#63 Move functionality of DataDescriptor to VolumeDescriptor, DataDescriptor is now abstract

- add pure virtual destructor to DataDescriptor
- create VolumeDescriptor which takes over most functionality from DataDescriptor
- move static function bestCommon(...) to a free function in DescriptorUtils.h/cpp
- fix other classes and tests to return and handle VolumeDescriptors instead of DataDescriptors

benchmarks/bench_Projectors.cpp

@@ -12,6 +12,7 @@
 
 #include "Logger.h"
 #include "elsaDefines.h"
+#include "VolumeDescriptor.h"
 #include "PhantomGenerator.h"
 #include "CircleTrajectoryGenerator.h"
 
@@ -29,7 +30,7 @@ void runProjector2D(index_t coeffsPerDim)
     // generate 2d phantom
     IndexVector_t size(2);
     size << coeffsPerDim, coeffsPerDim;
-    auto phantom = DataContainer_t(DataDescriptor(size));
+    auto phantom = DataContainer_t(VolumeDescriptor(size));
     phantom = 0;
 
     // generate circular trajectory
@@ -59,7 +60,7 @@ void runProjector3D(index_t coeffsPerDim)
     // generate 2d phantom
     IndexVector_t size(3);
     size << coeffsPerDim, coeffsPerDim, coeffsPerDim;
-    auto phantom = DataContainer_t(DataDescriptor(size));
+    auto phantom = DataContainer_t(VolumeDescriptor(size));
     phantom = 0;
 
     // generate circular trajectory

benchmarks/bench_RayGenerationBench.cpp

@@ -9,6 +9,7 @@
 #define CATCH_CONFIG_ENABLE_BENCHMARKING
 
 #include <catch2/catch.hpp>
+#include "VolumeDescriptor.h"
 #include "Geometry.h"
 #include <string>
 #include <cstdlib>
@@ -47,11 +48,11 @@ TEST_CASE("Ray generation for 2D")
 {
     IndexVector_t volCoeff(2);
     volCoeff << 5, 5;
-    DataDescriptor ddVol(volCoeff);
+    VolumeDescriptor ddVol(volCoeff);
 
     IndexVector_t detCoeff(1);
     detCoeff << 5;
-    DataDescriptor ddDet(detCoeff);
+    VolumeDescriptor ddDet(detCoeff);
 
     real_t s2c = 10;
     real_t c2d = 4;
@@ -98,11 +99,11 @@ TEST_CASE("Ray generation for 3D")
 {
     IndexVector_t volCoeff(3);
     volCoeff << 5, 5, 5;
-    DataDescriptor ddVol(volCoeff);
+    VolumeDescriptor ddVol(volCoeff);
 
     IndexVector_t detCoeff(2);
     detCoeff << 5, 5;
-    DataDescriptor ddDet(detCoeff);
+    VolumeDescriptor ddDet(detCoeff);
 
     real_t s2c = 10;
     real_t c2d = 4;

elsa/core/CMakeLists.txt

@@ -10,41 +10,45 @@ set(ELSA_MODULE_EXPORT_TARGET elsa_${ELSA_MODULE_NAME}Targets)
 set(MODULE_HEADERS
         elsaDefines.h
         Cloneable.h
-        DataDescriptor.h
-        BlockDescriptor.h
-        IdenticalBlocksDescriptor.h
-        PartitionDescriptor.h
-        RandomBlocksDescriptor.h
+        Descriptors/DataDescriptor.h
+        Descriptors/DescriptorUtils.h
+        Descriptors/VolumeDescriptor.h
+        Descriptors/BlockDescriptor.h
+        Descriptors/IdenticalBlocksDescriptor.h
+        Descriptors/PartitionDescriptor.h
+        Descriptors/RandomBlocksDescriptor.h
         DataContainer.h
         DataContainerIterator.h
-        DataHandler.h
-        DataHandlerCPU.h
-        DataHandlerMapCPU.h
+        Handlers/DataHandler.h
+        Handlers/DataHandlerCPU.h
+        Handlers/DataHandlerMapCPU.h
         LinearOperator.h
         Expression.h
         ExpressionPredicates.h)
 
