diff --git a/Build/.qglviewer.xml b/Build/.qglviewer.xml
deleted file mode 100644
index 3228740..0000000
--- a/Build/.qglviewer.xml
+++ /dev/null
@@ -1,30 +0,0 @@
-<!DOCTYPE QGLVIEWER>
-<QGLViewer version="2.6.3">
-  <State stereo="false">
-    <foregroundColor blue="25" red="217" green="22"/>
-    <backgroundColor blue="255" red="217" green="228"/>
-  </State>
-  <Display FPSIsDisplayed="false" gridIsDrawn="false" axisIsDrawn="false" cameraIsEdited="false"/>
-  <Geometry width="800" fullScreen="false" posX="100" posY="127" height="600"/>
-  <Camera>
-    <Parameters zClippingCoefficient="1.73205" Type="PERSPECTIVE" fieldOfView="0.785398" sceneRadius="22.4054" zNearCoefficient="0.005" orthoCoef="0.670991">
-      <SceneCenter y="1" x="1" z="1"/>
-    </Parameters>
-    <Stereo physScreenWidth="0.5" focusDistance="54.0913" IODist="0.062"/>
-    <ManipulatedCameraFrame>
-      <position y="-36.9988" x="45.4908" z="-1.12818"/>
-      <orientation q2="0.174868" q1="0.411944" q0="0.590319" q3="0.671749"/>
-      <ManipulatedParameters zoomSens="1" rotSens="1" transSens="1" spinSens="0.3" wheelSens="1"/>
-      <ManipulatedCameraParameters rotatesAroundUpVector="false" flySpeed="0.224054" zoomsOnPivotPoint="false">
-        <sceneUpVector y="1" x="0" z="0"/>
-      </ManipulatedCameraParameters>
-    </ManipulatedCameraFrame>
-  </Camera>
-  <ManipulatedFrame>
-    <position y="0" x="0" z="0"/>
-    <orientation q2="0" q1="0" q0="0" q3="1"/>
-    <ManipulatedParameters zoomSens="1" rotSens="1" transSens="1" spinSens="0.3" wheelSens="1"/>
-  </ManipulatedFrame>
-  <Light pos_light_y="-84.9391" pos_light_x="10.6884" pos_light_z="127.287"/>
-  <Rendering mode="0"/>
-</QGLViewer>
diff --git a/external/DGtal/CMakeLists.txt b/external/DGtal/CMakeLists.txt
index a0e846b..fe5832a 100644
--- a/external/DGtal/CMakeLists.txt
+++ b/external/DGtal/CMakeLists.txt
@@ -2,14 +2,15 @@ cmake_minimum_required(VERSION 3.15)
 
 include(FetchContent)
 
-set(WITH_QGLVIEWER true)
-set(WITH_QT5 true)
-set(BUILD_EXAMPLES OFF)
+set(WITH_QGLVIEWER true CACHE INTERNAL "")
+set(WITH_QT5 true CACHE INTERNAL "")
+set(BUILD_EXAMPLES OFF CACHE INTERNAL "")
 
 FetchContent_Declare(
   DGtal
   URL https://github.com/DGtal-team/DGtal/archive/refs/tags/1.2.tar.gz
-  URL_HASH MD5=19e443ca4f3927c9b9eff742cdfa138f
-  DEPENDS libQGLViewer_ep-build)
+  URL_HASH MD5=19e443ca4f3927c9b9eff742cdfa138f)
 
 FetchContent_MakeAvailable(DGtal)
+
+target_link_libraries(DGtal PRIVATE libQGLViewer)
diff --git a/external/libQGLViewer/CMakeLists.txt b/external/libQGLViewer/CMakeLists.txt
index 88fe2d7..9528e00 100644
--- a/external/libQGLViewer/CMakeLists.txt
+++ b/external/libQGLViewer/CMakeLists.txt
@@ -3,39 +3,49 @@ cmake_minimum_required(VERSION 3.15)
 include(FetchContent)
 
 FetchContent_Declare(
-  libQGLViewer
+  libQGLViewer_sources
   URL http://www.libqglviewer.com/src/libQGLViewer-2.7.2.tar.gz
-  URL_HASH MD5=a9d965d1ce41f7db6b34f440bb74f061
-  CONFIGURE_COMMAND "qmake ${CMAKE_CURRENT_SOURCE_DIR}/QGLViewer/QGLViewer.pro"
-  STEP_TARGETS build
-  # BUILD_BYPRODUCTS ${CMAKE_CURRENT_SOURCE_DIR}/QGLViewer/libQGLViewer-qt5.so
-  LOG_DOWNLOAD true
-  LOG_CONFIGURE true
-  LOG_BUILD true
-  LOG_INSTALL true)
+  URL_HASH MD5=a9d965d1ce41f7db6b34f440bb74f061)
 
