diff --git a/code/Importer.h b/code/Importer.h
index 750b9bbbd..a35fb80d9 100644
--- a/code/Importer.h
+++ b/code/Importer.h
@@ -75,7 +75,7 @@ public:
     // typedefs for our four configuration maps.
     // We don't need more, so there is no need for a generic solution
     typedef std::map<KeyType, int> IntPropertyMap;
-    typedef std::map<KeyType, float> FloatPropertyMap;
+    typedef std::map<KeyType, ai_real> FloatPropertyMap;
     typedef std::map<KeyType, std::string> StringPropertyMap;
     typedef std::map<KeyType, aiMatrix4x4> MatrixPropertyMap;
 
diff --git a/code/SceneCombiner.cpp b/code/SceneCombiner.cpp
index b39adbf78..51541a34b 100644
--- a/code/SceneCombiner.cpp
+++ b/code/SceneCombiner.cpp
@@ -1132,7 +1132,7 @@ void SceneCombiner::Copy( aiAnimation** _dest, const aiAnimation* src )
 {
     ai_assert( NULL != _dest );
     ai_assert( NULL != src );
-    
+
     aiAnimation* dest = *_dest = new aiAnimation();
 
     // get a flat copy
@@ -1246,6 +1246,9 @@ void SceneCombiner::Copy (aiMetadata** _dest, const aiMetadata* src)
         case AI_FLOAT:
             out.mData = new float(*static_cast<float*>(in.mData));
             break;
+        case AI_DOUBLE:
+            out.mData = new double(*static_cast<double*>(in.mData));
+            break;
         case AI_AISTRING:
             out.mData = new aiString(*static_cast<aiString*>(in.mData));
             break;
diff --git a/code/SpatialSort.cpp b/code/SpatialSort.cpp
index c4e4ef2d5..ca6055e84 100644
--- a/code/SpatialSort.cpp
+++ b/code/SpatialSort.cpp
@@ -107,7 +107,7 @@ void SpatialSort::Append( const aiVector3D* pPositions, unsigned int pNumPositio
         const aiVector3D* vec   = reinterpret_cast<const aiVector3D*> (tempPointer + a * pElementOffset);
 
         // store position by index and distance
-        float distance = *vec * mPlaneNormal;
+        ai_real distance = *vec * mPlaneNormal;
         mPositions.push_back( Entry( a+initial, *vec, distance));
     }
 
@@ -120,10 +120,10 @@ void SpatialSort::Append( const aiVector3D* pPositions, unsigned int pNumPositio
 // ------------------------------------------------------------------------------------------------
 // Returns an iterator for all positions close to the given position.
 void SpatialSort::FindPositions( const aiVector3D& pPosition,
-    float pRadius, std::vector<unsigned int>& poResults) const
+    ai_real pRadius, std::vector<unsigned int>& poResults) const
 {
-    const float dist = pPosition * mPlaneNormal;
-    const float minDist = dist - pRadius, maxDist = dist + pRadius;
+    const ai_real dist = pPosition * mPlaneNormal;
+    const ai_real minDist = dist - pRadius, maxDist = dist + pRadius;
 
     // clear the array in this strange fashion because a simple clear() would also deallocate
     // the array which we want to avoid
@@ -160,7 +160,7 @@ void SpatialSort::FindPositions( const aiVector3D& pPosition,
     // Mow start iterating from there until the first position lays outside of the distance range.
     // Add all positions inside the distance range within the given radius to the result aray
     std::vector<Entry>::const_iterator it = mPositions.begin() + index;
-    const float pSquared = pRadius*pRadius;
+    const ai_real pSquared = pRadius*pRadius;
     while( it->mDistance < maxDist)
     {
         if( (it->mPosition - pPosition).SquareLength() < pSquared)
@@ -186,19 +186,19 @@ namespace {
 
     // --------------------------------------------------------------------------------------------
     // Converts the bit pattern of a floating-point number to its signed integer representation.
-    BinFloat ToBinary( const float & pValue) {
+    BinFloat ToBinary( const ai_real & pValue) {
 
         // If this assertion fails, signed int is not big enough to store a float on your platform.
         //  Please correct the declaration of BinFloat a few lines above - but do it in a portable,
         //  #ifdef'd manner!
-        static_assert( sizeof(BinFloat) >= sizeof(float), "sizeof(BinFloat) >= sizeof(float)");
+        static_assert( sizeof(BinFloat) >= sizeof(ai_real), "sizeof(BinFloat) >= sizeof(ai_real)");
 
