#0  0x00007ffff38ae91b in DescendingPlaneSort (A=0xc329228, B=0x110)
    at /home/jhoare/gazebo-hg/deps/opende/src/heightfield.cpp:912
#1  0x00007ffff38ae998 in dxHeightfield::sortPlanes (this=0x4b8acb0,
    numPlanes=0)
    at /home/jhoare/gazebo-hg/deps/opende/src/heightfield.cpp:924
#2  0x00007ffff38afbbf in dxHeightfield::dCollideHeightfieldZone (
    this=0x4b8acb0, minX=127, maxX=129, minZ=128, maxZ=130, o2=0x185eef0,
    numMaxContactsPossible=1, flags=1, contact=0x7fffffffc5f0, skip=96)
    at /home/jhoare/gazebo-hg/deps/opende/src/heightfield.cpp:1449
#3  0x00007ffff38b0771 in dCollideHeightfield (o1=0x4b8acb0, o2=0x185eef0,
    flags=1, contact=0x7fffffffc5f0, skip=96)
    at /home/jhoare/gazebo-hg/deps/opende/src/heightfield.cpp:1792
#4  0x00007ffff387ebee in dCollide (o1=0x185eef0, o2=0x4b8acb0, flags=1,
    contact=0x7fffffffc5f0, skip=96)
    at /home/jhoare/gazebo-hg/deps/opende/src/collision_kernel.cpp:320
#5  0x00007ffff33b4fe7 in gazebo::physics::ODEMultiRayShape::UpdateCallback (
    _data=0x1607e20, _o1=0x185eef0, _o2=0x4b8acb0)
    at /home/jhoare/gazebo-hg/gazebo/physics/ode/ODEMultiRayShape.cc:157
#6  0x00007ffff38866f9 in collideAABBs (g1=0x185eef0, g2=0x4b8acb0,
    data=0x1607e20,
    callback=0x7ffff33b4c7a <gazebo::physics::ODEMultiRayShape::UpdateCallback(void*, dxGeom*, dxGeom*)>)
    at /home/jhoare/gazebo-hg/deps/opende/src/collision_space_internal.h:81
#7  0x00007ffff38870a6 in dxSimpleSpace::collide2 (this=0x1600500,
    _data=0x1607e20, geom=0x4b8acb0,
    callback=0x7ffff33b4c7a <gazebo::physics::ODEMultiRayShape::UpdateCallback(void*, dxGeom*, dxGeom*)>)
    at /home/jhoare/gazebo-hg/deps/opende/src/collision_space.cpp:288
#8  0x00007ffff3888385 in dSpaceCollide2 (g1=0x1600500, g2=0x195eef0,
    data=0x1607e20,
    callback=0x7ffff33b4c7a <gazebo::physics::ODEMultiRayShape::UpdateCallback(void*, dxGeom*, dxGeom*)>)
    at /home/jhoare/gazebo-hg/deps/opende/src/collision_space.cpp:819
#9  0x00007ffff33b4d75 in gazebo::physics::ODEMultiRayShape::UpdateCallback (
    _data=0x1607e20, _o1=0x1600500, _o2=0x195eef0)
    at /home/jhoare/gazebo-hg/gazebo/physics/ode/ODEMultiRayShape.cc:101
#10 0x00007ffff38881cf in swap_callback (data=0x7fffffffc990, g1=0x195eef0,
    g2=0x1600500)
    at /home/jhoare/gazebo-hg/deps/opende/src/collision_space.cpp:774
#11 0x00007ffff38866f9 in collideAABBs (g1=0x195eef0, g2=0x1600500,
    data=0x7fffffffc990,
    callback=0x7ffff3888193 <swap_callback(void*, dxGeom*, dxGeom*)>)
    at /home/jhoare/gazebo-hg/deps/opende/src/collision_space_internal.h:81
#12 0x00007ffff3887e50 in dxHashSpace::collide2 (this=0x14423c0,
    _data=0x7fffffffc990, geom=0x1600500,
    callback=0x7ffff3888193 <swap_callback(void*, dxGeom*, dxGeom*)>)
    at /home/jhoare/gazebo-hg/deps/opende/src/collision_space.cpp:610
#13 0x00007ffff3888333 in dSpaceCollide2 (g1=0x1603f90, g2=0x14423c0,
    data=0x1607e20,
    callback=0x7ffff33b4c7a <gazebo::physics::ODEMultiRayShape::UpdateCallback(void*, dxGeom*, dxGeom*)>)
    at /home/jhoare/gazebo-hg/deps/opende/src/collision_space.cpp:814
#14 0x00007ffff33b4bdd in gazebo::physics::ODEMultiRayShape::UpdateRays (
    this=0x1607e20)
    at /home/jhoare/gazebo-hg/gazebo/physics/ode/ODEMultiRayShape.cc:81
#15 0x00007ffff70dd871 in gazebo::physics::MultiRayShape::Update (
    this=0x1607e20)
    at /home/jhoare/gazebo-hg/gazebo/physics/MultiRayShape.cc:165
#16 0x00007ffff6ce4c2f in gazebo::sensors::RaySensor::UpdateImpl (
    this=0x15fd4f0)
    at /home/jhoare/gazebo-hg/gazebo/sensors/RaySensor.cc:232
#17 0x00007ffff6cbcb4a in gazebo::sensors::Sensor::Update (this=0x15fd4f0,
    _force=false)
    at /home/jhoare/gazebo-hg/gazebo/sensors/Sensor.cc:134
#18 0x00007ffff6cccd7d in gazebo::sensors::SensorManager::Update (
    this=0x7ffff73903e0, _force=false)
    at /home/jhoare/gazebo-hg/gazebo/sensors/SensorManager.cc:100
#19 0x00007ffff6cb8b3d in gazebo::sensors::run_once (_force=false)
    at /home/jhoare/gazebo-hg/gazebo/sensors/Sensors.cc:88
#20 0x000000000046655f in gazebo::Server::Run (this=0x6de0e0)
    at /home/jhoare/gazebo-hg/gazebo/Server.cc:356
#21 0x000000000046217f in main (argc=4, argv=0x7fffffffd018)
    at /home/jhoare/gazebo-hg/gazebo/server_main.cc:32