Chapter 34: Stitching overview

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Excerpt from Chapter 34: Stitching overview, page 169

...Before you can begin editing your footage as you would in a traditional video project, you need to convert your ingested and organized image files into stitched panoramas. If you’re not using a camera that automatically stitches your files for you (as described in the previous chapter), this step can be surprisingly complicated. 

The overall goal of combining the various source files into one final output requires a number of individual steps. Depending on the method you use to perform this action (described in Chapter 35: Stitching methods and tools), some of these steps may be automatic or otherwise hidden from you. The steps are not necessarily performed exactly in this order, but all of these steps must be performed:

Step 1: Synchronize

First, you must synchronize the multiple source files (in case the camera start-stop times weren’t perfectly coordinated), so that, for example, frame 10 of camera A lines up with frame 10 of camera B, and so on. If the files aren’t synced, the individual pieces of your patchwork may never properly line up.  

Step 2: Remove lens distortion

Next, you need to remove the distortion created by the wide-angle lenses used in 360° cameras. Such distortion causes objects in the center of the frame to appear tiny and objects near the edge of the frame to appear large. The most extreme wide-angle lenses are called fisheye lenses, where the entire scene is captured in a circular image saved in the middle of the rectangular sensor. Apply a reverse distortion to neutralize the distortion build into the shot.  

Tip: Most software has preset distortions for this purpose
labeled with the name and focal length of specific lenses. For this, it’s important to know which lens your camera utilizes.

Step 3: Stabilize

In some cases, you may need to apply image stabilization—which must be done on the individual camera shots before the files are stitched. If you try to stabilize the stitched master file, you’ll create seams or other errors around the edges of the latlong boundary.

Step 4: Match colors

To create a smooth, continuous-looking stitched file you need to ensure that the brightness and color settings are matched across all the camera source files. This can be challenging if you’re shooting in an environment where the lighting is inconsistent in different directions (such as a room with a bright window on one side and a dark hallway on the opposite side).

 

Image stabilization: A process to reduce shakiness caused by an unstable camera.

Latlong (latitudinal-longitudinal): Stretching a spherical image into a flat rectangle (similar to the way a world map represents the spherical Earth). Also called equirectangular.

The sun is creating a glare on one lens causing a color mismatch across the stitch lines.

The sun is creating a glare on one lens causing a color mismatch across the stitch lines.

Step 5: Stitch...