Handle missing or invalid unit and precision information more gracefully during IfcGeomObject initialization

src/ifcgeom/IfcGeomObjects.cpp

@@ -598,6 +598,9 @@ double UnitPrefixToValue( IfcSchema::IfcSIPrefix::IfcSIPrefix v ) {
 }
 
 void IfcGeomObjects::InitPrecision() {
+	IfcGeom::SetValue(IfcGeom::GV_PRECISION, 0.00001);
+
+	try {
 		IfcSchema::IfcGeometricRepresentationContext::list rep_contexts = ifc_file->EntitiesByType<IfcSchema::IfcGeometricRepresentationContext>();
 		// Currently, IfcGeometricRepresentationContext aren't used as much as they should be
 		// in the evaluation of shape representations, hence, we try to find the one with the
@@ -621,6 +624,11 @@ void IfcGeomObjects::InitPrecision() {
 		if (any_precision_encountered) {
 			IfcGeom::SetValue(IfcGeom::GV_PRECISION, lowest_precision_encountered);
 		}
+	} catch (const IfcParse::IfcException& ex) {
+		std::stringstream ss;
+		ss << "Failed to determine precision value '" << ex.what() << "'";
+		Logger::Message(Logger::LOG_ERROR, ss.str());
+	}
 }
 
 static std::string unit_name = "METER";
@@ -633,10 +641,13 @@ void IfcGeomObjects::InitUnits() {
 	
 	IfcSchema::IfcUnitAssignment::list unit_assignments = ifc_file->EntitiesByType<IfcSchema::IfcUnitAssignment>();
 	IfcUtil::IfcAbstractSelect::list units = IfcUtil::IfcAbstractSelect::list();
+	try {
 		if ( unit_assignments->Size() ) {
 			IfcSchema::IfcUnitAssignment::ptr unit_assignment = *unit_assignments->begin();
 			units = unit_assignment->Units();
 		}
+	} catch (const IfcParse::IfcException&) {}
+
 	if (!units) {
 		// No units eh... Since tolerances and deflection are specified internally in meters
 		// we will try to find another indication of the model size.
@@ -644,12 +655,18 @@ void IfcGeomObjects::InitUnits() {
 		if ( ! extrusions->Size() ) return;
 		double max_height = -1.0f;
 		for ( IfcSchema::IfcExtrudedAreaSolid::it it = extrusions->begin(); it != extrusions->end(); ++ it ) {
+			try {
 				const double depth = (*it)->Depth();
 				if ( depth > max_height ) max_height = depth;
+			} catch (const IfcParse::IfcException&) {}
+		}
+		if ( max_height > 100.0f ) {
+			IfcGeom::SetValue(IfcGeom::GV_LENGTH_UNIT,0.001);
+			Logger::Message(Logger::LOG_NOTICE, "Guessed length unit to be in millimeters based on extrusion depth");
 		}
-		if ( max_height > 100.0f ) IfcGeom::SetValue(IfcGeom::GV_LENGTH_UNIT,0.001);
 		return;
 	}
+
 	try {
 		for ( IfcUtil::IfcAbstractSelect::it it = units->begin(); it != units->end(); ++ it ) {
 			std::string current_unit_name = "";
@@ -691,8 +708,10 @@ void IfcGeomObjects::InitUnits() {
 				}
 			}
 		}
-	} catch ( IfcParse::IfcException ex ) {
+	} catch (const IfcParse::IfcException& ex) {
-		Logger::Message(Logger::LOG_ERROR,ex.what());
+		std::stringstream ss;
+		ss << "Failed to determine unit information '" << ex.what() << "'";
+		Logger::Message(Logger::LOG_ERROR, ss.str());
 	}
 }