         #if defined( _MSC_VER)
             // If this assertion fails, Visual C++ has finally moved to ILP64. This means that this
             //  code has just become legacy code! Find out the current value of _MSC_VER and modify
             //  the #if above so it evaluates false on the current and all upcoming VC versions (or
             //  on the current platform, if LP64 or LLP64 are still used on other platforms).
-            static_assert( sizeof(BinFloat) == sizeof(float), "sizeof(BinFloat) == sizeof(float)");
+            static_assert( sizeof(BinFloat) == sizeof(ai_real), "sizeof(BinFloat) == sizeof(ai_real)");
 
             // This works best on Visual C++, but other compilers have their problems with it.
             const BinFloat binValue = reinterpret_cast<BinFloat const &>(pValue);
@@ -206,7 +206,7 @@ namespace {
             // On many compilers, reinterpreting a float address as an integer causes aliasing
             // problems. This is an ugly but more or less safe way of doing it.
             union {
-                float       asFloat;
+                ai_real     asFloat;
                 BinFloat    asBin;
             } conversion;
             conversion.asBin    = 0; // zero empty space in case sizeof(BinFloat) > sizeof(float)
@@ -311,10 +311,10 @@ void SpatialSort::FindIdenticalPositions( const aiVector3D& pPosition,
 unsigned int SpatialSort::GenerateMappingTable(std::vector<unsigned int>& fill,float pRadius) const
 {
     fill.resize(mPositions.size(),UINT_MAX);
-    float dist, maxDist;
+    ai_real dist, maxDist;
 
     unsigned int t=0;
-    const float pSquared = pRadius*pRadius;
+    const ai_real pSquared = pRadius*pRadius;
     for (size_t i = 0; i < mPositions.size();) {
         dist = mPositions[i].mPosition * mPlaneNormal;
         maxDist = dist + pRadius;
@@ -339,4 +339,3 @@ unsigned int SpatialSort::GenerateMappingTable(std::vector<unsigned int>& fill,f
 #endif
     return t;
 }
-
diff --git a/code/SpatialSort.h b/code/SpatialSort.h
index b594fc6d1..367e0f6a6 100644
--- a/code/SpatialSort.h
+++ b/code/SpatialSort.h
@@ -117,7 +117,7 @@ public:
      * @param poResults The container to store the indices of the found positions.
      *   Will be emptied by the call so it may contain anything.
      * @return An iterator to iterate over all vertices in the given area.*/
-    void FindPositions( const aiVector3D& pPosition, float pRadius,
+    void FindPositions( const aiVector3D& pPosition, ai_real pRadius,
         std::vector<unsigned int>& poResults) const;
 
     // ------------------------------------------------------------------------------------
@@ -139,7 +139,7 @@ public:
      *   be counted in.
      *  @return Number of unique vertices (n).  */
     unsigned int GenerateMappingTable(std::vector<unsigned int>& fill,
-        float pRadius) const;
+        ai_real pRadius) const;
 
 protected:
     /** Normal of the sorting plane, normalized. The center is always at (0, 0, 0) */
@@ -151,10 +151,10 @@ protected:
     {
         unsigned int mIndex; ///< The vertex referred by this entry
         aiVector3D mPosition; ///< Position
-        float mDistance; ///< Distance of this vertex to the sorting plane
+        ai_real mDistance; ///< Distance of this vertex to the sorting plane
 
         Entry() { /** intentionally not initialized.*/ }
-        Entry( unsigned int pIndex, const aiVector3D& pPosition, float pDistance)
+        Entry( unsigned int pIndex, const aiVector3D& pPosition, ai_real pDistance)
             : mIndex( pIndex), mPosition( pPosition), mDistance( pDistance)
         {   }
 
diff --git a/code/Vertex.h b/code/Vertex.h
index 5e2cf6986..88840eab7 100644
--- a/code/Vertex.h
+++ b/code/Vertex.h
@@ -94,15 +94,15 @@ class Vertex
     friend Vertex operator + (const Vertex&,const Vertex&);
     friend Vertex operator - (const Vertex&,const Vertex&);
 
-//  friend Vertex operator + (const Vertex&,float);
-//  friend Vertex operator - (const Vertex&,float);
-    friend Vertex operator * (const Vertex&,float);
-    friend Vertex operator / (const Vertex&,float);
+//  friend Vertex operator + (const Vertex&,ai_real);
+//  friend Vertex operator - (const Vertex&,ai_real);
+    friend Vertex operator * (const Vertex&,ai_real);
+    friend Vertex operator / (const Vertex&,ai_real);
 
