diff --git a/apps/Viewer/Scene.cpp b/apps/Viewer/Scene.cpp
index 69683dc75..83bb21ad7 100644
--- a/apps/Viewer/Scene.cpp
+++ b/apps/Viewer/Scene.cpp
@@ -706,7 +706,7 @@ void Scene::TogleSceneBox()
 }
 
 
-void Scene::CastRay(const Ray3& ray, int action)
+void Scene::CastRay(const Ray3& ray, int action, int mods)
 {
 	if (!IsOctreeValid())
 		return;
@@ -747,6 +747,19 @@ void Scene::CastRay(const Ray3& ray, int action)
 				face[1], window.selectionPoints[1].x, window.selectionPoints[1].y, window.selectionPoints[1].z,
 				face[2], window.selectionPoints[2].x, window.selectionPoints[2].y, window.selectionPoints[2].z
 			);
+			if ((mods&(GLFW_MOD_CONTROL|GLFW_MOD_SHIFT)) && scene.mesh.HasTexture()) {
+				String dbgOut;
+				cv::Mat dbgImg;
+				scene.mesh.ListIncidenteFaces();
+				scene.mesh.ListIncidenteFaceFaces();
+				const bool bSaveToFile = (mods&GLFW_MOD_ALT);
+				dbgOut = scene.mesh.PlotTexturePatch((MVS::Mesh::FIndex)intRay.pick.idx, face_patch_ids, dbgImg, bSaveToFile);
+				if (!dbgOut.IsEmpty()) {
+					DEBUG_EXTRA("Saved texture patch as %s", dbgOut.c_str());
+				} else {
+					cv::imshow(dbgOut, dbgImg);	
+				}
+			}
 		} else {
 			window.selectionType = Window::SEL_NA;
 		}
diff --git a/apps/Viewer/Scene.h b/apps/Viewer/Scene.h
index d1e360833..1e093e93d 100644
--- a/apps/Viewer/Scene.h
+++ b/apps/Viewer/Scene.h
@@ -60,6 +60,7 @@ class Scene
 	Window window;
 	ImageArr images; // scene photos
 	ImageArr textures; // mesh textures
+	MVS::Mesh::FaceIdxArr face_patch_ids;
 
 	OctreePoints octPoints;
 	OctreeMesh octMesh;
@@ -97,7 +98,7 @@ class Scene
 
 	void Center();
 	void TogleSceneBox();
-	void CastRay(const Ray3&, int);
+	void CastRay(const Ray3&, int, int);
 protected:
 	static void* ThreadWorker(void*);
 };
diff --git a/apps/Viewer/Window.cpp b/apps/Viewer/Window.cpp
index 63bbe1a19..390b7b2c6 100644
--- a/apps/Viewer/Window.cpp
+++ b/apps/Viewer/Window.cpp
@@ -366,7 +366,7 @@ void Window::Key(GLFWwindow* window, int k, int scancode, int action, int mod)
 	g_mapWindows[window]->Key(k, scancode, action, mod);
 }
 
