<?xml version="1.0"?><gz:world xmlns:gz="http://playerstage.sourceforge.net/gazebo/xmlschema/#gz" xmlns:model="http://playerstage.sourceforge.net/gazebo/xmlschema/#model" xmlns:sensor="http://playerstage.sourceforge.net/gazebo/xmlschema/#sensor" xmlns:window="http://playerstage.sourceforge.net/gazebo/xmlschema/#window" xmlns:param="http://playerstage.sourceforge.net/gazebo/xmlschema/#params" xmlns:ui="http://playerstage.sourceforge.net/gazebo/xmlschema/#params">  <param:Global>    <gravity>0.0 0.0 -9.8</gravity>    <utmOffset>0 0</utmOffset>  </param:Global>  <model:ObserverCam>    <id>userCam0</id>    <xyz>0 0 60</xyz>    <rpy>0 30 40</rpy>    <imageSize>640 480</imageSize>    <displayRays>false</displayRays>    <farClip>1000</farClip>    <shadeSmooth>true</shadeSmooth>    <polygonFill>true</polygonFill>  </model:ObserverCam>  <model:LightSource>    <id>0</id>    <xyz>65 65 400</xyz>    <attenuation>0.1 0.005 0.0</attenuation>  </model:LightSource>  <model:Terrain>    <!-- Use gzbuilder to create the terrain file-->    <!-- ex: gzbuilder -i terrain.png -o terrain.gzb -n -v 20 -e 2 -s 10 -t 10 -->    <terrainFile>terrain.gzb</terrainFile>    <xyz>0 0 0</xyz>    <color>0 1.0 0.0</color>    <textureFile>grid.ppm</textureFile>  </model:Terrain></gz:world>