 # list all the code files of the module
 set(MODULE_SOURCES
-        DataDescriptor.cpp
-        RandomBlocksDescriptor.cpp
-        IdenticalBlocksDescriptor.cpp
-        PartitionDescriptor.cpp
+        Descriptors/DataDescriptor.cpp
+        Descriptors/VolumeDescriptor.cpp
+        Descriptors/RandomBlocksDescriptor.cpp
+        Descriptors/DescriptorUtils.cpp
+        Descriptors/IdenticalBlocksDescriptor.cpp
+        Descriptors/PartitionDescriptor.cpp
         DataContainer.cpp
-        DataHandlerCPU.cpp
-        DataHandlerMapCPU.cpp
+        Handlers/DataHandlerCPU.cpp
+        Handlers/DataHandlerMapCPU.cpp
         LinearOperator.cpp)
 
 if(${ELSA_CUDA_VECTOR})
     set(MODULE_HEADERS
         ${MODULE_HEADERS}
-        DataHandlerGPU.h
-        DataHandlerMapGPU.h)
+        Handlers/DataHandlerGPU.h
+        Handlers/DataHandlerMapGPU.h)
 
     set(MODULE_SOURCES
         ${MODULE_SOURCES}
-        DataHandlerGPU.cpp
-        DataHandlerMapGPU.cpp)
+        Handlers/DataHandlerGPU.cpp
+        Handlers/DataHandlerMapGPU.cpp)
 endif()
 
 # build the module library
@@ -62,12 +66,17 @@ endif()
 # link Quickvec for DataHandlerGPU
 if(ELSA_CUDA_VECTOR AND Quickvec_FOUND)
     target_link_libraries(${ELSA_MODULE_TARGET_NAME} PUBLIC Quickvec::quickvec)
+    target_compile_definitions(${ELSA_MODULE_TARGET_NAME} PUBLIC ELSA_ENABLE_CUDA_VECTOR)
 endif()
 
 target_include_directories(${ELSA_MODULE_TARGET_NAME}
         PUBLIC
         $<INSTALL_INTERFACE:include/elsa/${ELSA_MODULE_NAME}>
+        $<INSTALL_INTERFACE:include/elsa/${ELSA_MODULE_NAME}/Descriptors>
+        $<INSTALL_INTERFACE:include/elsa/${ELSA_MODULE_NAME}/Handlers>
         $<BUILD_INTERFACE:${CMAKE_CURRENT_SOURCE_DIR}>
+        $<BUILD_INTERFACE:${CMAKE_CURRENT_SOURCE_DIR}/Descriptors>
+        $<BUILD_INTERFACE:${CMAKE_CURRENT_SOURCE_DIR}/Handlers>
         )
 
 

elsa/core/DataDescriptor.cpp → elsa/core/Descriptors/DataDescriptor.cpp

@@ -53,6 +53,8 @@ namespace elsa
                 _numberOfCoefficientsPerDimension.head(i).prod();
     }
 
+    DataDescriptor::~DataDescriptor() {}
+
     index_t DataDescriptor::getNumberOfDimensions() const { return _numberOfDimensions; }
 
     index_t DataDescriptor::getNumberOfCoefficients() const
@@ -97,55 +99,6 @@ namespace elsa
         return coordinate;
     }
 
-    std::unique_ptr<DataDescriptor>
-        DataDescriptor::bestCommon(const std::vector<const DataDescriptor*>& descList)
-    {
-        if (descList.empty())
-            throw std::invalid_argument("DataDescriptor::bestCommon: descriptor list empty");
-
-        const auto& firstDesc = *descList[0];
-        auto coeffs = firstDesc.getNumberOfCoefficientsPerDimension();
-        auto size = firstDesc.getNumberOfCoefficients();
-        auto spacing = firstDesc.getSpacingPerDimension();
-
-        bool allSame =
-            std::all_of(descList.begin(), descList.end(),
-                        [&firstDesc](const DataDescriptor* d) { return *d == firstDesc; });
-        if (allSame)
-            return firstDesc.clone();
-
-        bool allSameCoeffs =
-            std::all_of(descList.begin(), descList.end(), [&coeffs](const DataDescriptor* d) {
-                return d->getNumberOfCoefficientsPerDimension().size() == coeffs.size()
-                       && d->getNumberOfCoefficientsPerDimension() == coeffs;
-            });
-
-        if (allSameCoeffs) {
-            bool allSameSpacing =
-                std::all_of(descList.begin(), descList.end(), [&spacing](const DataDescriptor* d) {
-                    return d->getSpacingPerDimension() == spacing;
-                });
-            if (allSameSpacing) {
-                return std::make_unique<DataDescriptor>(coeffs, spacing);
-            } else {
-                return std::make_unique<DataDescriptor>(coeffs);
-            }
-        }
-
-        bool allSameSize =
-            std::all_of(descList.begin(), descList.end(), [size](const DataDescriptor* d) {
-                return d->getNumberOfCoefficients() == size;
-            });
-
-        if (!allSameSize)
-            throw std::invalid_argument(
-                "DataDescriptor::bestCommon: descriptor sizes do not match");
-
-        return std::make_unique<DataDescriptor>(IndexVector_t::Constant(1, size));
-    }
-
-    DataDescriptor* DataDescriptor::cloneImpl() const { return new DataDescriptor(*this); }
-
     bool DataDescriptor::isEqual(const DataDescriptor& other) const
     {
         if (typeid(other) != typeid(*this))

