Mirroring mesh in SDF: visual works but collision component errors

[HomeworldL]

Environment

• OS Version: Ubuntu 22.04
• ROS2 Version: Binary ROS2 Humble
• Gazebo Version: Ignition Gazebo Fortress

Description

Expected behavior:
I want to mirror the mesh in Gezebo. I use <scale>1 1 -1</scale> to mirror along the Z-axis. In theory, similar to MuJoCo, the mesh should be mirrored for both the visual and collision components.

Actual behavior:
Mirroring the visual component works, but the outer and inner surfaces are swapped. Mirroring the collision component results in an error.

Steps to Reproduce

1. Create an SDF file with the following content and name it test_mirror.sdf:

   <?xml version="1.0" ?>
   
   <sdf version='1.9'>
   <world name='empty'>
       <physics name='1ms' type='ignored'>
       <max_step_size>0.001</max_step_size>
       <real_time_factor>1</real_time_factor>
       <real_time_update_rate>1000</real_time_update_rate>
       </physics>
       <plugin name='gz::sim::systems::Physics' filename='ignition-gazebo-physics-system'/>
       <plugin name='gz::sim::systems::UserCommands' filename='ignition-gazebo-user-commands-system'/>
       <plugin name='gz::sim::systems::SceneBroadcaster' filename='ignition-gazebo-scene-broadcaster-system'/>
       <plugin name='gz::sim::systems::Contact' filename='ignition-gazebo-contact-system'/>
       <plugin name="ignition::gazebo::systems::ForceTorque" filename="ignition-gazebo-forcetorque-system" />
       <gravity>0 0 0</gravity>
       <magnetic_field>6e-06 2.3e-05 -4.2e-05</magnetic_field>
       <atmosphere type='adiabatic'/>
       <scene>
       <ambient>0.4 0.4 0.4 1</ambient>
       <background>0.7 0.7 0.7 1</background>
       <shadows>true</shadows>
       </scene>
       <light name='sun' type='directional'>
       <pose>0 0 10 0 -0 0</pose>
       <cast_shadows>true</cast_shadows>
       <intensity>1</intensity>
       <direction>-0.5 0.1 -0.9</direction>
       <diffuse>0.8 0.8 0.8 1</diffuse>
       <specular>0.2 0.2 0.2 1</specular>
       <attenuation>
           <range>1000</range>
           <linear>0.01</linear>
           <constant>0.90000000000000002</constant>
           <quadratic>0.001</quadratic>
       </attenuation>
       <spot>
           <inner_angle>0</inner_angle>
           <outer_angle>0</outer_angle>
           <falloff>0</falloff>
       </spot>
       </light>
       <model name='simple_box'>
       <static>false</static>
       <pose>0 0 0.5 0 0 0</pose>
       <link name='link'>
           <visual name='visual'>
           <geometry>
               <mesh>
               <uri>cube_test.dae</uri>
               </mesh>
           </geometry>
           </visual>
           <collision name='collision'>
           <geometry>
               <mesh>
               <uri>cube_test.dae</uri>
               </mesh>
           </geometry>
           </collision>
       </link>
       </model>
       <model name='simple_box_mirror'>
       <static>false</static>
       <pose>3 0 0.5 0 0 0</pose>
       <link name='link'>
           <visual name='visual'>
           <geometry>
               <mesh>
               <uri>cube_test.dae</uri>
               <scale>1 1 -1</scale>
               </mesh>
           </geometry>
           </visual>
           <collision name='collision'>
           <geometry>
               <mesh>
               <uri>cube_test.dae</uri>
               <scale>1 1 -1</scale>
               </mesh>
           </geometry>
           </collision>
       </link>
       </model>
   </world>
   </sdf>

