Hi Matei, I get it now ;) If I want to model my own objects (for any reason), how precise and complete must the triangle meshes be for the object detection to work? Regards. Rene 2010/7/13 Matei Ciocarlie : > Hi Rene, > > The models are stored in the database as triangle meshes. For display, > we found it more clear to render them as wireframe rather than > triangle meshes, as the wireframe still allows the original point > cloud to show trough a little bit. > > The detection is done by comparing the perceived point cloud against > the triangle mesh stored in the database. > > Best, > Matei > > On Tue, Jul 13, 2010 at 9:03 AM, René Ladan wrote: >> Hi Matei, >> >> so the wireframe is only used for display reasons and to store the models >> more efficiently in the database. Is the detection then realized by comparing >> perceived pointcloud with the pointcloud version of the database models? >> >> Regards, >> Rene >> >> 2010/7/13 Matei Ciocarlie : >>> Hi Rene, >>> >>> That's generally correct, except for the transformation of the point >>> cloud into wireframe. The tabletop_object_detector uses sensor data >>> directly as point clouds. You might see a wireframe displayed on the >>> screen but that's only after a database model has been recognized. The >>> wireframe is that of the model, superimposed on the point cloud that >>> has been recognized. >>> >>> Matei >>> >>> On Tue, Jul 13, 2010 at 4:59 AM, René Ladan wrote: >>>> Hi, >>>> >>>> below is a text I intend to include in a report. Do I get the basic ideas right? >>>> >>>> Regards, >>>> Rene >>>> >>>> Object handling consists of several steps, which are performed by the >>>> tabletop_object_detector (and other) nodes. >>>> •       Get an image of the object (e.g. a pool ball) from e.g. a stereo >>>> camera with texturing or e.g. a laser range finder. >>>> •       Transform the image (either a stereo-photo or a “sphere” of >>>> distances) into a point cloud. A point cloud is a collection of >>>> points, where all points have a number of pre-defined attributes, like >>>> spatial coordinates, color, or neighborhood density. Point clouds are >>>> the universal data structures for performing 3-dimensional algorithms >>>> within ROS. TODO: figure out the algorithm >>>> •       Transform the point cloud into a wireframe. TODO: figure out which >>>> algorithm is used for this. >>>> •       Now that an approximate wireframe model of the object is available, >>>> (because the camera images are probably imperfect), this model can be >>>> compared to a database of existing, perfect wireframe models. Because >>>> the models are stored as blobs in the database, the approximation is >>>> done in the ROS node. The database is thus only used a storage >>>> backend. >>>> •       The comparison algorithm, given the actual model at one side and the >>>> database models at the other side, is able to calculate the likelihood >>>> that the presented object matches a or multiple objects in the >>>> database (e.g. for a ping-pong ball, it could say “90% pool ball, 8% >>>> bottle cap, and 2% unknown”). >>>> >>>> -- >>>> http://www.rene-ladan.nl/ >>>> >>>> GPG fingerprint = E738 5471 D185 7013 0EE0  4FC8 3C1D 6F83 12E1 84F6 >>>> (subkeys.pgp.net) >>>> _______________________________________________ >>>> ros-users mailing list >>>> ros-users@code.ros.org >>>> https://code.ros.org/mailman/listinfo/ros-users >>>> >>> >>> >>> >>> -- >>> Matei Ciocarlie >>> Research Scientist >>> Willow Garage Inc. >>> 650-475-9780 >>> _______________________________________________ >>> ros-users mailing list >>> ros-users@code.ros.org >>> https://code.ros.org/mailman/listinfo/ros-users >>> >> _______________________________________________ >> ros-users mailing list >> ros-users@code.ros.org >> https://code.ros.org/mailman/listinfo/ros-users >> > > > > -- > Matei Ciocarlie > Research Scientist > Willow Garage Inc. > 650-475-9780 > _______________________________________________ > ros-users mailing list > ros-users@code.ros.org > https://code.ros.org/mailman/listinfo/ros-users >