diff --git a/src/ifcconvert/ColladaSerializer.cpp b/src/ifcconvert/ColladaSerializer.cpp
index 43fa842c96..3b9c573fab 100644
--- a/src/ifcconvert/ColladaSerializer.cpp
+++ b/src/ifcconvert/ColladaSerializer.cpp
@@ -208,13 +208,12 @@ void ColladaSerializer::ColladaExporter::ColladaMaterials::write() {
 	closeLibrary();
 }
 		
-void ColladaSerializer::ColladaExporter::startDocument() {
+void ColladaSerializer::ColladaExporter::startDocument(const std::string& unit_name, float unit_magnitude) {
 	stream.startDocument();
 
 	COLLADASW::Asset asset(&stream);
 	asset.getContributor().mAuthoringTool = std::string("IfcOpenShell ") + IFCOPENSHELL_VERSION;
-	// TODO: Get the appropriate unit from the IFC file.
-	asset.setUnit("meter", 1.0);
+	asset.setUnit(unit_name, unit_magnitude);
 	asset.setUpAxisType(COLLADASW::Asset::Z_UP);
 	asset.add();
 }
@@ -271,7 +270,7 @@ bool ColladaSerializer::ready() {
 }
 
 void ColladaSerializer::writeHeader() {
-	exporter.startDocument();
+	exporter.startDocument(unit_name, unit_magnitude);
 }
 
 void ColladaSerializer::writeTesselated(const IfcGeomObjects::IfcGeomObject* o) {
diff --git a/src/ifcconvert/ColladaSerializer.h b/src/ifcconvert/ColladaSerializer.h
index 60646202d5..7bb7f80e6d 100644
--- a/src/ifcconvert/ColladaSerializer.h
+++ b/src/ifcconvert/ColladaSerializer.h
@@ -135,11 +135,13 @@ private:
 		{}
 		std::vector<DeferredObject> deferreds;
 		virtual ~ColladaExporter() {}
-		void startDocument();
+		void startDocument(const std::string& unit_name, float unit_magnitude);
 		void writeTesselated(const std::string& guid, const std::string& name, const std::string& type, int obj_id, const std::vector<float>& matrix, const std::vector<float>& vertices, const std::vector<float>& normals, const std::vector<int>& indices, const std::vector<int>& material_ids, const std::vector<IfcGeomObjects::Material>& materials);
 		void endDocument();
 	};
 	ColladaExporter exporter;
+	std::string unit_name;
+	float unit_magnitude;
 public:
 	ColladaSerializer(const std::string& dae_filename)
 		: GeometrySerializer()
@@ -151,6 +153,10 @@ public:
 	void writeShapeModel(const IfcGeomObjects::IfcGeomShapeModelObject* o) {}
 	void finalize();
 	bool isTesselated() const { return true; }
+	void setUnitNameAndMagnitude(const std::string& name, float magnitude) {
+		unit_name = name;
+		unit_magnitude = magnitude;
+	}
 };
 
 #endif
diff --git a/src/ifcconvert/GeometrySerializer.h b/src/ifcconvert/GeometrySerializer.h
index 4524f8b681..c4895069a0 100644
--- a/src/ifcconvert/GeometrySerializer.h
+++ b/src/ifcconvert/GeometrySerializer.h
@@ -31,6 +31,7 @@ public:
 	virtual ~GeometrySerializer() {} 
 	virtual void writeTesselated(const IfcGeomObjects::IfcGeomObject* o) = 0;
 	virtual void writeShapeModel(const IfcGeomObjects::IfcGeomShapeModelObject* o) = 0;
+	virtual void setUnitNameAndMagnitude(const std::string& name, float magnitude) = 0;
 };
 
 #endif
\ No newline at end of file
diff --git a/src/ifcconvert/IfcConvert.cpp b/src/ifcconvert/IfcConvert.cpp
index 3917af1b7e..5ee64d0a07 100644
--- a/src/ifcconvert/IfcConvert.cpp
+++ b/src/ifcconvert/IfcConvert.cpp
@@ -69,6 +69,9 @@ std::string change_extension(const std::string& fn, const std::string& ext) {
 	}
 }
 
