Please ask this question, and questions like this, on <a href="http://answers.ros.org">answers.ros.org</a>.<br><br>I expect the problem is that in adding a single triangle you are adding a 2D shape, and the convex hull code isn&#39;t happy with a single 2D shape without volume.  I don&#39;t think collision checking will work against a 2D shape either.  I&#39;m not sure how many triangles you&#39;ll have to add to compute a convex hull and collision check successfully. A much better approach than trying to code this by hand is taking an .stl file for the mesh and using the function in geometric_shapes called createMeshFromFilename.  Then you can use the constuctObjectMsg function in planning_environment/util/construct_object.h to form the message.<br>
<br>-Gil<br><br><div class="gmail_quote">On Sat, Mar 10, 2012 at 6:25 PM, Arkapravo Bhaumik <span dir="ltr">&lt;<a href="mailto:arkapravobhaumik@gmail.com">arkapravobhaumik@gmail.com</a>&gt;</span> wrote:<br><blockquote class="gmail_quote" style="margin:0 0 0 .8ex;border-left:1px #ccc solid;padding-left:1ex">
Consider putting this question to <a href="http://answers.ros.org" target="_blank">answer.ros</a>, chances are that you may get better replies.<div class="HOEnZb"><div class="h5"><br><br><div class="gmail_quote">On 11 March 2012 03:11, Paul Heran Yang <span dir="ltr">&lt;<a href="mailto:heranyang@gmail.com" target="_blank">heranyang@gmail.com</a>&gt;</span> wrote:<br>


<blockquote class="gmail_quote" style="margin:0 0 0 .8ex;border-left:1px #ccc solid;padding-left:1ex"><div class="gmail_quote">Hi all,<div><br></div><div>I&#39;ve been trying to add meshes into collision object, but always get error: &quot;Unable to compute convex hull&quot;</div>


<div><br></div><div><div>    trimesh_object.type = arm_navigation_msgs::Shape::MESH;</div>

<div>    for (int i = 0; i &lt; 3; i++) {</div><div>        geometry_msgs::Point p;</div><div>        p.x = i;</div><div>        p.y = i+1;</div><div>        p.z = i+2;</div><div>        trimesh_object.vertices.push_back(p);</div>




</div><div>    }</div><div><br></div><div>    // then add {0, 1, 2} into trimesh_object.triangles</div>    collision_object.shapes.push_back(trimesh_object);<div><div><br></div><div>    geometry_msgs::Pose pose;</div></div>




<div><div>    collision_object.poses.push_back(pose);</div></div><div><br></div><div>    ...</div><div><div><br></div><div>    planning_scene_req.planning_scene_diff.collision_objects.push_back(collision_object);</div></div>




<div>    get_planning_scene_client.call(planning_scene_req, planning_scene_res) ...</div><div><br></div><div>I&#39;ve followed the instructions on <a href="http://www.ros.org/wiki/arm_navigation/Tutorials/Planning%20Scene/Adding%20Virtual%20Objects%20to%20the%20Planning%20Scene" target="_blank">http://www.ros.org/wiki/arm_navigation/Tutorials/Planning%20Scene/Adding%20Virtual%20Objects%20to%20the%20Planning%20Scene</a></div>




<div><br></div><div>All I&#39;m trying to do is just to add a simple triangle into the scene, but so far no luck. The above code just adds {0,1,2},{1,2,3},{2,3,4} into it. I also tried {0,0,1},{0,1,0},{1,0,0}. Nothing works.</div>




<div><br></div><div>I don&#39;t get why there&#39;s &quot;unable to compute convex hull&quot; error. Thanks in advance.</div><span><font color="#888888"><span><font color="#888888"><div><br></div><div>-Paul</div>

<div><br></div></font></span></font></span></div>


</blockquote></div>
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