Basic implementation

README.rst

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+Scaffold Fitter
+===============
+
+Scaffold/model fitter using OpenCMISS-Zinc.
+
+For the interim, install with the following command::
+
+    pip install -e .
+
+Requires the following Python libraries to be installed:
+
+- opencmiss.zinc (manual install from opencmiss.org)
+- github.com/OpenCMISS-Bindings/opencmiss.utils

setup.py

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+from setuptools import setup, find_packages
+import os
+import io
+
+SETUP_DIR = os.path.dirname(os.path.abspath(__file__))
+
+# List all of your Python package dependencies in the
+# requirements.txt file
+
+def readfile(filename, split=False):
+    with io.open(filename, encoding="utf-8") as stream:
+        if split:
+            return stream.read().split("\n")
+        return stream.read()
+
+readme = readfile("README.rst", split=True)[3:]  # skip title
+# For requirements not hosted on PyPi place listings
+# into the 'requirements.txt' file.
+requires = [
+    # minimal requirements listing
+    "opencmiss.utils >= 0.2",
+    "opencmiss.zinc"  # not yet on pypi - need manual install from opencmiss.org
+]
+source_license = readfile("LICENSE")
+
+setup(
+    name="scaffoldfitter",
+    version="0.1.1",
+    description="Scaffold/model geometric fitting library using OpenCMISS-Zinc.",
+    long_description="\n".join(readme) + source_license,
+    classifiers=[
+        "Development Status :: 3 - Alpha",
+        "Programming Language :: Python",
+        "Topic :: Scientific/Engineering :: Medical Science Apps."
+    ],
+    author="Auckland Bioengineering Institute",
+    author_email="[email protected]",
+    url="https://github.com/ABI-Software/scaffoldfitter",
+    license="Apache Software License",
+    packages=find_packages("src"),
+    package_dir={"": "src"},
+    include_package_data=True,
+    zip_safe=False,
+    install_requires=requires,
+    )

