Horizontal panoramas have been popular for while, but it wasn't until drones took to the skies that vertical panoramas have started to take off. On the ground, the vertical range of the viewpoint is very limited and usually isn't enough to create a worthwhile vertical pano, especially since today's wide angle lenses can handle the range just fine. But at 400 ft, this all changes. Looking straight down suddenly becomes interesting. In fact, you have at least 90 degrees of perspective to play with. Combining a few of these photos together gives you a vertical pano that really articulates the view of the drone in a beautifully distorted sort of way. The picture draws the viewer's eyes to the bottom and takes it slowly upwards until the viewer is staring at the horizon. Here's a guide to creating stunning vertical panoramas.
The basics of a vertical panorama are no different than a horizontal one. Just take a few overlapping photos and merge them together. During the capture, here are some things to keep in mind:
Overlap photos a lot, but not too much
Panorama stitching software works by matching features of two photos together. The more you overlap your shots, the more the software has to match, and the more likely that your panorama will turn out well. I aim for about a 40% overlap between my shots, and about 4-6 shots overall. Too much overlap can actually backfire and give the software too many decisions to make and it sometimes fails.
Consider using manual mode
Manual mode is important when creating panoramas because it preserves the camera settings between shots, and hence the exposure. Automatic mode may alter the exposure between shots and makes features more difficult to match. This is much easier for horizontal shots, where the desired exposure is usually not too different as you pan around. However, on vertical panos, the desired exposure can change dramatically as you start looking at the shadowy ground and turn up to look at the bright sky. You'll have to make a decision as to whether you would prefer to have a slightly washed out sky or change the exposure a little and risk the pano not matching, but usually there is a good in-between spot.
Here's an example of a 6-shot vertical pano pre-merge
Now that you've captured all your photos, it's time to merge them together. You'll want to use some good editing software like Lightroom to handle the merging. There are plenty of free options, but many of them struggle with creating panoramas in the vertical direction and miss some of the advanced processing that really makes Lightroom worth the price. Pro-tip if your software can't handle vertical panos: Rotate the pictures 90 degrees to fake a horizontal merge - the results may be better.
Apply a Lens Profile
Before you merge the photos, you have the ability in Lightroom to correct slight distortions in the camera from DJI drones and others. This should be a normal part of your workflow, but it is especially important for panos, where lens distortion can worsen when combining photos. Make sure to apply the correction before the merge.
Lightroom has 3 different perspectives it can use to merge the photos - Spherical, Cylindrical, and Perspective. Perspectival rarely works well for vertical panos, so you have the latter two to choose from. I usually like the look of Cylindrical better, but it's more of an individual preference.
Lightroom CC also has a new optional features that "wraps" the merged photo borders so that no content is lost in the cropping. This gives the photo a somewhat warped look, but preserves much more of the content for a wider view. Here is an example of the two extremes:
Now that you have a merged photo, you will probably want to apply some light edits. Particularly, you may want to adjust the shadows and highlights to neutralize the different lighting across the individual photos. I usually reduce the exposure above the horizon as well. The final result now looks like this: