diff --git a/Triangulation_on_sphere_2/demo/Triangulation_on_sphere_2/Viewer.cpp b/Triangulation_on_sphere_2/demo/Triangulation_on_sphere_2/Viewer.cpp
index 03e188afc4d..3bcaa4f3eac 100644
--- a/Triangulation_on_sphere_2/demo/Triangulation_on_sphere_2/Viewer.cpp
+++ b/Triangulation_on_sphere_2/demo/Triangulation_on_sphere_2/Viewer.cpp
@@ -14,10 +14,10 @@ Viewer::Viewer(QWidget* parent )
 {
   draw_balls = true;
   draw_inputs = false;
-  create_flat_sphere(1.0f, pos_sphere, normals, 9);
   trivial_center.push_back(0.);
   trivial_center.push_back(0.);
   trivial_center.push_back(0.);
+  radius_ = 1.0;
 }
 
 void Viewer::compile_shaders()
@@ -222,6 +222,9 @@ void Viewer::compute_elements()
 {
   pos_sphere_inter.clear();
   normals_inter.clear();
+  pos_sphere.clear();
+  normals.clear();
+  create_flat_sphere(static_cast<float>(radius_), pos_sphere, normals, 9);
   create_flat_sphere(0.05f, pos_sphere_inter, normals_inter, 36);
 
   pos_points.resize(0);
@@ -256,6 +259,8 @@ void Viewer::compute_elements()
       pos_lines.push_back(arc[i+1].z());
     }
   }
+  setSceneRadius(radius_*1.3);
+  showEntireScene();
 }
 
 void Viewer::attrib_buffers(CGAL::QGLViewer* viewer)
diff --git a/Triangulation_on_sphere_2/demo/Triangulation_on_sphere_2/Viewer.h b/Triangulation_on_sphere_2/demo/Triangulation_on_sphere_2/Viewer.h
index 3677a988cff..ab38432f9e8 100644
--- a/Triangulation_on_sphere_2/demo/Triangulation_on_sphere_2/Viewer.h
+++ b/Triangulation_on_sphere_2/demo/Triangulation_on_sphere_2/Viewer.h
@@ -89,7 +89,8 @@ public:
     normals_inter.clear();
     normals_lines.clear();
 
-    min_edge_size = 0.01 * tos.geom_traits().radius();
+    radius_ = tos.geom_traits().radius();
+    min_edge_size = 0.01 * radius_;
 
     std::copy(begin, end, std::back_inserter(inputs));
     build_the_boundary(tos);
@@ -162,6 +163,7 @@ private:
   typedef void (APIENTRYP PFNGLVERTEXATTRIBDIVISORARBPROC) (GLuint index, GLuint divisor);
   PFNGLDRAWARRAYSINSTANCEDARBPROC glDrawArraysInstanced;
   PFNGLVERTEXATTRIBDIVISORARBPROC glVertexAttribDivisor;
+  double radius_;
 
   void initialize_buffers();
   void compute_elements();
diff --git a/Triangulation_on_sphere_2/demo/Triangulation_on_sphere_2/main.cpp b/Triangulation_on_sphere_2/demo/Triangulation_on_sphere_2/main.cpp
index 915a79233ac..7e81a3f8bf8 100644
--- a/Triangulation_on_sphere_2/demo/Triangulation_on_sphere_2/main.cpp
+++ b/Triangulation_on_sphere_2/demo/Triangulation_on_sphere_2/main.cpp
@@ -10,6 +10,7 @@
 #include <QApplication>
 #include <QMainWindow>
 #include <QFileDialog>
+#include <QInputDialog>
 
 #include <boost/iterator/transform_iterator.hpp>
 
@@ -62,7 +63,7 @@ public slots:
     read_points(filename.toUtf8().data(), std::back_inserter(lst_pt));
 
     const Point_3 center(0,0,0);
-    const FT radius = 1.0;
+    const FT radius = QInputDialog::getDouble(nullptr, "Radius", "Radius of the sphere", 1.0, 0.0);
     Projection_traits traits(center, radius);
     Projected_DToS2 dtos(lst_pt.begin(), lst_pt.end(), traits);