cube_test.zip

1. Run the following command:

   ign gazebo -v 1 test_mirror.sdf

Output

libEGL warning: egl: failed to create dri2 screen
libEGL warning: egl: failed to create dri2 screen
ign gazebo server: ./dart/dynamics/MeshShape.cpp:240: void dart::dynamics::MeshShape::setScale(const Vector3d&): Assertion `(scale.array() > 0.0).all()' failed.
Stack trace (most recent call last):
#31   Object "/lib/x86_64-linux-gnu/libruby-3.0.so.3.0", at 0x7f598dc7ba4e, in 
#30   Object "/lib/x86_64-linux-gnu/libruby-3.0.so.3.0", at 0x7f598dba69ac, in rb_protect
#29   Object "/lib/x86_64-linux-gnu/libruby-3.0.so.3.0", at 0x7f598dd3ec61, in rb_yield
#28   Object "/lib/x86_64-linux-gnu/libruby-3.0.so.3.0", at 0x7f598dd3a30c, in rb_vm_exec
#27   Object "/lib/x86_64-linux-gnu/libruby-3.0.so.3.0", at 0x7f598dd34c96, in 
#26   Object "/lib/x86_64-linux-gnu/libruby-3.0.so.3.0", at 0x7f598dd31fc5, in 
#25   Object "/lib/x86_64-linux-gnu/libruby-3.0.so.3.0", at 0x7f598dd2fc34, in 
#24   Object "/usr/lib/x86_64-linux-gnu/ruby/3.0.0/fiddle.so", at 0x7f598936e44b, in 
#23   Object "/lib/x86_64-linux-gnu/libruby-3.0.so.3.0", at 0x7f598dcfd088, in rb_nogvl
#22   Object "/usr/lib/x86_64-linux-gnu/ruby/3.0.0/fiddle.so", at 0x7f598936dd6b, in 
#21   Object "/lib/x86_64-linux-gnu/libffi.so.8", at 0x7f598935f492, in 
#20   Object "/lib/x86_64-linux-gnu/libffi.so.8", at 0x7f5989362e2d, in 
#19   Object "/usr/lib/x86_64-linux-gnu/libignition-gazebo6-ign.so.6.16.0", at 0x7f5988860e20, in runServer
#18   Object "/lib/x86_64-linux-gnu/libignition-gazebo6.so.6", at 0x7f5988441ad9, in 
#17   Object "/lib/x86_64-linux-gnu/libignition-gazebo6.so.6", at 0x7f5988452d3a, in ignition::gazebo::v6::SimulationRunner::Run(unsigned long)
#16   Object "/lib/x86_64-linux-gnu/libignition-gazebo6.so.6", at 0x7f59884525cd, in ignition::gazebo::v6::SimulationRunner::Step(ignition::gazebo::v6::UpdateInfo const&)
#15   Object "/lib/x86_64-linux-gnu/libignition-gazebo6.so.6", at 0x7f5988449581, in ignition::gazebo::v6::SimulationRunner::UpdateSystems()
#14   Object "/usr/lib/x86_64-linux-gnu/ign-gazebo-6/plugins/libignition-gazebo-physics-system.so", at 0x7f59804133b2, in ignition::gazebo::v6::systems::Physics::Update(ignition::gazebo::v6::UpdateInfo const&, ignition::gazebo::v6::EntityComponentManager&)
#13   Object "/usr/lib/x86_64-linux-gnu/ign-gazebo-6/plugins/libignition-gazebo-physics-system.so", at 0x7f5980404905, in ignition::gazebo::v6::systems::PhysicsPrivate::CreatePhysicsEntities(ignition::gazebo::v6::EntityComponentManager const&)
#12   Object "/usr/lib/x86_64-linux-gnu/ign-gazebo-6/plugins/libignition-gazebo-physics-system.so", at 0x7f598040372c, in ignition::gazebo::v6::systems::PhysicsPrivate::CreateCollisionEntities(ignition::gazebo::v6::EntityComponentManager const&)
#11   Object "/usr/lib/x86_64-linux-gnu/ign-gazebo-6/plugins/libignition-gazebo-physics-system.so", at 0x7f5980482ca9, in void ignition::gazebo::v6::EntityComponentManager::EachNew<ignition::gazebo::v6::components::Component<std::add_lvalue_reference<void>, ignition::gazebo::v6::components::CollisionTag, ignition::gazebo::v6::serializers::DefaultSerializer<std::add_lvalue_reference<void> > >, ignition::gazebo::v6::components::Component<std::__cxx11::basic_string<char, std::char_traits<char>, std::allocator<char> >, ignition::gazebo::v6::components::NameTag, ignition::gazebo::v6::serializers::StringSerializer>, ignition::gazebo::v6::components::Component<ignition::math::v6::Pose3<double>, ignition::gazebo::v6::components::PoseTag, ignition::gazebo::v6::serializers::DefaultSerializer<ignition::math::v6::Pose3<double> > >, ignition::gazebo::v6::components::Component<sdf::v12::Geometry, ignition::gazebo::v6::components::GeometryTag, ignition::gazebo::v6::serializers::ComponentToMsgSerializer<sdf::v12::Geometry, ignition::msgs::Geometry> >, ignition::gazebo::v6::components::Component<sdf::v12::Collision, ignition::gazebo::v6::components::CollisionElementTag, ignition::gazebo::v6::serializers::ComponentToMsgSerializer<sdf::v12::Collision, ignition::msgs::Collision> >, ignition::gazebo::v6::components::Component<unsigned long, ignition::gazebo::v6::components::ParentEntityTag, ignition::gazebo::v6::serializers::DefaultSerializer<unsigned