Updating to use LabelEntry ids.

com.unity.perception/Runtime/GroundTruth/Labeling/LabelingConfiguration.cs

         /// <returns>Returns true if a match was found. False if not.</returns>
         public bool TryGetMatchingConfigurationEntry(Labeling labeling, out LabelEntry labelEntry)
         {
+            return TryGetMatchingConfigurationEntry(labeling, out labelEntry, out int _);
+        }
+
+        /// <summary>
+        /// Attempts to find the matching index in <see cref="LabelEntries"/> for the given <see cref="Labeling"/>.
+        /// </summary>
+        /// <remarks>
+        /// The matching index is the first class name in the given Labeling which matches an entry in <see cref="LabelEntries"/>.
+        /// </remarks>
+        /// <param name="labeling">The <see cref="Labeling"/> to match </param>
+        /// <param name="labelEntry">When this method returns, contains the matching <see cref="LabelEntry"/>, or <code>default</code> if no match was found.</param>
+        /// <param name="labelEntryIndex">When this method returns, contains the index of the matching <see cref="LabelEntry"/>, or <code>-1</code> if no match was found.</param>
+        /// <returns>Returns true if a match was found. False if not.</returns>
+        public bool TryGetMatchingConfigurationEntry(Labeling labeling, out LabelEntry labelEntry, out int labelEntryIndex)
+        {
             foreach (var labelingClass in labeling.labels)
             {
                 for (var i = 0; i < LabelEntries.Count; i++)
                     {
                         labelEntry = entry;
+                        labelEntryIndex = i;
+            labelEntryIndex = -1;
             labelEntry = default;
             return false;
         }

com.unity.perception/Runtime/GroundTruth/PerceptionCamera.cs

 
             if (produceSegmentationImages)
             {
-                var specs = LabelingConfiguration.LabelEntries.Select((l, index) => new SemanticSegmentationSpec()
+                var specs = LabelingConfiguration.LabelEntries.Select((l) => new SemanticSegmentationSpec()
-                    label_id = index,
+                    label_id = l.id,
                     label_name = l.label,
                     pixel_value = l.value
                 }).ToArray();
 
             if (produceObjectCountAnnotations || produceBoundingBoxAnnotations || produceRenderedObjectInfoMetric)
             {
-                var labelingMetricSpec = LabelingConfiguration.LabelEntries.Select((l, index) => new ObjectCountSpec()
+                var labelingMetricSpec = LabelingConfiguration.LabelEntries.Select((l) => new ObjectCountSpec()
-                    label_id = index,
+                    label_id = l.id,
                     label_name = l.label,
                 }).ToArray();
 
                 {
                     m_ClassCountValues[i] = new ClassCountValue()
                     {
-                        label_id = i,
+                        label_id = entries[i].id,
                         label_name = entries[i].label,
                         count = counts[i]
                     };

com.unity.perception/Runtime/GroundTruth/RenderedObjectInfoGenerator.cs

             }
         }
 
-        NativeList<int> m_InstanceIdToClassIdLookup;
+        NativeList<int> m_InstanceIdToLabelEntryIndexLookup;
         LabelingConfiguration m_LabelingConfiguration;
 
         // ReSharper disable once InvalidXmlDocComment
         public RenderedObjectInfoGenerator(LabelingConfiguration labelingConfiguration)
         {
             m_LabelingConfiguration = labelingConfiguration;
-            m_InstanceIdToClassIdLookup = new NativeList<int>(k_StartingObjectCount, Allocator.Persistent);
+            m_InstanceIdToLabelEntryIndexLookup = new NativeList<int>(k_StartingObjectCount, Allocator.Persistent);
         }
 
         /// <inheritdoc/>
             {
-                if (m_InstanceIdToClassIdLookup.Length <= instanceId)
+                if (m_InstanceIdToLabelEntryIndexLookup.Length <= instanceId)
-                    m_InstanceIdToClassIdLookup.Resize((int)instanceId + 1, NativeArrayOptions.ClearMemory);
+                    m_InstanceIdToLabelEntryIndexLookup.Resize((int)instanceId + 1, NativeArrayOptions.ClearMemory);
-                m_InstanceIdToClassIdLookup[(int)instanceId] = entry.id;
+                m_InstanceIdToLabelEntryIndexLookup[(int)instanceId] = entry.id;
             }
         }
 
                 for (var i = 0; i < keyValueArrays.Keys.Length; i++)
                 {
                     var instanceId = keyValueArrays.Keys[i];
-                    if (m_InstanceIdToClassIdLookup.Length <= instanceId)
+                    if (m_InstanceIdToLabelEntryIndexLookup.Length <= instanceId)
-                    var classId = m_InstanceIdToClassIdLookup[instanceId];
+                    var classId = m_InstanceIdToLabelEntryIndexLookup[instanceId];
                     classCounts[classId]++;
                     var renderedObjectInfo = keyValueArrays.Values[i];
                     var boundingBox = renderedObjectInfo.boundingBox;
         public bool TryGetLabelIdFromInstanceId(int instanceId, out int labelId)
         {
             labelId = -1;
-            if (m_InstanceIdToClassIdLookup.Length <= instanceId)
+            if (m_InstanceIdToLabelEntryIndexLookup.Length <= instanceId)
-            labelId = m_InstanceIdToClassIdLookup[instanceId];
+            labelId = m_InstanceIdToLabelEntryIndexLookup[instanceId];
             return true;
         }
 
-            m_InstanceIdToClassIdLookup.Dispose();
+            m_InstanceIdToLabelEntryIndexLookup.Dispose();
         }
     }
 }