Please ask this question, and questions like this, on answers.ros.org. I expect the problem is that in adding a single triangle you are adding a 2D shape, and the convex hull code isn't happy with a single 2D shape without volume. I don't think collision checking will work against a 2D shape either. I'm not sure how many triangles you'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. -Gil On Sat, Mar 10, 2012 at 6:25 PM, Arkapravo Bhaumik < arkapravobhaumik@gmail.com> wrote: > Consider putting this question to answer.ros , > chances are that you may get better replies. > > > On 11 March 2012 03:11, Paul Heran Yang wrote: > >> Hi all, >> >> I've been trying to add meshes into collision object, but always get >> error: "Unable to compute convex hull" >> >> trimesh_object.type = arm_navigation_msgs::Shape::MESH; >> for (int i = 0; i < 3; i++) { >> geometry_msgs::Point p; >> p.x = i; >> p.y = i+1; >> p.z = i+2; >> trimesh_object.vertices.push_back(p); >> } >> >> // then add {0, 1, 2} into trimesh_object.triangles >> collision_object.shapes.push_back(trimesh_object); >> >> geometry_msgs::Pose pose; >> collision_object.poses.push_back(pose); >> >> ... >> >> >> planning_scene_req.planning_scene_diff.collision_objects.push_back(collision_object); >> get_planning_scene_client.call(planning_scene_req, >> planning_scene_res) ... >> >> I've followed the instructions on >> http://www.ros.org/wiki/arm_navigation/Tutorials/Planning%20Scene/Adding%20Virtual%20Objects%20to%20the%20Planning%20Scene >> >> All I'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. >> >> I don't get why there's "unable to compute convex hull" error. Thanks in >> advance. >> >> -Paul >> >> > _______________________________________________ > ros-users mailing list > ros-users@code.ros.org > https://code.ros.org/mailman/listinfo/ros-users > >