-//  friend Vertex operator + (float, const Vertex&);
-//  friend Vertex operator - (float, const Vertex&);
-    friend Vertex operator * (float, const Vertex&);
-//  friend Vertex operator / (float, const Vertex&);
+//  friend Vertex operator + (ai_real, const Vertex&);
+//  friend Vertex operator - (ai_real, const Vertex&);
+    friend Vertex operator * (ai_real, const Vertex&);
+//  friend Vertex operator / (ai_real, const Vertex&);
 
 public:
 
@@ -146,22 +146,22 @@ public:
 
 
 /*
-    Vertex& operator += (float v) {
+    Vertex& operator += (ai_real v) {
         *this = *this+v;
         return *this;
     }
 
-    Vertex& operator -= (float v) {
+    Vertex& operator -= (ai_real v) {
         *this = *this-v;
         return *this;
     }
 */
-    Vertex& operator *= (float v) {
+    Vertex& operator *= (ai_real v) {
         *this = *this*v;
         return *this;
     }
 
-    Vertex& operator /= (float v) {
+    Vertex& operator /= (ai_real v) {
         *this = *this/v;
         return *this;
     }
@@ -217,40 +217,40 @@ private:
 
     // ----------------------------------------------------------------------------
     /** This time binary arithmetics of v0 with a floating-point number */
-    template <template <typename, typename, typename> class op> static Vertex BinaryOp(const Vertex& v0, float f) {
+    template <template <typename, typename, typename> class op> static Vertex BinaryOp(const Vertex& v0, ai_real f) {
         // this is a heavy task for the compiler to optimize ... *pray*
 
         Vertex res;
-        res.position  = op<aiVector3D,float,aiVector3D>()(v0.position,f);
-        res.normal    = op<aiVector3D,float,aiVector3D>()(v0.normal,f);
-        res.tangent   = op<aiVector3D,float,aiVector3D>()(v0.tangent,f);
-        res.bitangent = op<aiVector3D,float,aiVector3D>()(v0.bitangent,f);
+        res.position  = op<aiVector3D,ai_real,aiVector3D>()(v0.position,f);
+        res.normal    = op<aiVector3D,ai_real,aiVector3D>()(v0.normal,f);
+        res.tangent   = op<aiVector3D,ai_real,aiVector3D>()(v0.tangent,f);
+        res.bitangent = op<aiVector3D,ai_real,aiVector3D>()(v0.bitangent,f);
 
         for (unsigned int i = 0; i < AI_MAX_NUMBER_OF_TEXTURECOORDS; ++i) {
-            res.texcoords[i] = op<aiVector3D,float,aiVector3D>()(v0.texcoords[i],f);
+            res.texcoords[i] = op<aiVector3D,ai_real,aiVector3D>()(v0.texcoords[i],f);
         }
         for (unsigned int i = 0; i < AI_MAX_NUMBER_OF_COLOR_SETS; ++i) {
-            res.colors[i] = op<aiColor4D,float,aiColor4D>()(v0.colors[i],f);
+            res.colors[i] = op<aiColor4D,ai_real,aiColor4D>()(v0.colors[i],f);
         }
         return res;
     }
 
     // ----------------------------------------------------------------------------
     /** This time binary arithmetics of v0 with a floating-point number */
-    template <template <typename, typename, typename> class op> static Vertex BinaryOp(float f, const Vertex& v0) {
+    template <template <typename, typename, typename> class op> static Vertex BinaryOp(ai_real f, const Vertex& v0) {
         // this is a heavy task for the compiler to optimize ... *pray*
 
         Vertex res;
-        res.position  = op<float,aiVector3D,aiVector3D>()(f,v0.position);
-        res.normal    = op<float,aiVector3D,aiVector3D>()(f,v0.normal);
-        res.tangent   = op<float,aiVector3D,aiVector3D>()(f,v0.tangent);
-        res.bitangent = op<float,aiVector3D,aiVector3D>()(f,v0.bitangent);
+        res.position  = op<ai_real,aiVector3D,aiVector3D>()(f,v0.position);
+        res.normal    = op<ai_real,aiVector3D,aiVector3D>()(f,v0.normal);
+        res.tangent   = op<ai_real,aiVector3D,aiVector3D>()(f,v0.tangent);
+        res.bitangent = op<ai_real,aiVector3D,aiVector3D>()(f,v0.bitangent);
 