-void Window::MouseButton(int button, int action, int /*mods*/)
+void Window::MouseButton(int button, int action, int mods)
 {
 	switch (button) {
 	case GLFW_MOUSE_BUTTON_LEFT: {
@@ -394,7 +394,7 @@ void Window::MouseButton(int button, int action, int /*mods*/)
 			const Eigen::Vector3d start(invV.topRightCorner<3,1>());
 			const Eigen::Vector4d ray_wor(invV*ray_eye);
 			const Eigen::Vector3d dir(ray_wor.topRows<3>().normalized());
-			clbkRayScene(Ray3d(start, dir), action);
+			clbkRayScene(Ray3d(start, dir), action, mods);
 		}
 	} break;
 	case GLFW_MOUSE_BUTTON_MIDDLE: {
diff --git a/apps/Viewer/Window.h b/apps/Viewer/Window.h
index 34195ae31..18adf6690 100644
--- a/apps/Viewer/Window.h
+++ b/apps/Viewer/Window.h
@@ -100,7 +100,7 @@ class Window
 	ClbkExportScene clbkExportScene;
 	typedef DELEGATE<void (void)> ClbkCenterScene;
 	ClbkCenterScene clbkCenterScene;
-	typedef DELEGATE<void (const Ray3&, int)> ClbkRayScene;
+	typedef DELEGATE<void (const Ray3&, int, int)> ClbkRayScene;
 	ClbkRayScene clbkRayScene;
 	typedef DELEGATE<void (void)> ClbkCompilePointCloud;
 	ClbkCompilePointCloud clbkCompilePointCloud;
diff --git a/libs/IO/OBJ.cpp b/libs/IO/OBJ.cpp
index 0c1f5309b..df4789f70 100644
--- a/libs/IO/OBJ.cpp
+++ b/libs/IO/OBJ.cpp
@@ -191,6 +191,7 @@ bool ObjModel::Save(const String& fileName, unsigned precision, bool texLossless
 bool ObjModel::Load(const String& fileName)
 {
 	ASSERT(vertices.empty() && groups.empty() && material_lib.materials.empty());
+	const String path(Util::getFilePath(fileName));
 	std::ifstream fin(fileName.c_str());
 	String line, keyword;
 	std::istringstream in;
@@ -254,7 +255,7 @@ bool ObjModel::Load(const String& fileName)
 		} else
 		if (keyword == "mtllib") {
 			in >> keyword;
-			if (!material_lib.Load(keyword))
+			if (!material_lib.Load(MAKE_PATH_FULL(path, keyword)))
 				return false;
 		} else
 		if (keyword == "usemtl") {
diff --git a/libs/MVS/Mesh.cpp b/libs/MVS/Mesh.cpp
index 76678846b..429fac49d 100644
--- a/libs/MVS/Mesh.cpp
+++ b/libs/MVS/Mesh.cpp
@@ -398,6 +398,54 @@ void Mesh::ComputeNormalVertices()
 }
 #endif
 
