When external guess is provided, don't report lost for the first ever frame (only on reset). Updated Odom/ResetCountdown description. (#1588)

guilib/src/ui/preferencesDialog.ui

@@ -63,7 +63,7 @@
           <property name="geometry">
            <rect>
             <x>0</x>
-            <y>-3050</y>
+            <y>0</y>
             <width>713</width>
             <height>4779</height>
            </rect>
@@ -95,7 +95,7 @@
                 <enum>QFrame::Raised</enum>
                </property>
                <property name="currentIndex">
-                <number>5</number>
+                <number>19</number>
                </property>
                <widget class="QWidget" name="page_22">
                 <layout class="QVBoxLayout" name="verticalLayout_29" stretch="0,0">
@@ -15733,7 +15733,7 @@ If set to false, classic RTAB-Map loop closure detection is done using only imag
                       <item row="3" column="1">
                        <widget class="QLabel" name="label_47">
                         <property name="text">
-                         <string>Automatically reset odometry after X consecutive images on which odometry cannot be computed (value=0 disables auto-reset). When reset, the odometry starts from the last pose computed.</string>
+                         <string>Automatically reset odometry after X consecutive images where odometry cannot be computed (a value of 0 disables auto-reset). When a reset occurs, odometry resumes from the last successfully computed pose with large covariance to trigger a new map. If external odometry is used, it will also be reset based on the motion estimated relative to the last computed pose but no large covariance will be received, so that a new map won't be triggered.</string>
                         </property>
                         <property name="wordWrap">
                          <bool>true</bool>