         for (unsigned int i = 0; i < AI_MAX_NUMBER_OF_TEXTURECOORDS; ++i) {
-            res.texcoords[i] = op<float,aiVector3D,aiVector3D>()(f,v0.texcoords[i]);
+            res.texcoords[i] = op<ai_real,aiVector3D,aiVector3D>()(f,v0.texcoords[i]);
         }
         for (unsigned int i = 0; i < AI_MAX_NUMBER_OF_COLOR_SETS; ++i) {
-            res.colors[i] = op<float,aiColor4D,aiColor4D>()(f,v0.colors[i]);
+            res.colors[i] = op<ai_real,aiColor4D,aiColor4D>()(f,v0.colors[i]);
         }
         return res;
     }
@@ -279,41 +279,41 @@ AI_FORCE_INLINE Vertex operator - (const Vertex& v0,const Vertex& v1) {
 
 // ------------------------------------------------------------------------------------------------
 /*
-AI_FORCE_INLINE Vertex operator + (const Vertex& v0,float f) {
+AI_FORCE_INLINE Vertex operator + (const Vertex& v0,ai_real f) {
     return Vertex::BinaryOp<Intern::plus>(v0,f);
 }
 
-AI_FORCE_INLINE Vertex operator - (const Vertex& v0,float f) {
+AI_FORCE_INLINE Vertex operator - (const Vertex& v0,ai_real f) {
     return Vertex::BinaryOp<Intern::minus>(v0,f);
 }
 
 */
 
-AI_FORCE_INLINE Vertex operator * (const Vertex& v0,float f) {
+AI_FORCE_INLINE Vertex operator * (const Vertex& v0,ai_real f) {
     return Vertex::BinaryOp<Intern::multiplies>(v0,f);
 }
 
-AI_FORCE_INLINE Vertex operator / (const Vertex& v0,float f) {
+AI_FORCE_INLINE Vertex operator / (const Vertex& v0,ai_real f) {
     return Vertex::BinaryOp<Intern::multiplies>(v0,1.f/f);
 }
 
 // ------------------------------------------------------------------------------------------------
 /*
-AI_FORCE_INLINE Vertex operator + (float f,const Vertex& v0) {
+AI_FORCE_INLINE Vertex operator + (ai_real f,const Vertex& v0) {
     return Vertex::BinaryOp<Intern::plus>(f,v0);
 }
 
-AI_FORCE_INLINE Vertex operator - (float f,const Vertex& v0) {
+AI_FORCE_INLINE Vertex operator - (ai_real f,const Vertex& v0) {
     return Vertex::BinaryOp<Intern::minus>(f,v0);
 }
 */
 
-AI_FORCE_INLINE Vertex operator * (float f,const Vertex& v0) {
+AI_FORCE_INLINE Vertex operator * (ai_real f,const Vertex& v0) {
     return Vertex::BinaryOp<Intern::multiplies>(f,v0);
 }
 
 /*
-AI_FORCE_INLINE Vertex operator / (float f,const Vertex& v0) {
+AI_FORCE_INLINE Vertex operator / (ai_real f,const Vertex& v0) {
     return Vertex::BinaryOp<Intern::divides>(f,v0);
 }
 */
diff --git a/code/qnan.h b/code/qnan.h
index 02412bf21..80d6229f9 100644
--- a/code/qnan.h
+++ b/code/qnan.h
@@ -68,7 +68,21 @@ union _IEEESingle
         uint32_t Exp  : 8;
         uint32_t Sign : 1;
     } IEEE;
-} ;
+};
+
+// ---------------------------------------------------------------------------
+/** Data structure to represent the bit pattern of a 64 Bit
+ *         IEEE 754 floating-point number. */
+union _IEEEDouble
+{
+    double Double;
+    struct
+    {
+        uint64_t Frac : 52;
+        uint64_t Exp  : 11;
+        uint64_t Sign : 1;
+    } IEEE;
+};
 
 // ---------------------------------------------------------------------------
 /** Check whether a given float is qNaN.
@@ -87,11 +101,19 @@ AI_FORCE_INLINE bool is_qnan(float in)
 }
 
 // ---------------------------------------------------------------------------
-/** Check whether a float is NOT qNaN.
+/** Check whether a given double is qNaN.
  *  @param in Input value */
-AI_FORCE_INLINE bool is_not_qnan(float in)
+AI_FORCE_INLINE bool is_qnan(double in)
 {
-    return !is_qnan(in);
+    // the straightforward solution does not work:
+    //   return (in != in);
+    // compiler generates code like this
+    //   load <in> to <register-with-different-width>
+    //   compare <register-with-different-width> against <in>
+
+    // FIXME: Use <float> stuff instead? I think fpclassify needs C99
+    return (reinterpret_cast<_IEEEDouble*>(&in)->IEEE.Exp == (1u << 11)-1 &&
+        reinterpret_cast<_IEEEDouble*>(&in)->IEEE.Frac);
 }
 