+uint32_t Mesh::ComputeTexturePatchFaces(FaceIdxArr& face_patch_ids) const {
+	ASSERT(faceTexcoords.size() == faces.size() * 3);
+	face_patch_ids.Resize(faces.GetSize());
+	face_patch_ids.MemsetValue(NO_ID);
+	std::stack<FIndex> stack_faces;
+	uint32_t patch_id = 0;
+	FOREACH(idx_face, faces) {
+		if (face_patch_ids[idx_face] != NO_ID)
+			continue;
+		face_patch_ids[idx_face] = patch_id;
+		stack_faces.push(idx_face);
+		do {
+			FIndex iF = stack_faces.top();
+			stack_faces.pop();
+			const Mesh::FaceFaces& ffaces = faceFaces[iF];
+			for (int i = 0; i < 3; ++i) {
+				const FIndex iFAdj = ffaces[i];
+				if (iFAdj == NO_ID || face_patch_ids[iFAdj] != NO_ID)
+					continue;
+				VIndex iV0, iV1; //indexes of a common vertex
+				for (int v0 = 0; v0 < 3; ++v0) {
+					const Face& f = faces[iF];
+					const Face& fAdj = faces[iFAdj];
+					bool bCommon = false;
+					for (int v1 = 0; v1 < 3; ++v1) {
+						if (f[v0] == fAdj[v1]) {
+							iV0 = v0;
+							iV1 = v1;
+							bCommon = true;
+							break;
+						}
+					}
+					if (bCommon)
+						break;
+				}
+				const TexCoord tcV = faceTexcoords[iF * 3 + iV0];
+				const TexCoord tcAdj = faceTexcoords[iFAdj * 3 + iV1];
+				if (tcV.x == tcAdj.x && tcV.y == tcAdj.y) {
+					face_patch_ids[iFAdj] = patch_id;
+					stack_faces.push(iFAdj);
+				}
+			}
+		} while (!stack_faces.empty());
+		++patch_id;
+	}
+	return patch_id;
+} // ComputeTexturePatchFaces
+
 // Smoothen the normals for each face
 //  - fMaxGradient: maximum angle (in degrees) difference between neighbor normals that is
 //    allowed to take into consideration; higher angles are ignored
@@ -4086,6 +4134,46 @@ REAL Mesh::ComputeVolume() const
 		volume += ComputeTriangleVolume(vertices[face[0]], vertices[face[1]], vertices[face[2]]);
 	return volume;
 }
+
+String Mesh::PlotTexturePatch(const FIndex dbgFaceId, FaceIdxArr& face_patch_ids, cv::Mat& imgOut, const bool bSaveToFile) const {
+	// split texture in patches
+	if (face_patch_ids.size() != faces.size()) {
+		ComputeTexturePatchFaces(face_patch_ids);
+	}
+	// get the list of all faces from the same patch as debug face
+	cList<Mesh::FIndex> patchFaces;
+	const uint32_t dbgPatchId(face_patch_ids[dbgFaceId]);
+	FOREACH(idx_face, face_patch_ids) {
+		if (dbgPatchId == face_patch_ids[idx_face])
+			patchFaces.emplace_back(idx_face);
+	}
+	const Mesh::Face fDbg = faces[dbgFaceId];
+	cv::Mat imgDbg;
+	textureDiffuse.copyTo(imgDbg);
+	AABB2f boundingBox(true);
+	FOREACH(fIdx, patchFaces) {
+		const Mesh::FIndex& fId = patchFaces[fIdx];
+		const Mesh::TexCoord& texDbgCoordsV0 = faceTexcoords[fId * 3]; boundingBox.Insert(texDbgCoordsV0);
+		const Mesh::TexCoord& texDbgCoordsV1 = faceTexcoords[fId * 3 + 1]; boundingBox.Insert(texDbgCoordsV1);
+		const Mesh::TexCoord& texDbgCoordsV2 = faceTexcoords[fId * 3 + 2]; boundingBox.Insert(texDbgCoordsV2);
+		cv::line(imgDbg, texDbgCoordsV0, texDbgCoordsV1, cv::Scalar(50, 50, 250));
+		cv::line(imgDbg, texDbgCoordsV0, texDbgCoordsV2, cv::Scalar(50, 50, 250));
+		cv::line(imgDbg, texDbgCoordsV2, texDbgCoordsV1, cv::Scalar(50, 50, 250));
+		if (fId == dbgFaceId) {
+			cv::circle(imgDbg, texDbgCoordsV0, 3, cv::Scalar(100, 150, 250), 2);
+			cv::circle(imgDbg, texDbgCoordsV1, 3, cv::Scalar(100, 150, 250), 2);
+			cv::circle(imgDbg, texDbgCoordsV2, 3, cv::Scalar(100, 150, 250), 2);
+		}
+	}
+	cv::Rect sourceRect(FLOOR(boundingBox.ptMin.x()), FLOOR(boundingBox.ptMin.y()), CEIL(boundingBox.ptMax.x() - boundingBox.ptMin.x()), CEIL(boundingBox.ptMax.y() - boundingBox.ptMin.y())); // ROI of the patch
+	imgDbg(sourceRect).copyTo(imgOut);
+	if (bSaveToFile) {
+		String sImgName = String::FormatString("dbgPatch_%d_%d.jpg", dbgPatchId, dbgFaceId);
+		cv::imwrite(MAKE_PATH_SAFE(sImgName), imgOut);
+		return sImgName;
+	}
+	return String();
+}
 /*----------------------------------------------------------------*/
 
 
diff --git a/libs/MVS/Mesh.h b/libs/MVS/Mesh.h
index f91028407..2cf058386 100644
--- a/libs/MVS/Mesh.h
+++ b/libs/MVS/Mesh.h
@@ -161,6 +161,7 @@ class MVS_API Mesh
 	void ListBoundaryVertices();
 	void ComputeNormalFaces();
 	void ComputeNormalVertices();
+	uint32_t ComputeTexturePatchFaces(FaceIdxArr& face_patch_ids) const;
 
 	void SmoothNormalFaces(float fMaxGradient=25.f, float fOriginalWeight=0.5f, unsigned nIterations=3);
 
@@ -209,6 +210,8 @@ class MVS_API Mesh
 	REAL ComputeArea() const;
 	REAL ComputeVolume() const;
 
+	String PlotTexturePatch(const FIndex dbgFaceId, FaceIdxArr& face_patch_ids=FaceIdxArr(), cv::Mat& imgOut=cv::Mat(), const bool bSaveToFile=true) const;
+
 	void SamplePoints(unsigned numberOfPoints, PointCloud&) const;
 	void SamplePoints(REAL samplingDensity, PointCloud&) const;
 	void SamplePoints(REAL samplingDensity, unsigned mumPointsTheoretic, PointCloud&) const;