diff --git a/matlab/+gtsam/plotProjectedCylinderSamples.m b/matlab/+gtsam/plotProjectedCylinderSamples.m
new file mode 100644
index 000000000..5d9a06713
--- /dev/null
+++ b/matlab/+gtsam/plotProjectedCylinderSamples.m
@@ -0,0 +1,36 @@
+function plotProjectedCylinderSamples(visiblePoints3, cameraPose, figID)
+% plot the visible projected points on the cylinders
+% author: Zhaoyang Lv
+
+    import gtsam.*
+
+    figure(figID);
+
+    holdstate = ishold;
+    hold on
+
+    %plotCamera(cameraPose, 5);
+    
+    pointsNum = size(visiblePoints3, 1)
+    
+    for i=1:pointsNum
+        ray = visiblePoints3{i}.between(cameraPose.translation()).vector();
+        dist = norm(ray);
+        
+        p = plot3(visiblePoints3{i}.x, visiblePoints3{i}.y, visiblePoints3{i}.z, ...
+            'o', 'MarkerFaceColor', 'Green');
+        
+        for t=0:0.1:dist
+            marchingRay = ray * t;
+            p.XData = visiblePoints3{i}.x + marchingRay(1);
+            p.YData = visiblePoints3{i}.y + marchingRay(2);
+            p.ZData = visiblePoints3{i}.z + marchingRay(3);
+            drawnow update
+        end
+        
+    end
+    
+    if ~holdstate
+        hold off
+    end
+end
\ No newline at end of file
diff --git a/matlab/+gtsam/points2DTrackMonocular.m b/matlab/+gtsam/points2DTrackMonocular.m
new file mode 100644
index 000000000..1c1e641bf
--- /dev/null
+++ b/matlab/+gtsam/points2DTrackMonocular.m
@@ -0,0 +1,40 @@
+function pts2dTracksmon = points2DTrackMonocular(K, cameraPoses, imageSize, cylinders)
+% Assess how accurately we can reconstruct points from a particular monocular camera setup. 
+% After creation of the factor graph for each track, linearize it around ground truth. 
+% There is no optimization
+% @author: Zhaoyang Lv
+
+import gtsam.*
+
+%% create graph
+graph = NonlinearFactorGraph;
+
+%% add a constraint on the starting pose
+poseNoiseSigmas = [0.001 0.001 0.001 0.1 0.1 0.1]';
+posePriorNoise  = noiseModel.Diagonal.Sigmas(poseNoiseSigmas);
+firstPose = cameraPoses{1};
+graph.add(PriorFactorPose3(symbol('x', l), firstPose, posePriorNoise));
+
+cameraPosesNum = size(cameraPoses, 1);
+
+%% add measurements
+initialEstimate = Values;
+for i = 1:cameraPosesNum
+    [visiblePoints3, visiblePointsCylinderIdx] = cylinderSampleProjection(K, cameraPoses{i}, imageSize, cylinders);
+    
+    pointsNum = size(visiblePoints, 1);
+    
+    %% not finished
+    %for j = 1:pointsNum
+    %    graph.add();
+    %end   
+end
+
+marginals = Marginals(graph, initialEstimate);
+
+% should use all the points num to replace the num 100
+for i = 1:100 
+   marginals.marginalCovariance(symbol('p',i));
+end
+
+end