long> > >(ignition::gazebo::v6::EntityComponentManager::identity<std::function<bool (unsigned long const&, ignition::gazebo::v6::components::Component<std::add_lvalue_reference<void>, ignition::gazebo::v6::components::CollisionTag, ignition::gazebo::v6::serializers::DefaultSerializer<std::add_lvalue_reference<void> > > const*, ignition::gazebo::v6::components::Component<std::__cxx11::basic_string<char, std::char_traits<char>, std::allocator<char> >, ignition::gazebo::v6::components::NameTag, ignition::gazebo::v6::serializers::StringSerializer> const*, ignition::gazebo::v6::components::Component<ignition::math::v6::Pose3<double>, ignition::gazebo::v6::components::PoseTag, ignition::gazebo::v6::serializers::DefaultSerializer<ignition::math::v6::Pose3<double> > > const*, ignition::gazebo::v6::components::Component<sdf::v12::Geometry, ignition::gazebo::v6::components::GeometryTag, ignition::gazebo::v6::serializers::ComponentToMsgSerializer<sdf::v12::Geometry, ignition::msgs::Geometry> > const*, ignition::gazebo::v6::components::Component<sdf::v12::Collision, ignition::gazebo::v6::components::CollisionElementTag, ignition::gazebo::v6::serializers::ComponentToMsgSerializer<sdf::v12::Collision, ignition::msgs::Collision> > const*, ignition::gazebo::v6::components::Component<unsigned long, ignition::gazebo::v6::components::ParentEntityTag, ignition::gazebo::v6::serializers::DefaultSerializer<unsigned long> > const*)> >::type) const
#10   Object "/usr/lib/x86_64-linux-gnu/ign-gazebo-6/plugins/libignition-gazebo-physics-system.so", at 0x7f598040d4b8, in 
#9    Object "/usr/lib/x86_64-linux-gnu/ign-gazebo-6/plugins/libignition-gazebo-physics-system.so", at 0x7f5980432478, in ignition::physics::mesh::AttachMeshShapeFeature::Link<ignition::physics::FeaturePolicy<double, 3ul>, ignition::gazebo::v6::systems::PhysicsPrivate::MeshFeatureList>::AttachMeshShape(std::__cxx11::basic_string<char, std::char_traits<char>, std::allocator<char> > const&, ignition::common::Mesh const&, Eigen::Transform<double, 3, 1, 0> const&, Eigen::Matrix<double, 3, 1, 0, 3, 1> const&)
#8    Object "/usr/lib/x86_64-linux-gnu/ign-physics-5/engine-plugins/libignition-physics-dartsim-plugin.so", at 0x7f594df2bde7, in ignition::physics::dartsim::ShapeFeatures::AttachMeshShape(ignition::physics::Identity const&, std::__cxx11::basic_string<char, std::char_traits<char>, std::allocator<char> > const&, ignition::common::Mesh const&, Eigen::Transform<double, 3, 1, 0> const&, Eigen::Matrix<double, 3, 1, 0, 3, 1> const&)
#7    Object "/usr/lib/x86_64-linux-gnu/ign-physics-5/engine-plugins/libignition-physics-dartsim-plugin.so", at 0x7f594def14f7, in ignition::physics::dartsim::CustomMeshShape::CustomMeshShape(ignition::common::Mesh const&, Eigen::Matrix<double, 3, 1, 0, 3, 1> const&)
#6    Object "/lib/x86_64-linux-gnu/libdart.so.6.12", at 0x7f594daa524a, in dart::dynamics::MeshShape::MeshShape(Eigen::Matrix<double, 3, 1, 0, 3, 1> const&, aiScene const*, dart::common::Uri const&, std::shared_ptr<dart::common::ResourceRetriever>)
#5    Object "/lib/x86_64-linux-gnu/libdart.so.6.12", at 0x7f594da9c0a2, in dart::dynamics::MeshShape::setScale(Eigen::Matrix<double, 3, 1, 0, 3, 1> const&)
#4    Object "/lib/x86_64-linux-gnu/libc.so.6", at 0x7f598d910e95, in __assert_fail
#3    Object "/lib/x86_64-linux-gnu/libc.so.6", at 0x7f598d8ff71a, in 
#2    Object "/lib/x86_64-linux-gnu/libc.so.6", at 0x7f598d8ff7f2, in abort
#1    Object "/lib/x86_64-linux-gnu/libc.so.6", at 0x7f598d919475, in raise
#0    Object "/lib/x86_64-linux-gnu/libc.so.6", at 0x7f598d96d9fc, in pthread_kill
Aborted (Signal sent by tkill() 1569981 1000)

Found that outer and inner surfaces are swapped.

Note

I noticed that the error message mentioned Dart, so I tested <physics name='1ms' type='ode'> and , but nothing changed.

[iche033]

the mesh class just applies simple scaling to vertices. To handle negative scale, I think we'll need to invert the normals, e.g. by updating the indices

[HomeworldL]

Will there be any improvements in future versions？

[azeey]

@HomeworldL This would be great to have, but we don't have anyone that's able to work on it. Would you be interested in contributing a PR?