Various update

ScriptableRenderPipeline/HDRenderPipeline/HDRP/Editor/Lighting/HDLightEditor.cs

             public SerializedProperty directionalIntensity;
             public SerializedProperty punctualIntensity;
             public SerializedProperty areaIntensity;
-            public SerializedProperty displayBounceIntensity;
             public SerializedProperty spotInnerPercent;
             public SerializedProperty lightDimmer;
             public SerializedProperty fadeDistance;
                 directionalIntensity = o.Find(x => x.directionalIntensity),
                 punctualIntensity = o.Find(x => x.punctualIntensity),
                 areaIntensity = o.Find(x => x.areaIntensity),
-                displayBounceIntensity = o.Find(x => x.displayBounceIntensity),
                 spotInnerPercent = o.Find(x => x.m_InnerSpotPercent),
                 lightDimmer = o.Find(x => x.lightDimmer),
                 fadeDistance = o.Find(x => x.fadeDistance),
                 }
             }
 
-            EditorGUI.BeginChangeCheck();
-            {
-                EditorGUILayout.PropertyField(m_AdditionalLightData.displayBounceIntensity, s_Styles.lightBounceIntensity);
-
-                // No indirect shadow support for anything but directional
-                if (m_LightShape != LightShape.Directional &&
-                    settings.shadowsType.enumValueIndex != (int)LightShadows.None &&
-                    settings.isRealtime && m_AdditionalLightData.displayBounceIntensity.floatValue > 0.0f &&
-                    !settings.lightType.hasMultipleDifferentValues)
-                {
-                    EditorGUILayout.HelpBox(s_Styles.indirectBounceShadowWarning.text, MessageType.Info);
-                }
-            }
-
-            if (EditorGUI.EndChangeCheck())
-            {
-                // Lightmapper don't divide correctly by PI when calculating bounce of analytic light (Lambert is rho / PI but lightmapper only do rho),
-                // so we need to handle the divide ourselves through this workaround (only for analytical light)
-                settings.bounceIntensity.floatValue = m_AdditionalLightData.displayBounceIntensity.floatValue / Mathf.PI;
-            }
-
             settings.DrawLightmapping();
 
             EditorGUI.BeginChangeCheck(); // For GI we need to detect any change on additional data and call SetLightDirty
                 EditorGUILayout.Slider(m_AdditionalShadowData.normalBiasMin, 0.0f, 5.0f, s_Styles.normalBiasMin);
                 if (EditorGUI.EndChangeCheck())
                 {
-                    // Link min to max and don't expose normalBiasScale (useless when min == max)                    
+                    // Link min to max and don't expose normalBiasScale (useless when min == max)
                     m_AdditionalShadowData.normalBiasMax = m_AdditionalShadowData.normalBiasMin;
                 }
                 //EditorGUILayout.PropertyField(m_AdditionalShadowData.normalBiasMax, s_Styles.normalBiasMax);

ScriptableRenderPipeline/HDRenderPipeline/HDRP/Lighting/Light/HDAdditionalLightData.cs

         // To be able to have correct default values for our lights and to also control the conversion of intensity from the light editor (so it is compatible with GI)
         // we add intensity (for each type of light we want to manage).
         public float directionalIntensity   = 10000.0f; // Sun Light default to 10000 lux
-        public float punctualIntensity      = 600.0f;   // Light default to 600 lumens, i.e ~48 candela
-        public float areaIntensity          = 600.0f;   // Light default to 600 lumens
-        public float displayBounceIntensity = 1.0f;   // override bound intensity of built-in unity to take into account the PI shift observe in GI (as GI don't divide by PI)
+        public float punctualIntensity      = 600.0f;   // Light default to 600 lumen, i.e ~48 candela
+        public float areaIntensity          = 600.0f;   // Light default to 600 lumen
 
         [Range(0.0f, 100.0f)]
         public float m_InnerSpotPercent = 0.0f; // To display this field in the UI this need to be public

ScriptableRenderPipeline/HDRenderPipeline/HDRP/Lighting/LightUtils.cs

         // Area light are convert to luminance (cd/(m^2*steradian)) with the following formulation: Luminous Power / (Area * PI * steradian)
 
         // Ref: Moving Frostbite to PBR
+
+        // convert intensity (lumen) to candela
         public static float ConvertPointLightIntensity(float intensity)
         {
             return intensity / (4.0f * Mathf.PI);
+        // convert intensity (lumen) to candela
         public static float ConvertSpotLightIntensity(float intensity, float angle, bool exact)
         {
             return exact ? intensity / (2.0f * (1.0f - Mathf.Cos(angle / 2.0f)) * Mathf.PI) : intensity / Mathf.PI;
+        // convert intensity (lumen) to candela
+        // convert intensity (lumen) to nits
+        // convert intensity (lumen) to nits
+        // convert intensity (lumen) to nits
+        // convert intensity (lumen) to nits
         public static float calculateLineLightArea(float intensity, float lineRadius, float lineWidth)
         {
             return intensity / (2.0f * Mathf.PI * lineRadius * lineWidth * Mathf.PI);