fix comment and tests

Cesium3DTilesSelection/src/Tile.cpp

@@ -632,10 +632,10 @@ void Tile::update(
             std::move(this->_pContent->pNewTileContext));
       }
 
-      // If this tile has no model, set its geometric error very high so we
-      // refine past it. Note that "no" model is different from having a model,
-      // but it is blank. In the latter case, we'll happily render nothing in
-      // the space of this tile, which is sometimes useful.
+      // If this tile has no model, we want to unconditionally refine past it.
+      // Note that "no" model is different from having a model, but it is blank.
+      // In the latter case, we'll happily render nothing in the space of this
+      // tile, which is sometimes useful.
       if (!this->_pContent->model) {
         this->setUnconditionallyRefine(true);
       }

Cesium3DTilesSelection/test/TestTilesetSelectionAlgorithm.cpp

@@ -628,9 +628,8 @@ TEST_CASE("Test additive refinement") {
             "tileset3/tileset3.json") {
           REQUIRE(doesTileMeetSSE(viewState, child, tileset));
         } else {
-          // external tileset has always geometric error over 999999, so it
-          // won't meet sse
-          REQUIRE(!doesTileMeetSSE(viewState, child, tileset));
+          // external tilesets get unconditionally refined
+          REQUIRE(root->getUnconditionallyRefine());
 
           // expect the children to meet sse and begin loading the content
           REQUIRE(child.getChildren().size() == 1);