elsa/core/DataDescriptor.h → elsa/core/Descriptors/DataDescriptor.h

@@ -9,15 +9,18 @@ namespace elsa
 {
 
     /**
-     * \brief Class representing metadata for linearized n-dimensional signal stored in memory
+     * \brief Base class for representing metadata for linearized n-dimensional signal stored in
+     * memory
      *
      * \author Matthias Wieczorek - initial code
      * \author Tobias Lasser - modularization, modernization
      * \author Maximilian Hornung - various enhancements
+     * \author David Frank - inheritance restructuring
+     *
+     * This class provides an interface for metadata about a signal that is stored in memory. This
+     * base class provides other descriptor subclasses with a fundamental interface to access the
+     * important parameters (i.e. dimensionality, size and spacing) of the metadata.
      *
-     * This class provides metadata about a signal that is stored in memory (typically a
-     * DataContainer). This signal can be n-dimensional, and will be stored in memory in a
-     * linearized fashion.
      */
     class DataDescriptor : public Cloneable<DataDescriptor>
     {
@@ -25,8 +28,8 @@ namespace elsa
         /// delete default constructor (having no metadata is invalid)
         DataDescriptor() = delete;
 
-        /// default destructor
-        ~DataDescriptor() override = default;
+        /// Pure virtual destructor
+        virtual ~DataDescriptor() = 0;
 
         /**
          * \brief Constructor for DataDescriptor, accepts dimension and size
@@ -90,35 +93,6 @@ namespace elsa
          */
         IndexVector_t getCoordinateFromIndex(index_t index) const;
 
-        /**
-         * \brief Finds the descriptor with the same number of coefficients as the descriptors in
-         * the list that retains as much information as possible
-         *
-         * \param[in] descriptorList a vector of plain pointers to DataDescriptor
-         *
-         * \return std::unique_ptr<DataDescriptor> the best common descriptor
-         *
-         * \throw std::invalid_argument if the vector is empty or the descriptors in the vector
-         * don't all have the same size
-         *
-         * If all descriptors are equal, a clone of the first descriptor in the list is returned.
-         * If all descriptors have a common base descriptor, that data descriptor is returned.
-         * If the base descriptors only differ in spacing, the base descriptor with a uniform
-         * spacing of 1 is returned.
-         * Otherwise, the linearized descriptor with a spacing of 1 is returned.
-         */
-        static std::unique_ptr<DataDescriptor>
-            bestCommon(const std::vector<const DataDescriptor*>& descriptorList);
-
-        /// convenience overload for invoking bestCommon() with a number of const DataDescriptor&
-        template <
-            typename... DescriptorType,
-            typename = std::enable_if_t<(std::is_base_of_v<DataDescriptor, DescriptorType> && ...)>>
-        static std::unique_ptr<DataDescriptor> bestCommon(const DescriptorType&... descriptors)
-        {
-            return bestCommon(std::vector{static_cast<const DataDescriptor*>(&descriptors)...});
-        }
-
     protected:
         /// Number of dimensions
         index_t _numberOfDimensions;
@@ -142,9 +116,6 @@ namespace elsa
         /// default move constructor, hidden from non-derived classes to prevent potential slicing
         DataDescriptor(DataDescriptor&&) = default;
 