+static std::stringstream log_stream;
+void write_log();
+
 int main(int argc, char** argv) {
 	boost::program_options::options_description generic_options;
 	generic_options.add_options()
@@ -180,11 +183,13 @@ int main(int argc, char** argv) {
 		*c = tolower(*c);
 	}
 
+	Logger::SetOutput(&std::cout, &log_stream);
+
 	GeometrySerializer* serializer;
 	if (output_extension == ".obj") {
 		const std::string mtl_filename = output_filename.substr(0,output_filename.size()-3) + "mtl";
 		if (!use_world_coords) {
-			Logger::Message(Logger::LOG_WARNING, "Use world coords settings ignored for WaveFront OBJ files");
+			Logger::Message(Logger::LOG_NOTICE, "Using world coords when writing WaveFront OBJ files");
 			IfcGeomObjects::Settings(IfcGeomObjects::USE_WORLD_COORDS, true);
 		}
 		serializer = new WaveFrontOBJSerializer(output_filename, mtl_filename);
@@ -201,6 +206,7 @@ int main(int argc, char** argv) {
 		serializer = new IgesSerializer(output_filename);
 	} else {
 		Logger::Message(Logger::LOG_ERROR, "Unknown output filename extension");
+		write_log();
 		printUsage(generic_options, geom_options);
 		return 1;
 	}
@@ -209,24 +215,32 @@ int main(int argc, char** argv) {
 
 	if (!serializer->ready()) {
 		Logger::Message(Logger::LOG_ERROR, "Unable to open output file for writing");
+		write_log();
 		return 1;
 	}
 
-	serializer->writeHeader();
-
 	if (!serializer->isTesselated()) {
 		IfcGeomObjects::Settings(IfcGeomObjects::DISABLE_TRIANGULATION, true);
+		if (weld_vertices) {
+			Logger::Message(Logger::LOG_NOTICE, "Weld vertices setting ignored when writing STEP or IGES files");
+		}
 	}
 
-	// Stream for log messages, we don't want to interupt our new progress bar...
-	std::stringstream ss;
-
 	// Parse the file supplied in argv[1]. Returns true on succes.
-	if ( ! IfcGeomObjects::Init(input_filename,&std::cout,&ss) ) {
+	if ( ! IfcGeomObjects::Init(input_filename, &std::cout, &log_stream) ) {
 		Logger::Message(Logger::LOG_ERROR, "Unable to parse .ifc file or no geometrical entities found");
+		write_log();
 		return 1;
 	}
 
+	if (convert_back_units) {
+		serializer->setUnitNameAndMagnitude(IfcGeomObjects::GetUnitName(), IfcGeomObjects::GetUnitMagnitude());
+	} else {
+		serializer->setUnitNameAndMagnitude("METER", 1.0f);
+	}
+
+	serializer->writeHeader();
+
 	std::set<std::string> materials;
 
 	time_t start,end;
@@ -269,14 +283,17 @@ int main(int argc, char** argv) {
 
 	Logger::Status("\rDone creating geometry                                ");
 
-	// Writes the material settings, defined in Materials.h
-	std::string log = ss.str();
-	if (!log.empty()) {
-		std::cerr << std::endl << "Log:" << std::endl;
-		std::cerr << ss.str();
-	}
+	write_log();
 
 	time(&end);
 	int dif = (int) difftime (end,start);	
 	printf ("\nConversion took %d seconds\n", dif );
+}
+
+void write_log() {
+	std::string log = log_stream.str();
+	if (!log.empty()) {
+		std::cerr << std::endl << "Log:" << std::endl;
+		std::cerr << log << std::endl;
+	}
 }
\ No newline at end of file
diff --git a/src/ifcconvert/IgesSerializer.h b/src/ifcconvert/IgesSerializer.h
index 157fc67759..d18082c642 100644
--- a/src/ifcconvert/IgesSerializer.h
+++ b/src/ifcconvert/IgesSerializer.h
@@ -22,6 +22,7 @@
 
 #include <IGESControl_Controller.hxx>
 #include <IGESControl_Writer.hxx>
+#include <Interface_Static.hxx>
 
 #include "../ifcgeom/IfcGeomObjects.h"
 
