Archive translation. This article originally appeared in Digital Production 01:2017. Features, links, compatibility, licensing and availability reflect that period; verify the current plug-in before production use.
In brief: Good Spirit Graphics’ MochaBlend transferred Mocha tracking data and shapes into Cinema 4D or Blender, supporting planar-track-based 3D integration workflows.
This article originally appeared in DP 01 : 2017.
MochaBlend from Good Spirit Graphics is not a new coffee blend, but a plug-in for Cinema 4D (or Blender) that can transfer tracks and shapes from Mocha to the 3D programmes. You might ask yourself why you need this when Cinema 4D (C4D) version 18 already offers its own object tracker, but there must be a reason why 3D World Magazine named the software “Best in Class”.
Now, while Mocha is one of the best planar trackers, if not the best, the corresponding options in C4D are rather rudimentary. You have to set at least 8 or 9 conventional single-point tracks by hand and correct them if necessary in order to be able to link a 3D object to the movements of a real body in space in a reasonably reliable way. In doing so, you are confronted with all the problems that can arise due to insufficient samples or occlusions. As a rule, the whole thing will only work if you have already placed markers on the object in the real image that are easy to follow visually. This is exactly how it is demonstrated in the Maxon tutorials.
Mocha, on the other hand, only requires a reasonably flat surface to be framed by a spline in order to find its own points for tracking, follow them and verify the tracks. It never ceases to amaze what critical images Mocha can use to create useful tracks. On the basis of these tracks, MochaBlend can then calculate movement paths for objects in 3D space, transfer shapes as spatially moving splines or even reconstruct camera movements in space.
For many tasks, the MochaTracker from After Effects (AE for short) is sufficient; with its calculation of a 3D camera movement, MochaBlend even offers possibilities that Mocha itself only offers in the “Pro” version Tracking in Mocha should be started with a position that points reasonably frontally to the camera. The Pro version is only indispensable for elaborately rotoscoped masks, which MochaBlend can then convert into 3D objects in space. To export from Mocha to AE, use “After Effects Corner Pin (with Motion Blur)”; Mocha Pro has offered a format directly for MochaBlend since version 4. C4D has its own automatic 3D camera tracker for camera movements, which works better or less well than the MochaBlend method, depending on the subject.
The camera tracker in C4D requires a sufficiently large movement of the camera in space and enough valid tracking points, while the MochaBlend solver can generate a 3D camera path from a surface tracked in perspective in Mocha alone. However, this works less precisely when there are large changes in size due to camera movements in depth. The two solutions do not actually compete, but rather complement each other.
The 3D solver in Mocha Pro requires several, non-co-planar surfaces, while the solver in MochaBlend delivers good results with just one surface if the track in Mocha has worked properly. The plug-in can import the 3D track of a camera movement from Mocha Pro and convert it into a rig. You can even combine 3D camera tracks from AE and other sources, such as Boujou or Synth Eyes, in C4D with the rig from MochaBlend.
How does this work?
MochaBlend creates a suitable camera rig for each tracking (up to fifty slots are available), which is populated with the original film as a background in addition to the transferred information on image size, pixel format and duration.
After converting the track, it also contains the solution from the plug-in and can therefore be positioned flexibly in C4D without losing the relative relationships. The camera in the rig adjusts its position to the focal length, the rig is always perfectly aligned with it and it can also be moved backwards in an adapted size – a solution that also supports less experienced users well.
Inserting the background film using drag-and-drop does not always work straight away due to minor problems in C4D, sometimes you have to try again. The author will soon programme a file selection window for this. In addition, the synchronisation of some video containers in C4D does not work perfectly, in which case it is better to use image sequences. MochaBlend offers two special solvers, one for 2.5D and the other for 3D. The first is suitable for tracks in which the plane to be tracked has moved largely parallel to the camera, which may well include a change in distance. In Mocha, only translation and scale are tracked, and if the object rotates around the depth axis, rotation is also tracked. Such tracks are transferred with the 2.5D solver.
If, on the other hand, the tracked plane has been tilted in perspective (like our kitchen board), you must also track Shear and Perspective and use the 3D solver in MochaBlend. Of course, a perspective track is never completely perfect if the tracked area is not really flat. MochaBlend has its own window for the quality check.
MochaBlend is very well thought out and user-friendly, the tool tips even appear in the corresponding field in C4D, but the whole thing is not a trivial matter in its versatility. Getting started is supported by easy-to-follow video tutorials including practice material: tinyurl.com/j88e5pc. There is also a comprehensive manual in English under “Help”. Incidentally, MochaBlend retains all imported data even after a restart. However, if all 50 data slots are used for complex tracks from Mocha and kept open for immediate access, this can take up a relatively large amount of RAM, which is why the number of displayed slots can be reduced.
Roto-Shapes
The ability to transfer the original image as a camera mapping to rotoscoped outline shapes and generate a 3D object from it is very impressive. The MochaBlend Exporter is included and allows animated mask paths and shapes to be transferred from AE (and therefore also Photoshop or Illustrator) to C4D. However, if you want support for manual rotoscoping through tracking, you will need the Pro version of Mocha.
Splines can also be created on a rotated plane using a NullObject, which can even be animated by C4D. The support points of a spline can be translated to null objects in C4D, but first you should use the “Correct X-Spline Null Count” command to delete the duplicates that are created when translating the usual splines from Mocha (C4D does not recognise X-splines). The Camera Map Editor for converting the shapes into 3D is excellent, but displaying the changes in C4D requires a click on “Update”.
Of course, the object created in this way remains a flat block that is only displayed correctly from one perspective – where should the other information come from? But such objects can interact with other 3D objects and produce spectacular results in conjunction with physical simulations or the particles in C4D, as the product demo with the runner proves. A very detailed tutorial on using Roto-Shapes can be found here: vimeo.com/158491618. The next version of MochaBlend will even support animated autotrace splines from AE, which contain a changing number of support points for each image – something that didn’t work at all in 3D until now. In addition, the spline objects should be independent of the moving camera in the rig. Certainly not an easy task for developer Chris Barrett.
Comment
The integration of Cinema 4D and After Effects has long been exemplary, but MochaBlend closes the gap between Mocha and C4D on the way from two-dimensional moving images to 3D space.
For many tasks, it even saves the investment in the Pro version of Mocha.
