diff --git a/Assets/UniGLTF/Runtime/UniGLTF/IO/TextureIO/OcclusionMetallicRoughnessConverter.cs b/Assets/UniGLTF/Runtime/UniGLTF/IO/TextureIO/OcclusionMetallicRoughnessConverter.cs
index 72ad2d1af..514ed6067 100644
--- a/Assets/UniGLTF/Runtime/UniGLTF/IO/TextureIO/OcclusionMetallicRoughnessConverter.cs
+++ b/Assets/UniGLTF/Runtime/UniGLTF/IO/TextureIO/OcclusionMetallicRoughnessConverter.cs
@@ -69,7 +69,11 @@ namespace UniGLTF
             }
             else if (occlusionTexture != null)
             {
-                throw new NotImplementedException("occlusion only");
+                var copyTexture = TextureConverter.CopyTexture(occlusionTexture, glTFTextureTypes.OcclusionMetallicRoughness, null);
+                copyTexture.SetPixels32(copyTexture.GetPixels32().Select(x => ImportPixel(default, metallicFactor, roughnessFactor, x)).ToArray());
+                copyTexture.Apply();
+                copyTexture.name = occlusionTexture.name;
+                return copyTexture;
             }
             else
             {
diff --git a/Assets/UniGLTF/Runtime/UniGLTF/IO/TextureIO/TextureFactory.cs b/Assets/UniGLTF/Runtime/UniGLTF/IO/TextureIO/TextureFactory.cs
index 70872c48c..24f999f5b 100644
--- a/Assets/UniGLTF/Runtime/UniGLTF/IO/TextureIO/TextureFactory.cs
+++ b/Assets/UniGLTF/Runtime/UniGLTF/IO/TextureIO/TextureFactory.cs
@@ -178,7 +178,11 @@ namespace UniGLTF
 
                 case GetTextureParam.TextureTypes.StandardMap:
                     {
-                        var baseTexture = await GetOrCreateBaseTexture(awaitCaller, gltf, param.Index0.Value, false);
+                        TextureLoadInfo baseTexture = default;
+                        if (param.Index0.HasValue)
+                        {
+                            baseTexture = await GetOrCreateBaseTexture(awaitCaller, gltf, param.Index0.Value, false);
+                        }
                         TextureLoadInfo occlusionBaseTexture = default;
                         if (param.Index1.HasValue)
                         {