diff --git a/offline_ray_tracer/source/main.cpp b/offline_ray_tracer/source/main.cpp
index 3527c796fcd5aafcbd8335aa1ecc349a2256aa19..432b1d53f01d70eabdc5c9f1561e3bbc10b42fdc 100644
--- a/offline_ray_tracer/source/main.cpp
+++ b/offline_ray_tracer/source/main.cpp
@@ -85,8 +85,10 @@ std::int32_t main(std::int32_t argc, char** argv)
     {
       std::cout << "Loading slice " << slice << ".\n";
       last_slice = slice;
-      pd_mapper->SetInputData(rt::poly_data_io        ::read(settings.data_filepaths[slice].geometry));
-      ug_mapper->SetInputData(rt::unstructured_grid_io::read(settings.data_filepaths[slice].volume  ));
+      if (!settings.data_filepaths[slice].geometry.empty())
+        pd_mapper->SetInputData(rt::poly_data_io        ::read(settings.data_filepaths[slice].geometry));
+      if (!settings.data_filepaths[slice].volume  .empty())
+        ug_mapper->SetInputData(rt::unstructured_grid_io::read(settings.data_filepaths[slice].volume  ));
     }
 
     std::cout << "Rendering frame " << current_time << ".\n";