 // ---------------------------------------------------------------------------
@@ -105,10 +127,29 @@ AI_FORCE_INLINE bool is_special_float(float in)
 }
 
 // ---------------------------------------------------------------------------
-/** @brief Get a fresh qnan.  */
-AI_FORCE_INLINE float get_qnan()
+/** @brief check whether a double is either NaN or (+/-) INF.
+ *
+ *  Denorms return false, they're treated like normal values.
+ *  @param in Input value */
+AI_FORCE_INLINE bool is_special_float(double in)
 {
-    return std::numeric_limits<float>::quiet_NaN();
+    return (reinterpret_cast<_IEEEDouble*>(&in)->IEEE.Exp == (1u << 11)-1);
+}
+
+// ---------------------------------------------------------------------------
+/** Check whether a float is NOT qNaN.
+ *  @param in Input value */
+template<class TReal>
+AI_FORCE_INLINE bool is_not_qnan(TReal in)
+{
+    return !is_qnan(in);
+}
+
+// ---------------------------------------------------------------------------
+/** @brief Get a fresh qnan.  */
+AI_FORCE_INLINE ai_real get_qnan()
+{
+    return std::numeric_limits<ai_real>::quiet_NaN();
 }
 
 #endif // !! AI_QNAN_H_INCLUDED
diff --git a/include/assimp/Exporter.hpp b/include/assimp/Exporter.hpp
index 18f5fb744..193d07f66 100644
--- a/include/assimp/Exporter.hpp
+++ b/include/assimp/Exporter.hpp
@@ -330,7 +330,7 @@ public:
     // typedefs for our four configuration maps.
     // We don't need more, so there is no need for a generic solution
     typedef std::map<KeyType, int> IntPropertyMap;
-    typedef std::map<KeyType, float> FloatPropertyMap;
+    typedef std::map<KeyType, ai_real> FloatPropertyMap;
     typedef std::map<KeyType, std::string> StringPropertyMap;
     typedef std::map<KeyType, aiMatrix4x4> MatrixPropertyMap;
 
@@ -380,7 +380,7 @@ public:
     /** Set a floating-point configuration property.
      * @see SetPropertyInteger()
      */
-    bool SetPropertyFloat(const char* szName, float fValue);
+    bool SetPropertyFloat(const char* szName, ai_real fValue);
 
     // -------------------------------------------------------------------
     /** Set a string configuration property.
@@ -425,8 +425,8 @@ public:
     /** Get a floating-point configuration property
      * @see GetPropertyInteger()
      */
-    float GetPropertyFloat(const char* szName,
-        float fErrorReturn = 10e10f) const;
+    ai_real GetPropertyFloat(const char* szName,
+        ai_real fErrorReturn = 10e10f) const;
 
     // -------------------------------------------------------------------
     /** Get a string configuration property
diff --git a/include/assimp/anim.h b/include/assimp/anim.h
index ea70cc170..e2961a67c 100644
--- a/include/assimp/anim.h
+++ b/include/assimp/anim.h
@@ -421,7 +421,7 @@ struct Interpolator
      *  The interpolation algorithm depends on the type of the operands.
      *  aiQuaternion's and aiQuatKey's SLERP, the rest does a simple
      *  linear interpolation. */
-    void operator () (T& out,const T& a, const T& b, float d) const {
+    void operator () (T& out,const T& a, const T& b, ai_real d) const {
         out = a + (b-a)*d;
     }
 }; // ! Interpolator <T>
@@ -431,7 +431,7 @@ struct Interpolator
 template <>
 struct Interpolator <aiQuaternion>  {
     void operator () (aiQuaternion& out,const aiQuaternion& a,
-        const aiQuaternion& b, float d) const
+        const aiQuaternion& b, ai_real d) const
     {
         aiQuaternion::Interpolate(out,a,b,d);
     }
@@ -440,7 +440,7 @@ struct Interpolator <aiQuaternion>  {
 template <>
 struct Interpolator <unsigned int>  {
     void operator () (unsigned int& out,unsigned int a,
-        unsigned int b, float d) const
+        unsigned int b, ai_real d) const
     {
         out = d>0.5f ? b : a;
     }
@@ -449,7 +449,7 @@ struct Interpolator <unsigned int>  {
 template <>
 struct Interpolator  <aiVectorKey>  {
     void operator () (aiVector3D& out,const aiVectorKey& a,
-        const aiVectorKey& b, float d) const
+        const aiVectorKey& b, ai_real d) const
     {
         Interpolator<aiVector3D> ipl;
         ipl(out,a.mValue,b.mValue,d);
@@ -459,7 +459,7 @@ struct Interpolator  <aiVectorKey>  {
 template <>
 struct Interpolator <aiQuatKey>     {
     void operator () (aiQuaternion& out, const aiQuatKey& a,
-        const aiQuatKey& b, float d) const
+        const aiQuatKey& b, ai_real d) const
     {
         Interpolator<aiQuaternion> ipl;
         ipl(out,a.mValue,b.mValue,d);
@@ -469,7 +469,7 @@ struct Interpolator <aiQuatKey>     {
 template <>
 struct Interpolator <aiMeshKey>     {
     void operator () (unsigned int& out, const aiMeshKey& a,
-        const aiMeshKey& b, float d) const
+        const aiMeshKey& b, ai_real d) const
     {
         Interpolator<unsigned int> ipl;
         ipl(out,a.mValue,b.mValue,d);
diff --git a/include/assimp/color4.h b/include/assimp/color4.h
index 8371cdeeb..6cd6a35b3 100644
--- a/include/assimp/color4.h
+++ b/include/assimp/color4.h
@@ -46,6 +46,7 @@ OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
 #define AI_COLOR4D_H_INC
 
