Thursday, 15 December 2011

Making a 'Jigsaw' Panorama

One of the most useful tools in Photoshop and Photoshop Elements is a feature called Photomerge.  As the name suggests, this has been designed for stitching panorama sections together. And it’s done this job well ever since it was first introduced in PSE (then it was upscaled to appear in Photoshop CS). In its original version, the finished Photomerge panoramas were unpredictable and required a lot of fine-tuning to get them perfectly lined up and tone matched.

This is the massive caldera of Mt Batur in Bali by Wendy Travers. Many people will be familiar with this (although rarely do you get such a clear view as this!) but few can claim to have captured the entirety of the scene. Wendy shot 30+ images on a point and shoot camera then stitched the lot together using PSE's Photomerge Panorama utility. The resulting file not only encompasses most of this massive scene (including the window ledge at extreme right), it also produces a very large file!

Once the jigsaw has finished stitching, check the layer masks (the black-and-white thumbnails to the right-hand side of the layer thumbnails) to see if there are any redundant layers (ones with no apparent content). Delete them to free up computer resources.
However, ever since the release of PSE 6.0 and a revamped version of Photomerge, it's almost easy to create eye-popping panoramas using this clever piece of computer code. So much so that the same code has been adapted in Photoshop Elements to work with face montaging (called Photomerge Faces), people montaging (called Photomerge People) and there's even a Photomerge 'scene cleaner'. This montages people, and things, OUT of a scene. To make the latter work you have to remember to shoot multiple images of the same subject preferably shot using a tripod, ensuring that the moving parts in the image, usually the people, are recorded in different parts of each section. The software then replaces the ‘busy’ parts of the frame (i.e. those sections that have people moving through them) with ‘less busy’ parts of the frame (i.e. those same sections that have no people moving through them).
One of the refreshing features of a jigsaw panorama is that they move away from the rectilinear format of most photos. The edges can be unpredictable and therefore introduce a sense of chance into the image making process. Mt Batur view jigsaw panorama by Carolyn Pettigrew.
When it comes to shooting a panorama most photographers only record a few frames before stopping the shooting process. This produces quite acceptable panoramic results. But, it’s possible to shoot multiple frames, with different focal lengths, and even at radically different angles to each other and still produce a completely stitcheable result. To a certain extent this technique relies on your computer being able to handle the massive number of calculations this entails but, if you set your camera to medium or low resolution before you start, you'll find that you can shoot up to, and including, 50 frames which are then flawlessly stitched together using Photomerge Panorama.

Hindu ceremony, Tirta Gangga, Bali by Robin Nichols
I call this process a jigsaw panorama. To me it has several advantages over the standard rectilinear frame. Every straight panorama is rectilinear. That's the nature of photography. Everything comes in a rectangular frame. However, if you shoot multiple frames of a set scene, at slightly different angles, randomly if you prefer, the stitched image that’s subsequently produced will have irregular edges. In fact it might even have large parts missing. It just depends on how careful you are when shooting each section.
Aside from a delightful randomness in the resulting shape, you'll soon find that by stitching multiple frames together (and I mean more than six) results in a truly massive picture file. The largest jigsaw panorama I have ever created came to more than 1.5 GB, although I had one student who, memorably, produced a massive 4Gb panorama! He claimed that it took his computer more than three hours to complete.
If you don't want to spend all day waiting for the computer to complete the operation I suggest you lower the resolution, either before you shoot the picture sections, or after using Photoshop Element's batch conversion utility (called Process Multiple Files). Reduce your images to 50 or 70% and then import them back into Photomerge.

Jigsaw Shooting Tips:
Remember to overlap the frames by at least 20%
Do not overlap the frames to much because this just makes the computer have to work harder
Set the lens to manual focus (so the camera does not accidentally re-focus on a near object)
Set the metering to Manual (so the exposures are all the same)

Reduce the file size by 50% to make the processing easier and faster - you will still end up with a large file.
Here was my attempt at the Mt Batur scene - I managed to cover a wider area but missed several sections in the lower slopes of the caldera! This needs another 10 or 15 sections along the base to make up the lost details!
This illustration demonstrates how the frames above overlap, or didn't in this example. I'll just have to go back and reshoot...