-        /// implement the polymorphic clone operation
-        DataDescriptor* cloneImpl() const override;
-
         /// implement the polymorphic comparison operation
         bool isEqual(const DataDescriptor& other) const override;
     };

elsa/core/Descriptors/DescriptorUtils.cpp

+#include "DescriptorUtils.h"
+#include "DataDescriptor.h"
+#include "VolumeDescriptor.h"
+
+namespace elsa
+{
+    std::unique_ptr<DataDescriptor> bestCommon(const std::vector<const DataDescriptor*>& descList)
+    {
+        if (descList.empty())
+            throw std::invalid_argument("DataDescriptor::bestCommon: descriptor list empty");
+
+        const auto& firstDesc = *descList[0];
+        auto coeffs = firstDesc.getNumberOfCoefficientsPerDimension();
+        auto size = firstDesc.getNumberOfCoefficients();
+        auto spacing = firstDesc.getSpacingPerDimension();
+
+        bool allSame =
+            std::all_of(descList.begin(), descList.end(),
+                        [&firstDesc](const DataDescriptor* d) { return *d == firstDesc; });
+        if (allSame)
+            return firstDesc.clone();
+
+        bool allSameCoeffs =
+            std::all_of(descList.begin(), descList.end(), [&coeffs](const DataDescriptor* d) {
+                return d->getNumberOfCoefficientsPerDimension().size() == coeffs.size()
+                       && d->getNumberOfCoefficientsPerDimension() == coeffs;
+            });
+
+        if (allSameCoeffs) {
+            bool allSameSpacing =
+                std::all_of(descList.begin(), descList.end(), [&spacing](const DataDescriptor* d) {
+                    return d->getSpacingPerDimension() == spacing;
+                });
+            if (allSameSpacing) {
+                return std::make_unique<VolumeDescriptor>(coeffs, spacing);
+            } else {
+                return std::make_unique<VolumeDescriptor>(coeffs);
+            }
+        }
+
+        bool allSameSize =
+            std::all_of(descList.begin(), descList.end(), [size](const DataDescriptor* d) {
+                return d->getNumberOfCoefficients() == size;
+            });
+
+        if (!allSameSize)
+            throw std::invalid_argument(
+                "DataDescriptor::bestCommon: descriptor sizes do not match");
+
+        return std::make_unique<VolumeDescriptor>(IndexVector_t::Constant(1, size));
+    }
+} // namespace elsa
\ No newline at end of file

elsa/core/Descriptors/DescriptorUtils.h

+#pragma once
+
+#include "DataDescriptor.h"
+
+namespace elsa
+{
+    /**
+     * \brief Finds the descriptor with the same number of coefficients as the descriptors in
+     * the list that retains as much information as possible
+     *
+     * \param[in] descriptorList a vector of plain pointers to DataDescriptor
+     *
+     * \return std::unique_ptr<DataDescriptor> the best common descriptor
+     *
+     * \throw std::invalid_argument if the vector is empty or the descriptors in the vector
+     * don't all have the same size
+     *
+     * If all descriptors are equal, a clone of the first descriptor in the list is returned.
+     * If all descriptors have a common base descriptor, that data descriptor is returned.
+     * If the base descriptors only differ in spacing, the base descriptor with a uniform
+     * spacing of 1 is returned.
+     * Otherwise, the linearized descriptor with a spacing of 1 is returned.
+     */
+    std::unique_ptr<DataDescriptor>
+        bestCommon(const std::vector<const DataDescriptor*>& descriptorList);
+
+    /// convenience overload for invoking bestCommon() with a number of const DataDescriptor&
+    template <
+        typename... DescriptorType,
+        typename = std::enable_if_t<(std::is_base_of_v<DataDescriptor, DescriptorType> && ...)>>
+    std::unique_ptr<DataDescriptor> bestCommon(const DescriptorType&... descriptors)
+    {
+        return bestCommon(std::vector{static_cast<const DataDescriptor*>(&descriptors)...});
+    }
+} // namespace elsa
\ No newline at end of file

elsa/core/IdenticalBlocksDescriptor.cpp → elsa/core/Descriptors/IdenticalBlocksDescriptor.cpp

 #include "IdenticalBlocksDescriptor.h"
+#include "VolumeDescriptor.h"
 
 namespace elsa
 {
@@ -48,8 +49,8 @@ namespace elsa
         return true;
     }
 
-    DataDescriptor IdenticalBlocksDescriptor::initBase(index_t numberOfBlocks,
-                                                       const DataDescriptor& dataDescriptor)
+    VolumeDescriptor IdenticalBlocksDescriptor::initBase(index_t numberOfBlocks,
+                                                         const DataDescriptor& dataDescriptor)
     {
         if (numberOfBlocks < 1)
             throw std::invalid_argument(
@@ -63,6 +64,6 @@ namespace elsa
         numberOfCoeffs[numDim - 1] = numberOfBlocks;
         spacingOfCoeffs[numDim - 1] = 1;
 
