awful message saying the max file size for .tiff is 4 Gigs and it had been exceeded and suggested saving to a different format.

I gasped... but when I looked the file was indeed created. I opened the 3 layer panorama file (which took several minute) that I'd just created and went over it with a fine toothed comb and there did not appear to be any file corruption. It is just fine.

I figure I hit so close to the theoretical file size limitation that CS4 got confused so sent the message even though the save was good.
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Conclusions
Kirbic's test took an hour and 20 minutes or so and my second test took an hour and 4 minutes. But it isn't an apple to apples comparison. I suspect kirbic saved his at full pixel density but as a compressed .jpg file. Mine was at a lower density but as an uncompressed .tif file. His final panorama was 2.4 Gigs while mine was only 1.5 Gigs. I'm sure those choices affected our respective panorama builds ruining them for direct comparative purposes.

Whereas I was able to squeeze 3 layers out in a file in PS CS4 I doubt kirbic's file could even hold a second layer... every change would have to be flattened into a single layer before the file could be saved. Like me, Kirbic would have to make quality control decisions working with his file is he wanted to do much with it at all.

Though this is by far the largest number of images I've ever stitched there are some aspects of this test that are contrived just for testing purposes that don't apply to the real world.

First and foremost, the 377 images are tiny, TINY little low res .jpg input files. Though each is 6 megapixels they are only about 1/10th their native size. They have been shrunk considerably. It sticks out like a giant sore thumb when the image is viewed at 100% resolution, particularly in the sky.

At their native recorded size Windows Vista 64-bit and all my software could never stitch this file at its full resolution because it would far, far, far exceed the theoretical maximum allowed file size of 4 Gigs even if you picked .jpg so could never capture it at it's full resolution. The best you could do was reduce the size of the output file until it finally dropped below the theoretical max.

That defeats one of the main purposes of making a panorama in the first place!

As mentioned earlier. The size of all 377 images is only 68 Megs which is barely over 3 times the size of ONE of my cameras native output files. That means I'm severely limited in the number of images I can use in a panorama without giving up all that great data I paid so dearly for from camera. :(

I will have to verify this, but to me it looks like 3 full sized images is about all I'll be able to stitch before cutting quality corners. I find that very disappointing.

I don't know how things are in the Mac world, but in the Windows world as I know it no one can create and store high density, high quality image data. It is impossible.
 04/02/2009 05:42:58 PM · #2
Originally posted by Artifacts:
I don't know how things are in the Mac world, but in the Windows world as I know it no one can create and store high density, high quality image data. It is impossible.

So I guess a 13 Gigapixel pano is impossible, like this one //www.harlem-13-gigapixels.com/ ?

A .psb can exceed 4GB, its limits are 300,000 pixels in each direction. Then use a PS plugin to break the image up into smaller tiles for Zoomify or HDView. And there are other solutions.

Message edited by author 2009-04-02 17:43:26.
 04/03/2009 03:48:53 PM · #3
You are correct... saying it is "impossible" is incorrect... but that isn't what I said... what I said is that it is impossible "in the Windows world as I know it". That part is correct for me or any Windows Vista Home Premium 64-bit user. I don't know what, if any, limitations there might be on the Mac but it obviously can be done in Linux.

It is a fantastic panorama!

It is a 279,689 X 46,901 pixel photo image created on a 64-bit Linux OS system and took 46 hours to render. It was done using Autopano Pro Linux version on a "special" though relatively modest sounding hardware setup.

Btw, by comparison, the image I tried rendering with PTGui was "only" about 81,000 X 20,000 pixels which is well within .psb limits. I could build the whole .psb file in PTGui but I could not save it! It exceeded the 4 Gig barrier. That is the part making it impossible in Vista 64.

Since there isn't a Linux version of Photoshop CS4 or Lightroom II then I'd have no way to post process a big file like that even if I made one. LOL!!!!
 04/03/2009 08:15:45 PM · #4
Hey Steve,
Good to see your results posted... yes, I did run my test to JPEG output, so that I could create the full-size panorama. I'd never stitch to JPEG of course, in real life, though ;-)
Your comments on the file size limitations are I think correct, and with the size of 16-bit images out of the 5DII (or even the 5D for that matter) it really wouldn't take all that many images to reach it... I can tell you, though, that I haven't bumped into it... yet!
 04/03/2009 08:21:18 PM · #5
Steve,
How are your drives partitioned? Are they partitioned as NTFS? The 4GB file size limit applies only to FAT32 format; the NTFS file system supports file sizes of up to 16TB minus 64kB, per this page

Message edited by author 2009-04-03 20:26:28.
 04/05/2009 04:30:03 PM · #6
Originally posted by kirbic:
Steve,
How are your drives partitioned? Are they partitioned as NTFS? The 4GB file size limit applies only to FAT32 format; the NTFS file system supports file sizes of up to 16TB minus 64kB, per this page

I have 4 individual 1 terabyte drives for a total of 4 terabytes of disk storage. All 4 drives are the same manufacturer and all 4 are formatted NTFS.

They are setup in a RAID-10 array to give 2 terabytes of addressable memory. The array is mirrored and striped. The RAID array is partitioned into two logical drives. One is a 100 Gig system drive that has the operating system and all the applications... the other is a data drive.
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Limits reached??

I do NOT think you were able to render the full sized image in .jpg. The reason is simple. At the default 75% quality setting, the image is simply too big. Besides that, PTGui returns a message saying it cannot build a .jpg larger than 25K pixels wide. The full size of the image is around 81,000 X 18,000 pixels which is much wider. I read somewhere the max pixel density allowed by .jpg is 64,000 X 64,000 pixels. That produces a 4 gigapixel image which is not theoretically wide enough for that 81,000 pixel wide panorama that can be stitched by PTGui. I think I also saw somewhere that 2 gigabytes is the maximum file size allowed for a .jpg file in Windows, even 64-bit.

I believe I rendered close to the theoretical maximum retaining any sort of quality in a Windows Vista environment. I built it as a .tiff because that is one of the few formats that allows an image that large. The other two are .raw and .psb. Even then I had to reduce it in size to 65,000 by 14,000 and save it compressed to keep it under the 4 Gig barrier. As it turned out, my output image file size from PTGui was only 1.5 Gigs. But I could open that file in Photoshop CS4, convert it to 16-bit and make three layers that I could edit which could be saved compressed as a 4.23 Gig .tiff.

Message edited by author 2009-04-05 16:41:34.
 04/05/2009 04:56:21 PM · #7
Steve, you are correct, I could not have saved it in JPEG... I don't have the files anymore, my memory must be misleading me. I must have used TIFF, I know it was a single layer. Just for fun, I tried creating and saving a 100,000 pixel wide by 10,000 pixel tall (1.0 Gpx) TIFF image in CS4, and that worked.
My comments on file size limitations reflect what I know about the NTFS and FAT disk formats, but do not include any application-specific limitations.
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