We have discussed optical flow previously. It is an algorithm-based stitching process which analyzes a shot and matches geometric lines in images together in order to remove parallax mismatches and distortions. Here we are looking at the options on the market.
In the above image, we can see a common issue with image based stitching. Across a stitch line, there are parallax issues meaning the geometry of the image doesn’t line up. Optical flow works by analyzing multiple frames and extracting information from those selection of frames to apply information to a frame before moving on to processing the next frame.
MistkaVR is a relatively new software which has won many fans. Its ability to manipulate image projections, accurate control of masking points and support for a wide range of lens and camera types makes it relatively easy to use.
The optical flow system is relatively easy to implement, essentially a tick of a button to apply and can be used in conjunction with marking and control point adjustments. The software is missing key frame control, however a new stereo suite add-on is coming soon which looks especially useful.
The software is on a subscription basis of around 60 Euro per month, and can be bought on a month-by-month basis, which is useful for those on short one-off projects.
Kolor AVP 3.0
Kolor is the established leader in stitching software. The setup is familiar to most professionals at this point and includes keyframe ability and some basic stereo controls.
In the latest 3.0 update, they have included their own optical flow update called D.warp. This algorithm works on cameras with 3 lenses or more and is excellent at matching lines. The downside is that at this time, optical flow disables the ability to amend masking and control points on a shot. D.warp enables an option of frame by frame for extensive process intensive optical flow, or using one initial frame of reference.
The cost of almost 700 Euro is a one-off outright purchase and the software is stable and easy to use.
Z Cam Wonderstitch
We have seen a number of Facebook 360 algorithm based software come to market. Z cam continue to update their Wonderstitch software. Unfortunately licensed to a single camera, the software is relatively well configured specifically to the S1 and S1 Pro and they are reducing the amount of artifacts showing up in stitching.
InstaPro 360 Stitcher
The stitching software for the InstaPro features optical flow matching. The stitching software works with PTGui or Giga for any control of images, but this does not work in combination with the optical flow.
Kandao also provide software for their Obsidian camera which closely resembles the InstaPro stitching software in form and algorithm quality.
All of the above digital image stitchers now support graphics card processing support, greatly speeding up the process.
Optical flow is the future of 360 video, making the post process much simpler and videos more natural and more effective. It will take time for the algorithms to evolve for all situations, but this relatively new development is a huge step forwards in the 360 technology market.