- A richer Problem API.
- DynamicNumericDiffCostFunction.
- Faster ITERATIVE_SCHUR solver.
- Faster SCHUR_JACOBI preconditioner.
- Faster Jacobian evaluation.
- Faster visibility based preconditioning using single linkage clustering.
Also re-wrote rules for unordered collections detection,
should work on all platforms and compilers now :)
For Blender this release is interesting because of:
- Covariance estimation (not used in Blender yet, but now we
might use it for keyframe selection instead of havingown
implementation).
- Significant performance improvements to loss function and
dense linear solvers and automatic differentiation.
Unfortunately, didn't notice speedup of tracking itself,
but camera reconstruction now happens around 2 times faster
on my laptop,
- Better inner iteration step acceptance and stopping.
This brings a fixes for threading issue in BLAS
making BA step more robust (there were some in-detemrinacy
caused by this threading issue).
Also brings some optimizations, which does not directly
affect on blender.
Thins brings up some speed improvements:
SPARSE_SCHUR is approx 1.3-1.5x times faster
ITERATIVE_SCHUR is approx 1.2x times faster
For blender this means camera solution go a bit
faster now. Would not have affect on tracking
speed.
This is helpful because it brings CHOLMOB-free ITERATIVE_SCHUR and
SCHUR_JACOBI which is really nice for new upcoming bundle adjustment.
If also includes all the local fixes we made locally.
There're lots of other improvements/fixed which are not currently
would be so much visible in Blender, but which opens doors for some
great improvements in future.
This should contain real fixes for Windows, making it more robost and hopefully
faster (due to proper collection port) on that platform.
Also hack to fix Eigen alignment shouldn't be needed anymore.
Also on platforms which have got broken TR1 collections it's better to define
CERES_NO_TR1 instead of using Boost hacks. Made changes to Scons and CMake,
but can not check if this indeed works since i don't have OSX here.
Currently only put sources of Ceres library into extern/libmv/third_party and
setup CMake and SCons building systems.
Integration details:
- Even CMake build files are not re-used from Ceres's trunk: they're using some
automatic stuff detection like glog, pthreads, protobuf and so and it's not
so clear how to re-use that files without modifications.
And IMO it's easier if build files are getting re-generated automatically to
match Blender-specific setup rather than keeping changes made locally in
Blender in sync when re-bundling Ceres library. Especially in case when it's
already needed to support SCons build system.
- Integrated only actual sources, all tests were stripped. Probably it'll be nice
to have them, but they'll need clear integration with current module test stuff
in Blender.
- Suitesparse was disabled. It'll help a lot having it, but there are some difficulties
making cholmod working fine on windows. Would be added in future
- collections_port.cc was also stripped. It's not used by Ceres's upstream and
it gives compilation error (undefined uint32 -- looks like namespace issue).
- Currently all schur eliminators are included. Not sure if it makes sense,
also not sure if it makes sense having them switchable on and off -- IMO better
to have single configuration which works and does not require special tweaks
after everything was set up.
To bundle updated version of Ceres:
- Go to extern/libmv/third_party/ceres folder
- Run ./bundle.sh
This will checkout fresh Ceres snapshot of Windows branch (which is currently
most interesting from integration into Blender POV), apply all patches listed
in patches/series and copy needed files into Blender's working copy. This will
also re-generate CMake/SCons build rules.
If you'll need extra files from Ceres repository which are not present in
Blender, you'll need to copy them manually and then run ./mkfiles.sh from
extern/libmv/third_party/ceres folder which will update list of files used
by Blender.
Thanks to Leir Mierle and Sameer Agarwal (and all others who helped developing
Ceres) this library and thanks to Keir Mierle with help integrating it into Blender!
