diff --git a/floorplan/3D/FloorplanMesh.h b/floorplan/3D/FloorplanMesh.h
index d80e8dc..78826fa 100644
--- a/floorplan/3D/FloorplanMesh.h
+++ b/floorplan/3D/FloorplanMesh.h
@@ -123,7 +123,7 @@ namespace Floorplan3D {
 			// write material file
 			for (size_t idx = 0; idx < mats.size(); ++idx) {
 				const Material& mat = mats[idx];
-				res.mtl += "newmtl mat_" + std::to_string(idx) + "\n";
+				res.mtl += "newmtl mat_" + mat.name + "\n";
 				res.mtl += "Ka 0.000 0.000 0.000 \n";								// ambient
 				res.mtl += "Kd " + std::to_string(mat.r/255.0f) + " " + std::to_string(mat.g/255.0f) + " " + std::to_string(mat.b/255.0f) + "\n";
 				res.mtl += "Ks 0.000 0.000 0.000 \n";
@@ -166,7 +166,7 @@ namespace Floorplan3D {
 				res.obj += "o elem_" + std::to_string(++nObjs) + "\n";
 
 				// group's material
-				res.obj += "usemtl mat_" + std::to_string(getMaterial(o)) + "\n";
+				res.obj += "usemtl mat_" + getMaterial(o).name + "\n";
 
 				// write the group's faces
 				for (size_t i = 0; i < o.triangles.size(); ++i) {
@@ -227,7 +227,7 @@ namespace Floorplan3D {
 			}
 
 			for (const Obstacle3D& obs : elements) {
-				const int matIdx = getMaterial(obs);
+				const int matIdx = getMaterialIdx(obs);
 				const Material& mat = mats[matIdx];
 				for (const Triangle3& tria : obs.triangles) {
 					const Point3 n = cross(tria.p2-tria.p1, tria.p3-tria.p1).normalized();
@@ -253,7 +253,10 @@ namespace Floorplan3D {
 
 		struct Material {
 			int r, g, b, a;
+			std::string name;
 			Material(int r, int g, int b, int a) : r(r), g(g), b(b), a(a) {;}
+
+			Material(int r, int g, int b, int a, const std::string& name) : r(r), g(g), b(b), a(a), name(name) {;}
 		};
 
 
@@ -282,29 +285,31 @@ namespace Floorplan3D {
 
 		std::vector<Material> mats = {
 
-		    Material(255,0,0,255),		// error
+			Material(255,0,0,255    , "error"),            // error
 
-		    Material(0,128,0,255),		// ground outdoor
-		    Material(64,64,64,255),		// ground outdoor
-		    Material(105,105,105,255),	// stair
-		    Material(220,220,220,255),	// handrail
+			Material(0,128,0,255    , "ground_outdoor"),   // ground outdoor
+			Material(64,64,64,255   , "ground_indoor"),    // ground outdoor
+			Material(105,105,105,255, "stair"),	           // stair
+			Material(220,220,220,255, "handrail"),         // handrail
 
-		    Material(200,200,255,96),	// door (glass)
-		    Material(140,140,140,255),	// door (wood)
+			Material(200,200,255,96 , "door_glass"),       // door (glass)
+			Material(140,140,140,255, "door_wood"),        // door (wood)
 
-		    Material(135,135,135,255),	// concrete
-		    Material(240,240,255,96),	// glass
-		    Material(170,170,255,96),	// glass (metallized)
-		    Material(170,120,60,255),	// wood
-		    Material(200,200,200,255),	// drywall
+			Material(135,135,135,255, "concrete"),         // concrete
+			Material(240,240,255,96 , "glass"),            // glass
+			Material(170,170,255,96 , "glass_metallized"), // glass (metallized)
+			Material(170,120,60,255 , "wood"),	           // wood
+			Material(200,200,200,255, "drywall"),	       // drywall
+			Material(255,255,255,255, "metal"),			   // metal
 
-		    Material(255,255,255,255),	// object
 
-		    Material(235,235,235,255),	// default
+			Material(255,255,255,255, "object"),	       // object
+
+			Material(235,235,235,255, "dafult"),	       // default
 
 		};
 
-		int getMaterial(const Obstacle3D& o) const {
+		int getMaterialIdx(const Obstacle3D& o) const {
 
 			if (o.type == Floorplan3D::Obstacle3D::Type::ERROR)											{return 0;}
 
@@ -323,9 +328,16 @@ namespace Floorplan3D {
 
 			if (o.mat == Floorplan::Material::WOOD)													{return 10;}
 			if (o.mat == Floorplan::Material::DRYWALL)												{return 11;}
+			if (o.mat == Floorplan::Material::METAL)												{return 12;}
 
-			return 12;
 
+			return 13;
+
+		}
+
+		const Material& getMaterial(const Obstacle3D& o) const {
+			const int idx = getMaterialIdx(o);
+			return mats[idx];
 		}