 #include "./Compiler/pushpack1.h"
+#include "defs.h"
 
 #ifdef __cplusplus
 
@@ -90,12 +91,12 @@ public:
     TReal r, g, b, a;
 } PACK_STRUCT;  // !struct aiColor4D
 
-typedef aiColor4t<float> aiColor4D;
+typedef aiColor4t<ai_real> aiColor4D;
 
 #else
 
 struct aiColor4D {
-    float r, g, b, a;
+    ai_real r, g, b, a;
 } PACK_STRUCT;
 
 #endif // __cplusplus
diff --git a/include/assimp/defs.h b/include/assimp/defs.h
index 5cc431787..d23b391e1 100644
--- a/include/assimp/defs.h
+++ b/include/assimp/defs.h
@@ -242,10 +242,6 @@ OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
 #define AI_MATH_TWO_PI_F    (AI_MATH_PI_F * 2.0f)
 #define AI_MATH_HALF_PI_F   (AI_MATH_PI_F * 0.5f)
 
-/* Tiny macro to convert from radians to degrees and back */
-#define AI_DEG_TO_RAD(x) ((x)*0.0174532925f)
-#define AI_RAD_TO_DEG(x) ((x)*57.2957795f)
-
 /* Support for big-endian builds */
 #if defined(__BYTE_ORDER__)
 #   if (__BYTE_ORDER__ == __ORDER_BIG_ENDIAN__)
@@ -269,5 +265,16 @@ OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
  */
 #define AI_MAX_ALLOC(type) ((256U * 1024 * 1024) / sizeof(type))
 
+#ifdef AI_DOUBLE_PRECISION
+    typedef double ai_real;
+    /* Tiny macro to convert from radians to degrees and back */
+    #define AI_DEG_TO_RAD(x) ((x)*0.0174532925)
+    #define AI_RAD_TO_DEG(x) ((x)*57.2957795)
+#else
+    typedef float ai_real;
+    /* Tiny macro to convert from radians to degrees and back */
+    #define AI_DEG_TO_RAD(x) ((x)*0.0174532925f)
+    #define AI_RAD_TO_DEG(x) ((x)*57.2957795f)
+#endif // AI_SINGLEPRECISION
 
 #endif // !! AI_DEFINES_H_INC
diff --git a/include/assimp/material.h b/include/assimp/material.h
index def0e819b..09cc07ab4 100644
--- a/include/assimp/material.h
+++ b/include/assimp/material.h
@@ -477,13 +477,14 @@ struct aiUVTransform
      *  rotation center is 0.5f|0.5f. The default value
      *  0.f.
      */
-    float mRotation;
+    ai_real mRotation;
 
 
 #ifdef __cplusplus
     aiUVTransform()
-        :   mScaling    (1.f,1.f)
-        ,   mRotation   (0.f)
+        :   mTranslation (0.0,0.0)
+        ,   mScaling    (1.0,1.0)
+        ,   mRotation   (0.0)
     {
         // nothing to be done here ...
     }
diff --git a/include/assimp/matrix3x3.h b/include/assimp/matrix3x3.h
index 544d20b49..f6c151aa5 100644
--- a/include/assimp/matrix3x3.h
+++ b/include/assimp/matrix3x3.h
@@ -47,6 +47,7 @@ OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
 #define AI_MATRIX3X3_H_INC
 
