Added check for loaded STL file if it was saved in meters. Related to #4521 (Some files are imported in the wrong size)

src/libslic3r/Model.cpp

@@ -472,6 +472,29 @@ void Model::convert_from_imperial_units(bool only_small_volumes)
         }
 }
 
+bool Model::looks_like_saved_in_meters() const
+{
+    if (this->objects.size() == 0)
+        return false;
+
+    for (ModelObject* obj : this->objects)
+        if (obj->get_object_stl_stats().volume < 0.001) // 0.001 = 0.1*0.1*0.1;
+            return true;
+
+    return false;
+}
+
+void Model::convert_from_meters(bool only_small_volumes)
+{
+    double m_to_mm = 1000;
+    for (ModelObject* obj : this->objects)
+        if (! only_small_volumes || obj->get_object_stl_stats().volume < 0.001) { // 0.001 = 0.1*0.1*0.1;
+            obj->scale_mesh_after_creation(Vec3d(m_to_mm, m_to_mm, m_to_mm));
+            for (ModelVolume* v : obj->volumes)
+                v->source.is_converted_from_inches = true;
+        }
+}
+
 void Model::adjust_min_z()
 {
     if (objects.empty())

src/libslic3r/Model.hpp

@@ -1019,6 +1019,8 @@ public:
     void 		  convert_multipart_object(unsigned int max_extruders);
     bool          looks_like_imperial_units() const;
     void          convert_from_imperial_units(bool only_small_volumes);
+    bool          looks_like_saved_in_meters() const;
+    void          convert_from_meters(bool only_small_volumes);
 
     // Ensures that the min z of the model is not negative
     void 		  adjust_min_z();

src/slic3r/GUI/Plater.cpp

@@ -2415,13 +2415,24 @@ std::vector<size_t> Plater::priv::load_files(const std::vector<fs::path>& input_
             auto convert_from_imperial_units = [](Model& model, bool only_small_volumes) {
                 model.convert_from_imperial_units(only_small_volumes);
 //                wxGetApp().app_config->set("use_inches", "1");
-                wxGetApp().sidebar().update_ui_from_settings();
+//                wxGetApp().sidebar().update_ui_from_settings();
             };
 
             if (!is_project_file) {
                 if (imperial_units)
                     // Convert even if the object is big.
                     convert_from_imperial_units(model, false);
+                else if (model.looks_like_saved_in_meters()) {
+                    wxMessageDialog msg_dlg(q, format_wxstr(_L_PLURAL(
+                        "The object in file %s looks like saved in meters.\n"
+                        "Should I consider it as a saved in meters and convert it?",
+                        "Some objects in file %s look like saved in meters.\n"
+                        "Should I consider them as a saved in meters and convert them?", model.objects.size()), from_path(filename)) + "\n",
+                        _L("The object appears to be saved in meters"), wxICON_WARNING | wxYES | wxNO);
+                    if (msg_dlg.ShowModal() == wxID_YES)
+                        //FIXME up-scale only the small parts?
+                        model.convert_from_meters(true);
+                }
                 else if (model.looks_like_imperial_units()) {
                     wxMessageDialog msg_dlg(q, format_wxstr(_L_PLURAL(
                         "The object in file %s looks like saved in inches.\n"