-ExternalProject_Get_property(libQGLViewer_ep SOURCE_DIR)
-message("libqglviewer_ep src dir: ${SOURCE_DIR}")
-ExternalProject_Get_property(libQGLViewer_ep CONFIGURE_COMMAND)
-message("libqglviewer_ep configure command: ${CONFIGURE_COMMAND}")
-# ExternalProject_Get_property(libQGLViewer_ep BUILD_BYPRODUCTS)
-# message("libqglviewer_ep build byproducts: ${BUILD_BYPRODUCTS}")
+FetchContent_MakeAvailable(libQGLViewer_sources)
+FetchContent_GetProperties(
+  libQGLViewer_sources
+  SOURCE_DIR libQGLViewer_SOURCE_DIR
+  BINARY_DIR libQGLViewer_BINARY_DIR)
 
-set(QGLVIEWER_INCLUDE_DIR
-  $<BUILD_INTERFACE:${SOURCE_DIR}>
-  $<INSTALL_INTERFACE:include>
-  CACHE PATH "")
-# # Can't use find_library as the library isn't there at config time
-# find_library(QGLVIEWER_LIBRARIES
-#   NAMES qglviewer-qt4 qglviewer QGLViewer QGLViewer2 QGLViewer-qt5
-#   PATHS ${SOURCE_DIR}
-#   PATH_SUFFIXES QGLViewer QGLViewer/release)
-set(QGLVIEWER_LIBRARIES
-  $<BUILD_INTERFACE:${SOURCE_DIR}/QGLViewer/libQGLViewer-qt5.so>
-  $<INSTALL_INTERFACE:lib/libQGLViewer-qt5.so>
-  CACHE FILEPATH "")
+find_program(QMAKE qmake)
+execute_process(
+  WORKING_DIRECTORY ${libQGLViewer_BINARY_DIR}
+  COMMAND "${QMAKE}" "${libQGLViewer_SOURCE_DIR}/QGLViewer/QGLViewer.pro"
+  COMMAND_ECHO STDERR
+  OUTPUT_VARIABLE QGLVIEWER_CFG_OUT
+  ERROR_VARIABLE QGLVIEWER_CFG_OUT
+  ECHO_OUTPUT_VARIABLE
+  ECHO_ERROR_VARIABLE
+  RESULT_VARIABLE QGLVIEWER_CFG_RES)
+message("QGLViewer configuration result: ${QGLVIEWER_CFG_RES}")
+
+find_program(MAKE make)
+include(ProcessorCount)
+ProcessorCount(NCORES)
+execute_process(
+  WORKING_DIRECTORY ${libQGLViewer_BINARY_DIR}
+  COMMAND "${MAKE}" "-j${NCORES}"
+  COMMAND_ECHO STDERR
+  OUTPUT_VARIABLE QGLVIEWER_BUILD_OUT
+  ERROR_VARIABLE QGLVIEWER_BUILD_OUT
+  ECHO_OUTPUT_VARIABLE
+  ECHO_ERROR_VARIABLE
+  RESULT_VARIABLE QGLVIEWER_BUILD_RES)
+message("QGLViewer build result: ${QGLVIEWER_BUILD_RES}")
 
 add_library(libQGLViewer INTERFACE)
+
+target_include_directories(libQGLViewer INTERFACE ${libQGLViewer_SOURCE_DIR})
+
+# QGLViewer moves its build output back to its source dir
+find_library(QGLVIEWER_LIBRARIES
+  NAMES qglviewer-qt4 qglviewer QGLViewer QGLViewer2 QGLViewer-qt5
+  PATHS ${libQGLViewer_SOURCE_DIR}
+  PATH_SUFFIXES QGLViewer QGLViewer/release)
 target_link_libraries(libQGLViewer INTERFACE ${QGLVIEWER_LIBRARIES})
-add_dependencies(libQGLViewer libQGLViewer_ep-build)
-target_include_directories(libQGLViewer INTERFACE ${QGLVIEWER_INCLUDE_DIR})