src/scaffoldfitter/fitterstepalign.py

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+"""
+Fit step for gross alignment and scale.
+"""
+
+from opencmiss.utils.zinc.field import assignFieldParameters, createFieldsTransformations
+from opencmiss.utils.zinc.finiteelement import getNodeNameCentres
+from opencmiss.utils.zinc.general import ChangeManager
+from opencmiss.zinc.field import Field
+from opencmiss.zinc.optimisation import Optimisation
+from opencmiss.zinc.result import RESULT_OK, RESULT_WARNING_PART_DONE
+from scaffoldfitter.fitter import Fitter, FitterStep
+
+class FitterStepAlign(FitterStep):
+
+    _jsonTypeId = "_FitterStepAlign"
+
+    def __init__(self, fitter : Fitter):
+        super(FitterStepAlign, self).__init__(fitter)
+        self._alignMarkers = False
+        markerNodeGroup, markerLocation, markerCoordinates, markerName = fitter.getMarkerModelFields()
+        markerDataGroup, markerDataCoordinates, markerDataName = fitter.getMarkerDataFields()
+        if markerNodeGroup and markerLocation and markerCoordinates and markerName and \
+            markerDataGroup and markerDataCoordinates and markerDataName:
+            self._alignMarkers = True
+        self._rotation = [ 0.0, 0.0, 0.0 ]
+        self._scale = 1.0
+        self._translation = [ 0.0, 0.0, 0.0 ]
+
+    @classmethod
+    def getJsonTypeId(cls):
+        return cls._jsonTypeId
+
+    def decodeSettingsJSONDict(self, dct : dict):
+        """
+        Decode definition of step from JSON dict.
+        """
+        assert self._jsonTypeId in dct
+        self._alignMarkers = dct["alignMarkers"]
+        self._rotation = dct["rotation"]
+        self._scale = dct["scale"]
+        self._translation = dct["translation"]
+
+    def encodeSettingsJSONDict(self) -> dict:
+        """
+        Encode definition of step in dict.
+        :return: Settings in a dict ready for passing to json.dump.
+        """
+        return {
+            self._jsonTypeId : True,
+            "alignMarkers" : self._alignMarkers,
+            "rotation" : self._rotation,
+            "scale" : self._scale,
+            "translation" : self._translation
+            }
+
+    def isAlignMarkers(self):
+        return self._alignMarkers
+
+    def setAlignMarkers(self, alignMarkers):
+        """
+        :param alignMarkers: True to automatically align to markers, otherwise False.
+        """
+        self._alignMarkers = alignMarkers
+
+    def getRotation(self):
+        return self._rotation
+
+    def setRotation(self, rotation):
+        """
+        :param rotation: List of 3 euler angles in radians, order applied:
+        0 = azimuth (about z)
+        1 = elevation (about rotated y)
+        2 = roll (about rotated x)
+        """
+        assert len(rotation) == 3, "FitterStepAlign:  Invalid rotation"
+        self._rotation = rotation
+
+    def getScale(self):
+        return self._scale
+
+    def setScale(self, scale):
+        """
+        :param scale: Real scale.
+        """
+        self._scale = scale
+
+    def getTranslation(self):
+        return self._translation
+
+    def setTranslation(self, translation):
+        """
+        :param translation: [ x, y, z ].
+        """
+        assert len(translation) == 3, "FitterStepAlign:  Invalid translation"
+        self._translation = translation
+
+    def run(self):
+        """
+        Perform align and scale.
+        """
+        modelCoordinates = self._fitter.getModelCoordinatesField()
+        assert modelCoordinates, "Align:  Missing model coordinates"
+        if self._alignMarkers:
+            self._doAlignMarkers()
+        fieldmodule = self._fitter._fieldmodule
+        with ChangeManager(fieldmodule):
+            # rotate, scale and translate model
+            modelCoordinatesTransformed = createFieldsTransformations(
+                modelCoordinates, self._rotation, self._scale, self._translation)[0]
+            fieldassignment = self._fitter._modelCoordinatesField.createFieldassignment(modelCoordinatesTransformed)
+            result = fieldassignment.assign()
+            assert result in [ RESULT_OK, RESULT_WARNING_PART_DONE ], "Align:  Failed to transform model"
+            self._fitter.updateModelReferenceCoordinates()
+            del fieldassignment
+            del modelCoordinatesTransformed
+        self._fitter.calculateDataProjections()
+        self.setHasRun(True)
+
+    def _doAlignMarkers(self):
+        """
+        Prepare and invoke alignment to markers.
+        """
+        fieldmodule = self._fitter._fieldmodule
+        markerGroup = self._fitter.getMarkerGroup()
+        assert markerGroup, "Align:  No marker group to align with"
+        markerPrefix = markerGroup.getName()
+        modelCoordinates = self._fitter.getModelCoordinatesField()
+        componentsCount = modelCoordinates.getNumberOfComponents()
+
+        markerNodeGroup, markerLocation, markerCoordinates, markerName = self._fitter.getMarkerModelFields()
+        assert markerNodeGroup and markerCoordinates and markerName, "Align:  No marker group, coordinates or name fields"
+        modelMarkers = getNodeNameCentres(markerNodeGroup, markerCoordinates, markerName)
+
+        markerDataGroup, markerDataCoordinates, markerDataName = self._fitter.getMarkerDataFields()
+        assert markerDataGroup and markerDataCoordinates and markerDataName, "Align:  No marker data group, coordinates or name fields"
+        dataMarkers = getNodeNameCentres(markerDataGroup, markerDataCoordinates, markerDataName)
+
+        # match model and data markers, warn of missing markers
+        markerMap = {}
+        for name, modelx in modelMarkers.items():
+            datax = dataMarkers.get(name)
+            if datax:
+                markerMap[name] = ( modelx, datax )
+        if self.getDiagnosticLevel() > 0:
+            for name in modelMarkers:
+                datax = dataMarkers.get(name)
+                if datax:
+                    print("Align:  Found marker " + name + " in model and data")
+            for name in modelMarkers:
+                if not markerMap.get(name):
+                    print("Align:  Model marker " + name + " not found in data")
+            for name in dataMarkers:
+                if not markerMap.get(name):
+                    print("Align:  Data marker " + name + " not found in model")
+
+        self._optimiseAlignment(markerMap)
+
+    def _optimiseAlignment(self, markerMap):
+        """
+        Calculate transformation from modelCoordinates to dataMarkers
+        over the markers, by scaling, translating and rotating model.
+        On success, sets transformation parameters in object.
+        :param markerMap: dict name -> (modelCoordinates, dataCoordinates)
+        """
+        assert len(markerMap) >= 3, "Align:  Only " + str(len(markerMap)) + " markers - need at least 3"
+        region = self._fitter._context.createRegion()
+        fieldmodule = region.getFieldmodule()
+        with ChangeManager(fieldmodule):
+            modelCoordinates = fieldmodule.createFieldFiniteElement(3)
+            dataCoordinates = fieldmodule.createFieldFiniteElement(3)
+            nodes = fieldmodule.findNodesetByFieldDomainType(Field.DOMAIN_TYPE_NODES)
+            nodetemplate = nodes.createNodetemplate()
+            nodetemplate.defineField(modelCoordinates)
+            nodetemplate.defineField(dataCoordinates)
+            fieldcache = fieldmodule.createFieldcache()
+            for name, positions in markerMap.items():
+                modelx = positions[0]
+                datax = positions[1]
+                node = nodes.createNode(-1, nodetemplate)
+                fieldcache.setNode(node)
+                result1 = modelCoordinates.assignReal(fieldcache, positions[0])
+                result2 = dataCoordinates.assignReal(fieldcache, positions[1])
+                assert (result1 == RESULT_OK) and (result2 == RESULT_OK), "Align:  Failed to set up data for alignment to markers optimisation"
+            del fieldcache
+            modelCoordinatesTransformed, rotation, scale, translation = createFieldsTransformations(modelCoordinates)
+            # create objective = sum of squares of vector from modelCoordinatesTransformed to dataCoordinates
+            markerDiff = fieldmodule.createFieldSubtract(dataCoordinates, modelCoordinatesTransformed)
+            objective = fieldmodule.createFieldNodesetSumSquares(markerDiff, nodes)
+            assert objective.isValid(), "Align:  Failed to set up objective function for alignment to markers optimisation"
+
+        # future: pre-fit to avoid gimbal lock
+
+        optimisation = fieldmodule.createOptimisation()
+        optimisation.setMethod(Optimisation.METHOD_LEAST_SQUARES_QUASI_NEWTON)
+        optimisation.addObjectiveField(objective)
+        optimisation.addIndependentField(rotation)
+        optimisation.addIndependentField(scale)
+        optimisation.addIndependentField(translation)
+
+        result = optimisation.optimise()
+        if self.getDiagnosticLevel() > 1:
+            solutionReport = optimisation.getSolutionReport()
+            print(solutionReport)
+        assert result == RESULT_OK, "Align:  Alignment to markers optimisation failed"
+
+        fieldcache = fieldmodule.createFieldcache()
+        result1, self._rotation = rotation.evaluateReal(fieldcache, 3)
+        result2, self._scale = scale.evaluateReal(fieldcache, 1)
+        result3, self._translation = translation.evaluateReal(fieldcache, 3)
+        assert (result1 == RESULT_OK) and (result2 == RESULT_OK) and (result3 == RESULT_OK), "Align:  Failed to evaluate transformation for alignment to markers"