-        return DataDescriptor(numberOfCoeffs, spacingOfCoeffs);
+        return VolumeDescriptor(numberOfCoeffs, spacingOfCoeffs);
     }
-} // namespace elsa
\ No newline at end of file
+} // namespace elsa

elsa/core/IdenticalBlocksDescriptor.h → elsa/core/Descriptors/IdenticalBlocksDescriptor.h

 #include "BlockDescriptor.h"
+#include "VolumeDescriptor.h"
 
 namespace elsa
 {
@@ -13,7 +14,7 @@ namespace elsa
      * for the indexing of the different blocks, and will always have a spacing of one and a number
      * of coefficients corresponding to the number of blocks.
      *
-     * This descriptor should be the prefferred choice when dealing with vector fields.
+     * This descriptor should be the preferred choice when dealing with vector fields.
      */
     class IdenticalBlocksDescriptor : public BlockDescriptor
     {
@@ -24,7 +25,7 @@ namespace elsa
          *
          *  \param[in] numberOfBlocks is the desired number of blocks
          *  \param[in] dataDescriptor is the descriptor that will be replicated numberOfBlocks
-         times
+         *  times
          * along a new dimension
          *
          *  \throw std::invalid_argument if numberOfBlocks is non-positive
@@ -61,6 +62,6 @@ namespace elsa
 
     private:
         /// generates the
-        DataDescriptor initBase(index_t numberOfBlocks, const DataDescriptor& dataDescriptor);
+        VolumeDescriptor initBase(index_t numberOfBlocks, const DataDescriptor& dataDescriptor);
     };
-} // namespace elsa
\ No newline at end of file
+} // namespace elsa

elsa/core/PartitionDescriptor.cpp → elsa/core/Descriptors/PartitionDescriptor.cpp

@@ -123,11 +123,11 @@ namespace elsa
         return _blockOffsets == otherBlock->_blockOffsets;
     }
 
-    std::unique_ptr<DataDescriptor>
+    std::unique_ptr<VolumeDescriptor>
         PartitionDescriptor::generateDescriptorOfPartition(index_t numberOfSlices) const
     {
         auto coeffsPerDim = getNumberOfCoefficientsPerDimension();
         coeffsPerDim[_numberOfDimensions - 1] = numberOfSlices;
-        return std::make_unique<DataDescriptor>(coeffsPerDim, getSpacingPerDimension());
+        return std::make_unique<VolumeDescriptor>(coeffsPerDim, getSpacingPerDimension());
     }
 } // namespace elsa

elsa/core/PartitionDescriptor.h → elsa/core/Descriptors/PartitionDescriptor.h

 #include "BlockDescriptor.h"
+#include "VolumeDescriptor.h"
+
 namespace elsa
 {
     /**
@@ -11,8 +13,8 @@ namespace elsa
      * slices of the original descriptor, taken along its last dimension. This also means that the
      * number of coefficients per block can only vary in the last dimension.
      *
-     * The PartitionDescriptor has the same number of coefficients and spacing per dimension as the
-     * original.
+     * The PartitionDescriptor has the same dimension, the same number of coefficients and spacing
+     * per dimension as the original.
      */
     class PartitionDescriptor : public BlockDescriptor
     {
@@ -85,6 +87,7 @@ namespace elsa
 
     private:
         /// generates the descriptor of a partition containing numberOfSlices slices
-        std::unique_ptr<DataDescriptor> generateDescriptorOfPartition(index_t numberOfSlices) const;
+        std::unique_ptr<VolumeDescriptor>
+            generateDescriptorOfPartition(index_t numberOfSlices) const;
     };
 } // namespace elsa

elsa/core/RandomBlocksDescriptor.cpp → elsa/core/Descriptors/RandomBlocksDescriptor.cpp

 #include "RandomBlocksDescriptor.h"
+#include "VolumeDescriptor.h"
 
 namespace elsa
 {
     RandomBlocksDescriptor::RandomBlocksDescriptor(
         const std::vector<std::unique_ptr<DataDescriptor>>& blockDescriptors)
-        : BlockDescriptor{DataDescriptor{determineSize(blockDescriptors)}},
+        : BlockDescriptor{VolumeDescriptor{determineSize(blockDescriptors)}},
           _blockDescriptors(0),
           _blockOffsets{blockDescriptors.size()}
     {
@@ -19,7 +20,7 @@ namespace elsa
 