 #include "./Compiler/pushpack1.h"
+#include "defs.h"
 
 #ifdef __cplusplus
 
@@ -166,14 +167,14 @@ public:
     TReal c1, c2, c3;
 } PACK_STRUCT;
 
-typedef aiMatrix3x3t<float> aiMatrix3x3;
+typedef aiMatrix3x3t<ai_real> aiMatrix3x3;
 
 #else
 
 struct aiMatrix3x3 {
-    float a1, a2, a3;
-    float b1, b2, b3;
-    float c1, c2, c3;
+    ai_real a1, a2, a3;
+    ai_real b1, b2, b3;
+    ai_real c1, c2, c3;
 } PACK_STRUCT;
 
 #endif // __cplusplus
diff --git a/include/assimp/matrix4x4.h b/include/assimp/matrix4x4.h
index 368e77cc6..b32ac7376 100644
--- a/include/assimp/matrix4x4.h
+++ b/include/assimp/matrix4x4.h
@@ -47,6 +47,7 @@ OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
 
 #include "vector3.h"
 #include "./Compiler/pushpack1.h"
+#include "defs.h"
 
 #ifdef __cplusplus
 
@@ -229,15 +230,15 @@ public:
     TReal d1, d2, d3, d4;
 } PACK_STRUCT;
 
-typedef aiMatrix4x4t<float> aiMatrix4x4;
+typedef aiMatrix4x4t<ai_real> aiMatrix4x4;
 
 #else
 
 struct aiMatrix4x4 {
-    float a1, a2, a3, a4;
-    float b1, b2, b3, b4;
-    float c1, c2, c3, c4;
-    float d1, d2, d3, d4;
+    ai_real a1, a2, a3, a4;
+    ai_real b1, b2, b3, b4;
+    ai_real c1, c2, c3, c4;
+    ai_real d1, d2, d3, d4;
 } PACK_STRUCT;
 
 
diff --git a/include/assimp/metadata.h b/include/assimp/metadata.h
index 5ed8f9f9b..258bf329c 100644
--- a/include/assimp/metadata.h
+++ b/include/assimp/metadata.h
@@ -68,8 +68,9 @@ typedef enum aiMetadataType
     AI_INT = 1,
     AI_UINT64 = 2,
     AI_FLOAT = 3,
-    AI_AISTRING = 4,
-    AI_AIVECTOR3D = 5,
+    AI_DOUBLE = 4,
+    AI_AISTRING = 5,
+    AI_AIVECTOR3D = 6,
 
 #ifndef SWIG
     FORCE_32BIT = INT_MAX
@@ -108,6 +109,7 @@ inline aiMetadataType GetAiType( bool ) { return AI_BOOL; }
 inline aiMetadataType GetAiType( int ) { return AI_INT; }
 inline aiMetadataType GetAiType( uint64_t ) { return AI_UINT64; }
 inline aiMetadataType GetAiType( float ) { return AI_FLOAT; }
+inline aiMetadataType GetAiType( double ) { return AI_DOUBLE; }
 inline aiMetadataType GetAiType( aiString ) { return AI_AISTRING; }
 inline aiMetadataType GetAiType( aiVector3D ) { return AI_AIVECTOR3D; }
 
@@ -172,6 +174,9 @@ struct aiMetadata
                 case AI_FLOAT:
                     delete static_cast<float*>(data);
                     break;
+                case AI_DOUBLE:
+                    delete static_cast<double*>(data);
+                    break;
                 case AI_AISTRING:
                     delete static_cast<aiString*>(data);
                     break;
@@ -248,5 +253,3 @@ struct aiMetadata
 };
 
 #endif // AI_METADATA_H_INC
-
-
diff --git a/include/assimp/quaternion.h b/include/assimp/quaternion.h
index edf442d62..fdc4d266b 100644
--- a/include/assimp/quaternion.h
+++ b/include/assimp/quaternion.h
@@ -47,6 +47,8 @@ OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
 
 #ifdef __cplusplus
 
+#include "defs.h"
+
 template <typename TReal> class aiVector3t;
 template <typename TReal> class aiMatrix3x3t;
 
@@ -113,12 +115,12 @@ public:
     TReal w, x, y, z;
 } ;
 
-typedef aiQuaterniont<float> aiQuaternion;
+typedef aiQuaterniont<ai_real> aiQuaternion;
 