@@ -42,6 +43,12 @@ public:
 	void finalize() {
 		writer.Write(out_filename.c_str());
 	}
+	void setUnitNameAndMagnitude(const std::string& name, float magnitude) {
+		const char* symbol = getSymbolForUnitMagnitude(magnitude);
+		if (symbol) {
+			Interface_Static::SetCVal("write.iges.unit", symbol);
+		}
+	}
 };
 
 #endif
\ No newline at end of file
diff --git a/src/ifcconvert/OpenCascadeBasedSerializer.cpp b/src/ifcconvert/OpenCascadeBasedSerializer.cpp
index fe8ca86176..0bf3f0c24b 100644
--- a/src/ifcconvert/OpenCascadeBasedSerializer.cpp
+++ b/src/ifcconvert/OpenCascadeBasedSerializer.cpp
@@ -62,3 +62,22 @@ void OpenCascadeBasedSerializer::writeShapeModel(const IfcGeomObjects::IfcGeomSh
 		writeShape(moved_shape);
 	}
 }
+
+#define RATHER_SMALL (1e-3)
+#define ALMOST_THE_SAME(a,b) (fabs(a-b) < RATHER_SMALL)
+
+const char* OpenCascadeBasedSerializer::getSymbolForUnitMagnitude(float mag) {
+	if (ALMOST_THE_SAME(mag, 0.001f)) {
+		return "MM";
+	} else if (ALMOST_THE_SAME(mag, 0.01f)) {
+		return "CM";
+	} else if (ALMOST_THE_SAME(mag, 1.0f)) {
+		return "M";
+	} else if (ALMOST_THE_SAME(mag, 0.3048f)) {
+		return "FT";
+	} else if (ALMOST_THE_SAME(mag, 0.0254f)) {
+		return "INCH";
+	} else {
+		return 0;
+	}
+}
diff --git a/src/ifcconvert/OpenCascadeBasedSerializer.h b/src/ifcconvert/OpenCascadeBasedSerializer.h
index 5087bc1023..15472363bd 100644
--- a/src/ifcconvert/OpenCascadeBasedSerializer.h
+++ b/src/ifcconvert/OpenCascadeBasedSerializer.h
@@ -27,6 +27,7 @@
 class OpenCascadeBasedSerializer : public GeometrySerializer {
 protected:
 	const std::string& out_filename;
+	const char* getSymbolForUnitMagnitude(float mag);
 public:
 	explicit OpenCascadeBasedSerializer(const std::string& out_filename)
 		: GeometrySerializer()
diff --git a/src/ifcconvert/StepSerializer.h b/src/ifcconvert/StepSerializer.h
index db5267af49..d0db600704 100644
--- a/src/ifcconvert/StepSerializer.h
+++ b/src/ifcconvert/StepSerializer.h
@@ -22,6 +22,7 @@
 
 #include <STEPControl_Controller.hxx>
 #include <STEPControl_Writer.hxx>
+#include <Interface_Static.hxx>
 
 #include "../ifcgeom/IfcGeomObjects.h"
 
@@ -37,10 +38,22 @@ public:
 	{}
 	virtual ~StepSerializer() {}
 	void writeShape(const TopoDS_Shape& shape) {
+		std::stringstream ss;
+		std::streambuf *sb = std::cout.rdbuf(ss.rdbuf());
 		writer.Transfer(shape, STEPControl_AsIs);
+		std::cout.rdbuf(sb);
 	}
 	void finalize() {
+		std::stringstream ss;
+		std::streambuf *sb = std::cout.rdbuf(ss.rdbuf());
 		writer.Write(out_filename.c_str());
+		std::cout.rdbuf(sb);
+	}
+	void setUnitNameAndMagnitude(const std::string& name, float magnitude) {
+		const char* symbol = getSymbolForUnitMagnitude(magnitude);
+		if (symbol) {
+			Interface_Static::SetCVal("write.step.unit", symbol);
+		}
 	}
 };
 
diff --git a/src/ifcconvert/WavefrontObjSerializer.h b/src/ifcconvert/WavefrontObjSerializer.h
index 6124c8d5c3..b31dcc1c94 100644
--- a/src/ifcconvert/WavefrontObjSerializer.h
+++ b/src/ifcconvert/WavefrontObjSerializer.h
@@ -49,6 +49,7 @@ public:
 	void writeShapeModel(const IfcGeomObjects::IfcGeomShapeModelObject* o) {}
 	void finalize() {}
 	bool isTesselated() const { return true; }
+	void setUnitNameAndMagnitude(const std::string& name, float magnitude) {}
 };
 