     RandomBlocksDescriptor::RandomBlocksDescriptor(
         std::vector<std::unique_ptr<DataDescriptor>>&& blockDescriptors)
-        : BlockDescriptor{DataDescriptor{determineSize(blockDescriptors)}},
+        : BlockDescriptor{VolumeDescriptor{determineSize(blockDescriptors)}},
           _blockDescriptors{std::move(blockDescriptors)},
           _blockOffsets{_blockDescriptors.size()}
     {
@@ -90,4 +91,4 @@ namespace elsa
         return IndexVector_t::Constant(1, size);
     }
 
-} // namespace elsa
\ No newline at end of file
+} // namespace elsa

elsa/core/RandomBlocksDescriptor.h → elsa/core/Descriptors/RandomBlocksDescriptor.h

@@ -16,7 +16,9 @@ namespace elsa
      * There are no restrictions whatsoever imposed on the descriptors of different blocks.
      * Different blocks may even have different number of dimensions.
      *
-     * The full descriptor will always be one-dimensional, and with a spacing of one.
+     * The full descriptor will always be one-dimensional, and with a spacing of one. The size of it
+     * will be the sum of the sizes of all the descriptors, i.e. the sizes returned by
+     * DataDescriptor::getNumberOfCoefficients() for each descriptor in the list.
      */
     class RandomBlocksDescriptor : public BlockDescriptor
     {

elsa/core/Descriptors/VolumeDescriptor.cpp

+#include "VolumeDescriptor.h"
+
+#include <stdexcept>
+#include <algorithm>
+
+namespace elsa
+{
+    VolumeDescriptor::VolumeDescriptor(IndexVector_t numberOfCoefficientsPerDimension)
+        : DataDescriptor(numberOfCoefficientsPerDimension)
+    {
+    }
+
+    VolumeDescriptor::VolumeDescriptor(IndexVector_t numberOfCoefficientsPerDimension,
+                                       RealVector_t spacingPerDimension)
+        : DataDescriptor(numberOfCoefficientsPerDimension, spacingPerDimension)
+    {
+    }
+
+    VolumeDescriptor* VolumeDescriptor::cloneImpl() const
+    {
+        return new VolumeDescriptor(_numberOfCoefficientsPerDimension, _spacingPerDimension);
+    }
+
+    bool VolumeDescriptor::isEqual(const DataDescriptor& other) const
+    {
+        return DataDescriptor::isEqual(other);
+    }
+
+} // namespace elsa

elsa/core/Descriptors/VolumeDescriptor.h

+#pragma once
+
+#include "DataDescriptor.h"
+
+namespace elsa
+{
+
+    /**
+     * \brief Class representing metadata for linearized n-dimensional signal stored in memory
+     *
+     * \author Matthias Wieczorek - initial code
+     * \author Tobias Lasser - modularization, modernization
+     * \author Maximilian Hornung - various enhancements
+     * \author David Frank - inheritance restructuring
+     *
+     * This class provides metadata about a signal that is stored in memory (typically a
+     * DataContainer). This signal can be n-dimensional, and will be stored in memory in a
+     * linearized fashion.
+     */
+    class VolumeDescriptor : public DataDescriptor
+    {
+    public:
+        /// delete default constructor (having no metadata is invalid)
+        VolumeDescriptor() = delete;
+
+        /// default destructor
+        ~VolumeDescriptor() override = default;
+
+        /**
+         * \brief Constructor for DataDescriptor, accepts dimension and size
+         *
+         * \param[in] numberOfCoefficientsPerDimension vector containing the number of coefficients
+         * per dimension, (dimension is set implicitly from the size of the vector)
+         *
+         * \throw std::invalid_argument if any number of coefficients is non-positive
+         */
+        explicit VolumeDescriptor(IndexVector_t numberOfCoefficientsPerDimension);
+
+        /**
+         * \brief Constructor for DataDescriptor, accepts dimension, size and spacing
+         *
+         * \param[in] numberOfCoefficientsPerDimension vector containing the number of coefficients
+         * per dimension, (dimension is set implicitly from the size of the vector)
+         * \param[in] spacingPerDimension vector containing the spacing per dimension
+         *
+         * \throw std::invalid_argument if any number of coefficients is non-positive,
+         *        or sizes of numberOfCoefficientsPerDimension and spacingPerDimension do not match
+         */
+        explicit VolumeDescriptor(IndexVector_t numberOfCoefficientsPerDimension,
+                                  RealVector_t spacingPerDimension);
+
+    private:
+        /// implement the polymorphic clone operation
+        VolumeDescriptor* cloneImpl() const override;
+
+        /// implement the polymorphic comparison operation
+        bool isEqual(const DataDescriptor& other) const override;
+    };
+
+} // namespace elsa