Fixed OctoMap cmpil error when rtabmap is not built with OctoMap dep (https://github.com/introlab/rtabmap/issues/759#issuecomment-948766713). stereo_odometry: added check for identity stereo transform (same frame used for left and right).

src/MapsManager.cpp

@@ -69,7 +69,11 @@ MapsManager::MapsManager() :
 		assembledGround_(new pcl::PointCloud<pcl::PointXYZRGB>),
 		occupancyGrid_(new OccupancyGrid),
 		gridUpdated_(true),
+#ifdef WITH_OCTOMAP_MSGS
+#ifdef RTABMAP_OCTOMAP
 		octomap_(new OctoMap),
+#endif
+#endif
 		octomapTreeDepth_(16),
 		octomapUpdated_(true),
 		latching_(true)

src/nodelets/stereo_odometry.cpp

@@ -210,7 +210,20 @@ private:
 							cameraInfoLeft->header.stamp);
 					if(stereoTransform.isNull())
 					{
-						NODELET_ERROR("Parameter %s is false but we cannot get TF between the two cameras!", Parameters::kRtabmapImagesAlreadyRectified().c_str());
+						NODELET_ERROR("Parameter %s is false but we cannot get TF between the two cameras! (between frames %s and %s)",
+								Parameters::kRtabmapImagesAlreadyRectified().c_str(),
+								cameraInfoRight->header.frame_id.c_str(),
+								cameraInfoLeft->header.frame_id.c_str());
+						return;
+					}
+					else if(stereoTransform.isIdentity())
+					{
+						NODELET_ERROR("Parameter %s is false but we cannot get a valid TF between the two cameras! "
+								"Identity transform returned between left and right cameras. Verify that if TF between "
+								"the cameras is valid: \"rosrun tf tf_echo %s %s\".",
+								Parameters::kRtabmapImagesAlreadyRectified().c_str(),
+								cameraInfoRight->header.frame_id.c_str(),
+								cameraInfoLeft->header.frame_id.c_str());
 						return;
 					}
 				}