increase transmission render target default size to 1024x1024

loaders/src/glTF/2.0/Extensions/KHR_materials_transmission.ts

@@ -37,7 +37,7 @@ class TransmissionHelper {
      */
     private static _getDefaultOptions(): ITransmissionHelperOptions {
         return {
-            renderSize: 512
+            renderSize: 1024
         };
     }