diff --git a/models/csharp/UrchinModels.cs b/models/csharp/UrchinModels.cs
index eaadd86..3c91256 100644
--- a/models/csharp/UrchinModels.cs
+++ b/models/csharp/UrchinModels.cs
@@ -185,16 +185,16 @@ public MeshModel(string id, string shape, Vector3 position, Color color, Vector3
 public struct ParticleSystemModel
 {
     public string ID;
-    public string Shape;
+    public int N;
     public string Material;
     public Vector3[] Positions;
     public float[] Sizes;
     public Color[] Colors;
 
-    public ParticleSystemModel(string id, string shape, string material, Vector3[] positions, float[] sizes, Color[] colors)
+    public ParticleSystemModel(string id, int n, string material, Vector3[] positions, float[] sizes, Color[] colors)
     {
         ID = id;
-        Shape = shape;
+        N = n;
         Material = material;
         Positions = positions;
         Sizes = sizes;
diff --git a/models/schemas/urchin/ParticleSystemModel.json b/models/schemas/urchin/ParticleSystemModel.json
index 013809f..7e7512b 100644
--- a/models/schemas/urchin/ParticleSystemModel.json
+++ b/models/schemas/urchin/ParticleSystemModel.json
@@ -1 +1 @@
-{"$defs": {"Color": {"properties": {"r": {"default": 1, "maximum": 1.0, "minimum": 0.0, "title": "R", "type": "number"}, "g": {"default": 1, "maximum": 1.0, "minimum": 0.0, "title": "G", "type": "number"}, "b": {"default": 1, "maximum": 1.0, "minimum": 0.0, "title": "B", "type": "number"}, "a": {"default": 1, "maximum": 1.0, "minimum": 0.0, "title": "A", "type": "number"}}, "title": "Color", "type": "object"}, "Vector3": {"properties": {"x": {"default": 0.0, "title": "X", "type": "number"}, "y": {"default": 0.0, "title": "Y", "type": "number"}, "z": {"default": 0.0, "title": "Z", "type": "number"}}, "title": "Vector3", "type": "object"}}, "properties": {"ID": {"title": "Id", "type": "string"}, "Shape": {"title": "Shape", "type": "string"}, "Material": {"title": "Material", "type": "string"}, "Positions": {"items": {"$ref": "#/$defs/Vector3"}, "title": "Positions", "type": "array"}, "Sizes": {"items": {"type": "number"}, "title": "Sizes", "type": "array"}, "Colors": {"items": {"$ref": "#/$defs/Color"}, "title": "Colors", "type": "array"}}, "required": ["ID", "Shape", "Material", "Positions", "Sizes", "Colors"], "title": "ParticleSystemModel", "type": "object"}
\ No newline at end of file
+{"$defs": {"Color": {"properties": {"r": {"default": 1, "maximum": 1.0, "minimum": 0.0, "title": "R", "type": "number"}, "g": {"default": 1, "maximum": 1.0, "minimum": 0.0, "title": "G", "type": "number"}, "b": {"default": 1, "maximum": 1.0, "minimum": 0.0, "title": "B", "type": "number"}, "a": {"default": 1, "maximum": 1.0, "minimum": 0.0, "title": "A", "type": "number"}}, "title": "Color", "type": "object"}, "Vector3": {"properties": {"x": {"default": 0.0, "title": "X", "type": "number"}, "y": {"default": 0.0, "title": "Y", "type": "number"}, "z": {"default": 0.0, "title": "Z", "type": "number"}}, "title": "Vector3", "type": "object"}}, "properties": {"ID": {"title": "Id", "type": "string"}, "N": {"title": "N", "type": "integer"}, "Material": {"default": "circle", "title": "Material", "type": "string"}, "Positions": {"default": [], "items": {"$ref": "#/$defs/Vector3"}, "title": "Positions", "type": "array"}, "Sizes": {"default": [], "items": {"type": "number"}, "title": "Sizes", "type": "array"}, "Colors": {"default": [], "items": {"$ref": "#/$defs/Color"}, "title": "Colors", "type": "array"}}, "required": ["ID", "N"], "title": "ParticleSystemModel", "type": "object"}
\ No newline at end of file