 #endif
\ No newline at end of file
diff --git a/src/ifcgeom/IfcGeomObjects.cpp b/src/ifcgeom/IfcGeomObjects.cpp
index 232bd29f0c..1e92d17d02 100644
--- a/src/ifcgeom/IfcGeomObjects.cpp
+++ b/src/ifcgeom/IfcGeomObjects.cpp
@@ -605,6 +605,9 @@ void IfcGeomObjects::InitPrecision() {
 	}
 }
 
+static std::string unit_name = "METER";
+static float unit_magnitude = 1.0f;
+
 void IfcGeomObjects::InitUnits() {
 	// Set default units, set length to meters, angles to undefined
 	IfcGeom::SetValue(IfcGeom::GV_LENGTH_UNIT,1.0);
@@ -631,11 +634,13 @@ void IfcGeomObjects::InitUnits() {
 	}
 	try {
 		for ( IfcUtil::IfcAbstractSelect::it it = units->begin(); it != units->end(); ++ it ) {
+			std::string current_unit_name = "";
 			const IfcUtil::IfcAbstractSelect::ptr base = *it;
 			Ifc2x3::IfcSIUnit::ptr unit = Ifc2x3::IfcSIUnit::ptr();
 			double value = 1.0f;
 			if ( base->is(Ifc2x3::Type::IfcConversionBasedUnit) ) {
 				const Ifc2x3::IfcConversionBasedUnit::ptr u = reinterpret_pointer_cast<IfcUtil::IfcAbstractSelect,Ifc2x3::IfcConversionBasedUnit>(base);
+				current_unit_name = u->Name();
 				const Ifc2x3::IfcMeasureWithUnit::ptr u2 = u->ConversionFactor();
 				Ifc2x3::IfcUnit u3 = u2->UnitComponent();
 				if ( u3->is(Ifc2x3::Type::IfcSIUnit) ) {
@@ -655,6 +660,14 @@ void IfcGeomObjects::InitUnits() {
 				Ifc2x3::IfcUnitEnum::IfcUnitEnum type = unit->UnitType();
 				if ( type == Ifc2x3::IfcUnitEnum::IfcUnit_LENGTHUNIT ) {
 					IfcGeom::SetValue(IfcGeom::GV_LENGTH_UNIT,value);
+					if (current_unit_name.empty()) {
+						if (unit->hasPrefix()) {
+							current_unit_name = Ifc2x3::IfcSIPrefix::ToString(unit->Prefix());
+						}
+						current_unit_name += Ifc2x3::IfcSIUnitName::ToString(unit->Name());
+					}
+					unit_magnitude = value;
+					unit_name = current_unit_name;
 				} else if ( type == Ifc2x3::IfcUnitEnum::IfcUnit_PLANEANGLEUNIT ) {
 					IfcGeom::SetValue(IfcGeom::GV_PLANEANGLE_UNIT,value);
 				}
@@ -740,6 +753,14 @@ int IfcGeomObjects::Progress() {
 	return 100 * done / total;
 }
 
+const std::string& IfcGeomObjects::GetUnitName() {
+	return unit_name;
+}
+
+const float IfcGeomObjects::GetUnitMagnitude() {
+	return unit_magnitude;
+}
+
 const std::string IfcGeomObjects::GetLog() {
 	return Logger::GetLog();
 }
diff --git a/src/ifcgeom/IfcGeomObjects.h b/src/ifcgeom/IfcGeomObjects.h
index 050ae2993d..a402b5e770 100644
--- a/src/ifcgeom/IfcGeomObjects.h
+++ b/src/ifcgeom/IfcGeomObjects.h
@@ -274,6 +274,9 @@ namespace IfcGeomObjects {
 	
 	bool Next();
 	int Progress();
+
+	const std::string& GetUnitName();
+	const float GetUnitMagnitude();
 	
 	const std::string GetLog();
 	IfcParse::IfcFile* GetFile();