Verification File List Database Access API for Bob
The Verification Filelist database API provides mechanisms to create an API for a verification database and protocol, the user providing file lists.
You would normally not install this package unless you are maintaining it. What you would do instead is to tie it in at the package you need to use it. There are a few ways to achieve this:
- You can add this package as a requirement at the setup.py for your own satellite package or to your Buildout .cfg file, if you prefer it that way. With this method, this package gets automatically downloaded and installed on your working environment, or
- You can manually download and install this package using commands like easy_install or pip.
The package is available in two different distribution formats:
- You can download it from PyPI, or
- You can download it in its source form from its git repository. When you download the version at the git repository, you will need to run a command to recreate the backend SQLite file required for its operation. This means that the database raw files must be installed somewhere in this case. With option a you can run in dummy mode and only download the raw data files for the database once you are happy with your setup.
You can mix and match points 1/2 and a/b above based on your requirements. Here are some examples:
Modify your setup.py and download from PyPI
That is the easiest. Edit your setup.py in your satellite package and add the following entry in the install_requires section (note: ... means whatever extra stuff you may have in-between, don’t put that on your script):
install_requires=[ ... "xbob.db.verification.filelist", ],
Proceed normally with your bootstrap/buildout steps and you should be all set. That means you can now import the namespace xbob.db.verification.filelist into your scripts.
Modify your buildout.cfg and download from git
You will need to add a dependence to mr.developer to be able to install from our git repositories. Your buildout.cfg file should contain the following lines:
[buildout] ... extensions = mr.developer auto-checkout = * eggs = bob ... xbob.db.verification.filelist [sources] xbob.db.verification.filelist = git https://github.com/bioidiap/xbob.db.verification.filelist.git ...
Creating file lists
The initial step for using this package is to provide file lists specifying the world (train), development and evaluation set to be used by the biometric verification algorithm. The following files need to be created:
- For training:
world file, with default name train_world.lst, and default subdirectory norm. It is a 2-column file with format:
two (optional) world files, with default names train_optional_world_1.lst and train_optional_world_2.lst, and default subdirectory norm. The format is the same as for the world file. These files are not needed for the most of the face recognition algorithms, hence, they need to be specified only if the algorithm uses them.
- For enrollment:
two model files for the development and evaluation set, with default name for_models.lst and default subdirectories dev and eval respectively. They are 3-column files with format:
filename model_id client_id
- For scoring:
1.a. two probe files for the development and evaluation set, with default name for_probes.lst and default subdirectories dev and eval respectively. These files need to be provided only if the scoring is to be done exhaustively, meaning by creating a dense probe/model scoring matrix. They are 2-column files with format:
1.b. two score files for the development and evaluation set, with default name for_scores.lst and default subdirectories dev and eval respectively. These files need to be provided only if the scoring is to be done selectively, meaning by creating a sparse probe/model scoring matrix. They are 4-column files with format:
filename model_id claimed_client_id client_id
two (optional) files for t-score normalization for the development and evaluation set, with default name for_tnorm.lst and default subdirectories dev and eval respectively. They are 3-column files with format:
filename model_id client_id
two (optional) files for z-score normalization for the development and evaluation set, with default name for_znorm.lst and default subdirectories dev and eval respectively. They are 2-column files with format:
The verification queries will use either only the probe or only the score files, so only one of them is mandatory. In case both probe and score files are provided, the user should set the parameter use_dense_probe_file_list, which specifies the files to consider, when creating the object of the Database class.
If the database does not provide an evaluation set, the scoring files can be ommited. Similarly, if the user only define for scoring files and omit the remaining ones, the only valid queries will be scoring-related ones.
The summarized structure of the base directory (here denoted as basedir) containing all the files should be like this:
basedir -- norm -- train_world.lst | |-- train_optional_world_1.lst | |-- train_optional_world_2.lst | |-- dev -- for_models.lst | |-- for_probes.lst | |-- for_scores.lst | |-- for_tnorm.lst | |-- for_znorm.lst | |-- eval -- for_models.lst |-- for_probes.lst |-- for_scores.lst |-- for_tnorm.lst |-- for_znorm.lst
Protocols and file lists
When you instantiate a database, you have to specify the base directory that contains the file lists. If you have only a single protocol, you could specify the full path to the file lists described above as follows:
>>> db = xbob.db.verification.filelist.Database('basedir/protocol')
Next, you should query the data, WITHOUT specifying any protocol:
Alternatively, if you have more protocols, you could do the following:
>>> db = xbob.db.verification.filelist.Database('basedir') >>> db.objects(protocol='protocol')
When a protocol is specified, it is appended to the base directory that contains the file lists. This allows to use several protocols that are stored in the same base directory, without the need to instantiate a new database. For instance, given two protocols ‘P1’ and ‘P2’ (with filelists contained in ‘basedir/P1’ and ‘basedir/P2’, respectively), the following would work:
>> db = xbob.db.verification.filelist.Database('basedir') >> db.objects(protocol='P1') # Get the objects for the protocol P1 >> db.objects(protocol='P2') # Get the objects for the protocol P2
Note that if you use several protocols as explained above, the scoring part should be defined in the same way for all the protocols, either by using for_probes.lst or for_scores.lst. This means that at the time of the database instantiation, it will be determined (or specified using the use_dense_probe_file_list optional argument), whether the protocols should use the content of for_probes.lst or for_scores.lst. In particular, it is not possible to use a mixture of those for different protocols, once the database object has been created.
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