Hugin – Matthew Petroff

Stabilizing 360 Video with Hugin

Matthew Petroff — Wed, 30 Nov 2016 23:51:08 +0000

Although there are plenty of tools that work well for stabilizing regular video, there aren’t any good ones for stabilizing 360 degree video. As I was unable to find any freely available software that worked, I used various command line tools from Hugin and FFmpeg. Although this worked, it was extremely slow and had some issues with the horizon drifting.¹ I can’t really recommend the approach, but I figured I’d post the technique in case anyone finds it to be useful. Hopefully Facebook with open source their 360 video stabilization, since it seems much better.

# Extract frames from original video
ffmpeg -i video.webm frame%03d.png

# Create Hugin project with frames
pto_gen -o project.pto -p 4 -f 360 frame*.png

# Find control points between adjacent frames
cpfind --linearmatch -o ctrlpoints.pto project.pto

# Remove bad control points (optional)
cpclean -p -o clean.pto ctrlpoints.pto

# Optimize fit
autooptimiser -p -o optimized.pto clean.pto

# Change output size to match input and change output mode to only remap images
pano_modify --canvas=AUTO --output-type=REMAPORIG -o output.pto optimized.pto

# Stitch output
nona -o output output.pto

# Convert remapped frames back into video
ffmpeg -framerate 30 -i output%04d.tif -c:v libvpx -b:v 10M output-no-audio.webm

# Copy audio
ffmpeg -i output-no-audio.webm -i video.webm -map 0:v -map 1:a -c:v copy -c:a libvorbis output.webm

Manually adding some horizontal line control points in Hugin helped in this regard. ↩

Peering Down

Matthew Petroff — Fri, 16 Jan 2015 06:00:10 +0000

Two years ago, I took a large set of photos at the George Peabody Library. Among those were a very wide angle image looking up at the skylight and an image looking down. The latter was taken with a point-and-shoot camera suspended between the sixth floor railings with the help of fishing line and office supplies. Unfortunately, the field of view was much too narrow, leaving the stacks out completely, so the photo fell short of my vision for it, and it didn’t complement the photo looking up. I needed to use my DSLR and fisheye lens, but there was no way the previous method would have supported it. However, I just revisited this idea and finally got the photo I wanted.

This time, I designed an aluminum rig to hold the DSLR and suspended it between the railings using parachute cord. After stringing the cord across the atrium and pulling it taut with a trucker’s hitch, I attached the camera and pulled the rig to the center of the atrium using fishing line. Once the camera stopped swinging, I took around a dozen exposure-bracketed sets of photos via USB tethering and then took everything down. Finally, I used Hugin to correct the lens distortion and small misalignments for three bracketed sets, masking out people who were moving in each set; Enblend and Enfuse were used to create the final image, which was then cropped.

Day Student Lounge Panorama

Matthew Petroff — Fri, 29 Jul 2011 02:33:53 +0000

For my four years at Taft, this was my home away from home. The Day Student Lounge in all its glory: May 28, 2011.

And an interactive version:

Sidewalk Chalk

Matthew Petroff — Sat, 18 Jun 2011 01:18:25 +0000

Prior to graduation, the underclassmen wrote the names of all of the graduating seniors on the various paths outside in sidewalk chalk. Wanting to remember this moment, I set out to document it and photographed the entire path with an 8mm fisheye lens. I then pruned the more than 200 images down to 135 and, using Hugin’s mosaic mode and more than 1000 manually selected control points, was able to stitch together the photos into one 678.9 megapixel image after many, many hours of work. Here I present the results.

Taft Class of 2011 Names:
https://mpetroff.net/files/openzoom/taft-class-of-2011/

Taft Class of 2011 Initials:
https://mpetroff.net/files/openzoom/taft-class-of-2011-initials/