The Wide Angle: Creating Seamless Panoramas

[doubleconvex]

This tutorial was written up by DoubleConvex. As a result of the forum limitation of no more than 4 images per tutorial, I can only post part of the tutorial here. The complete tutorial is freely available on my website.



Standard digital cameras will invariably take a more than decent single frame. The first major technique that every digital photographer invariably attempts (and thereafter uses most often) is creating a panoramic image. This tutorial provides some simple shooting tips and a primer on using digital post processing techniques to create seamless panoramics.

In general, one can take the composite images of a panorama using any digital camera. Most new digital cameras have a Panorama Assist mode. It isn't essential to have the camera set to this mode. However, capturing a decent panoramic image requires the use of a tripod.

Let's say that you've found your location and subject that you want to capture a panoramic image of. It's important that you have your tripod calibrated to be level as you rotate (or pan) you camera from one side to the other. Most decent tripods come with a spirit level on each axis of movement. If you're using a tripod without a spirit level, or are placing your camera on a stationary object, panning it across your field of view while maintaining a constant position of a reference line (say, the horizon) is a crude but effective manner of maintaining some degree of level in your final image.

Panorama images need not be horizontal. They can also be vertical, and in some cases, may even be a 360° image. Horizontal and vertical panoramas can be saved as still images (JPEG, TIFF, BMP formats). 360° panoramas are typically stored as Quick-Time VR files.

Once you have your camera mounted on its tripod or level base, there are a few things that are worth noting before you begin shooting:

• Use a manual exposure setting: It is of paramount importance that you do not use the camera in "AUTO". As you pan your camera across the scene, the angle at which light hits your camera's lens will change, and along with it, the amount of light. When in automatic mode, your camera will change the exposure time of each image, thereby imparting a somewhat different colour tone. Using images shot at different exposures in the final composite, will impart bands of different tones.
• Use a manual focus setting: When in automatic mode, your camera will tend to change its focus based on the elements of each composite image. Changes in focal lengths across individual images will result in fuzzy, out-of-focus areas in the final composite panorama. Set your camera to a fixed focal length, and shoot consistently with the same setting for all the composite images.
• Set your camera's white balance to a manual setting: It is imperative that you do not use an automatic white balance setting. Once again, for a panoramic image, it is likely that light conditions will vary across the image. An automatic white balance setting will impart different colour tones in different regions of the composite panorama.
• Do not use a flash: One of the worst things that you can do with a panoramic image is firing a flash. Doing so will result in large dark underexposed areas along with large bright overexposed regions.
• Do not change the size or quality of composite images: A composite panoramic image is composed of multiple images that must be of the same size and quality.
• Shoot quickly: Elements across a panoramic image (clouds, people and so on) tend to move. It's important that you capture all the composite images of your panorama quickly - ideally, under 30 seconds. This can be very tricky with long exposure shots.
• Get the appropriate amount of overlap: A composite panorama must have some overlap among its component images. A good rule of thumb is between 25 to 50 percent of the image. I personally tend to go for approximately a 33% (or one-third) overlap.

If you've followed these steps so far, you should have your set of component images to assemble your panorama from. There are a range of panoramic image processors available. I have used several including Ulead cool 360°, Canon Photostitch, and PanoramaStudio - but the best luck that I have had has been with ArcSoft Panorama Maker which I have stuck with. Most of these applications are fairly cheap (less than US$100); ArcSoft Panorama Maker is bundled for free with Nikon cameras. A pro-version, ArcSoft Panorama Maker Pro, is also available, which offers support for tiled panoramas. The advantage of the ArcSoft products is their support for RAW image formats, and by extension, HDR panoramas. This tutorial focuses on how to use ArcSoft Panorama Maker to compose a seamless panorama

The image below illustrates Panorama Maker's interface. Note that the images shown here are all in RAW format.



These component images were all shot using a tripod in RAW format. Note that they have also been shot in order from left to right. This is not an issue. Component images can be shot in the reverse order. Panorama Maker will allow you to re-order you images at a later stage. Also note the options in the bottom left corner which allow you to create vertical panoramas and 360° QTVRs.

The first step involves selecting the component images. Panorama maker is typically intelligent enough to identify an image group. It does this using the EXIF settings and some rudimentary image analysis. Once you've selected your component images (note the green check marks on each select component image) click "Next"



Panorama Maker will load the component images into its interface and provide options to reorder them in the correct order. Reordering is as simple as dragging and dropping the images into their correct positions.



Once the images have been placed in their correct order, click on the "Stitch" button in the bottom right hand corner. Panorama Pro will process the images and present a composite panorama, as shown in the image below.

I've had to truncate the tutorial here as a result of the forum restriction of no more than 4 images to a single post. The full tutorial with complete relevant illustrations are avaible at DoubleConvex's website. Do you have a favorite panorama assembly software package but no component images to try out? The archive of images used in this example are also available on my website. (Scroll to the bottom: The link is in the section highlighted in green).

[Nicole]

Don't forget, you can always reply to your own post to finish the tutorial

I was kind of confused at first when the "example" picture was so different from the pieces Yeah, I know, different picture.

[doubleconvex]

Originally Posted by Nicole

Don't forget, you can always reply to your own post to finish the tutorial

D'oh! Yeah - I should have figured that one out!

[inkista]

Just a few added notes from someone who's gotten too deeply into panostitching.

If the ArcSoft pano software is anything like Canon's Photostitch, I'd recommend looking into Hugin instead (if you have to go with opensource/freeware), or PTGui if you have money to blow. I started out stitching panos in Photostitch, and found that a Panorama Tools-based stitcher was more my speed for several reasons:

1. I could turn the camera into portrait mode for more vertical coverage.
2. I could shoot a grid of photos, rather than just a single row/column or four-up layout. This can severely ease the whole "leveled horizon" thing by giving you enough elbow room to rotate and stitch.
3. I could stitch both cylindrical and equirectangular (VR, 360x180) panos. Furthermore, I could do 360x180s with a fisheye lens.
4. Both these packages let me do HDR/exposure blending AND panostitching at the same time.
5. PT-based packages typically include enblend to blend over the seams.
6. Perspective correction and viewpoint correction can be done before/after stitching to fix curved horizons that come from yaw/pitch/roll errors while handholding.
7. Layered output so I can fix ghosts/clones either ahead of time with alpha masks, or after the stitch.

Just saying, if you're going to get heavily into stitching panos, it might be worthwhile to take a look beyond just the basic stitching software that's out there to something a bit more advanced. There are learning curves, and the interfaces are more complex, but the added function can be worth it.