 #else
 
 struct aiQuaternion {
-    float w, x, y, z;
+    ai_real w, x, y, z;
 };
 
 #endif
diff --git a/include/assimp/types.h b/include/assimp/types.h
index cdffce841..175675453 100644
--- a/include/assimp/types.h
+++ b/include/assimp/types.h
@@ -124,7 +124,7 @@ struct aiPlane
 {
 #ifdef __cplusplus
     aiPlane () : a(0.f), b(0.f), c(0.f), d(0.f) {}
-    aiPlane (float _a, float _b, float _c, float _d)
+    aiPlane (ai_real _a, ai_real _b, ai_real _c, ai_real _d)
         : a(_a), b(_b), c(_c), d(_d) {}
 
     aiPlane (const aiPlane& o) : a(o.a), b(o.b), c(o.c), d(o.d) {}
@@ -132,7 +132,7 @@ struct aiPlane
 #endif // !__cplusplus
 
     //! Plane equation
-    float a,b,c,d;
+    ai_real a,b,c,d;
 } PACK_STRUCT; // !struct aiPlane
 
 // ----------------------------------------------------------------------------------
@@ -160,8 +160,8 @@ struct aiColor3D
 {
 #ifdef __cplusplus
     aiColor3D () : r(0.0f), g(0.0f), b(0.0f) {}
-    aiColor3D (float _r, float _g, float _b) : r(_r), g(_g), b(_b) {}
-    explicit aiColor3D (float _r) : r(_r), g(_r), b(_r) {}
+    aiColor3D (ai_real _r, ai_real _g, ai_real _b) : r(_r), g(_g), b(_b) {}
+    explicit aiColor3D (ai_real _r) : r(_r), g(_r), b(_r) {}
     aiColor3D (const aiColor3D& o) : r(o.r), g(o.g), b(o.b) {}
 
     /** Component-wise comparison */
@@ -200,30 +200,30 @@ struct aiColor3D
     }
 
     /** Multiply with a scalar */
-    aiColor3D operator*(float f) const {
+    aiColor3D operator*(ai_real f) const {
         return aiColor3D(r*f,g*f,b*f);
     }
 
     /** Access a specific color component */
-    float operator[](unsigned int i) const {
+    ai_real operator[](unsigned int i) const {
         return *(&r + i);
     }
 
     /** Access a specific color component */
-    float& operator[](unsigned int i) {
+    ai_real& operator[](unsigned int i) {
         return *(&r + i);
     }
 
     /** Check whether a color is black */
     bool IsBlack() const {
-        static const float epsilon = 10e-3f;
+        static const ai_real epsilon = 10e-3;
         return std::fabs( r ) < epsilon && std::fabs( g ) < epsilon && std::fabs( b ) < epsilon;
     }
 
 #endif // !__cplusplus
 
     //! Red, green and blue color values
-    float r, g, b;
+    ai_real r, g, b;
 } PACK_STRUCT;  // !struct aiColor3D
 #include "./Compiler/poppack1.h"
 
diff --git a/include/assimp/vector2.h b/include/assimp/vector2.h
index a664cbecb..4122273c5 100644
--- a/include/assimp/vector2.h
+++ b/include/assimp/vector2.h
@@ -52,6 +52,7 @@ OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
 #endif
 
 #include "./Compiler/pushpack1.h"
+#include "defs.h"
 
 // ----------------------------------------------------------------------------------
 /** Represents a two-dimensional vector.
@@ -99,12 +100,12 @@ public:
     TReal x, y;
 } PACK_STRUCT;
 
-typedef aiVector2t<float> aiVector2D;
+typedef aiVector2t<ai_real> aiVector2D;
 
 #else
 
 struct aiVector2D {
-    float x, y;
+    ai_real x, y;
 };
 
 #endif // __cplusplus
diff --git a/include/assimp/vector3.h b/include/assimp/vector3.h
index 45571f84b..e3a3179f7 100644
--- a/include/assimp/vector3.h
+++ b/include/assimp/vector3.h
@@ -52,6 +52,7 @@ OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
 #endif
 
 #include "./Compiler/pushpack1.h"
+#include "defs.h"
 
 #ifdef __cplusplus
 
@@ -130,12 +131,12 @@ public:
 } PACK_STRUCT;
 
 
-typedef aiVector3t<float> aiVector3D;
+typedef aiVector3t<ai_real> aiVector3D;
 
 #else
 
 struct aiVector3D {
-    float x, y, z;
+    ai_real x, y, z;
 } PACK_STRUCT;
 
 #endif // __cplusplus