diff --git a/Superbuild/CMake/External_boost.cmake b/Superbuild/CMake/External_boost.cmake
index 86bb2fdd8d527b25562f91bd643c6e6a6f8051e9..8bbd5e5cd755773b2e6ca17cbfd08038a2a53f1c 100644
--- a/Superbuild/CMake/External_boost.cmake
+++ b/Superbuild/CMake/External_boost.cmake
@@ -15,7 +15,6 @@ if(USE_SYSTEM_BOOST)
   # Required
   find_package ( Boost
     1.35.0
-    REQUIRED
     )
   # Optional components
   find_package ( Boost
diff --git a/Superbuild/CMake/External_curl.cmake b/Superbuild/CMake/External_curl.cmake
index 0795fcedc5e5936856ec494d8bb899b15f703b36..d90f9ad245311eccd539d24193798bbfcf72eea6 100644
--- a/Superbuild/CMake/External_curl.cmake
+++ b/Superbuild/CMake/External_curl.cmake
@@ -6,7 +6,7 @@ set(__EXTERNAL_${proj}__ 1)
 message(STATUS "Setup cURL ...")
 
 if(USE_SYSTEM_CURL)
-  find_package ( CURL REQUIRED )
+  find_package ( CURL )
   add_custom_target(${proj})
   message(STATUS "  Using cURL system version")
 else()
diff --git a/Superbuild/CMake/External_expat.cmake b/Superbuild/CMake/External_expat.cmake
index fc84617198c374a2e3d778a2ae2f1803d955ad4d..66305893ad260b865a273ee2d11e8ba939122ec4 100644
--- a/Superbuild/CMake/External_expat.cmake
+++ b/Superbuild/CMake/External_expat.cmake
@@ -6,7 +6,7 @@ set(__EXTERNAL_${proj}__ 1)
 message(STATUS "Setup expat ...")
 
 if(USE_SYSTEM_EXPAT)
-  find_package ( EXPAT REQUIRED )
+  find_package ( EXPAT )
   add_custom_target(${proj})
   message(STATUS "  Using expat system version")
 else()
diff --git a/Superbuild/CMake/External_fftw.cmake b/Superbuild/CMake/External_fftw.cmake
index 8dc510b3bd23450bbda480347c58ec424a1d0ed9..f1e13fe9f264ca2a8d5804ad55ad8a5bc7d17f80 100644
--- a/Superbuild/CMake/External_fftw.cmake
+++ b/Superbuild/CMake/External_fftw.cmake
@@ -7,7 +7,7 @@ message(STATUS "Setup FFTW ...")
 
 if(USE_SYSTEM_FFTW)
   # TODO : use ITK's FindFFTW
-  #find_package ( FFTW REQUIRED )
+  #find_package ( FFTW )
   add_custom_target(${proj})
   message(STATUS "  Using FFTW system version")
 else()
diff --git a/Superbuild/CMake/External_gdal.cmake b/Superbuild/CMake/External_gdal.cmake
index 45a080455b96af9fb025e297d67b7ca866f7ae20..4c5796f19119f73950f2e0d88586c4885f611437 100644
--- a/Superbuild/CMake/External_gdal.cmake
+++ b/Superbuild/CMake/External_gdal.cmake
@@ -6,7 +6,7 @@ set(__EXTERNAL_${proj}__ 1)
 message(STATUS "Setup GDAL...")
 
 if(USE_SYSTEM_GDAL)
-  find_package ( GDAL REQUIRED )
+  find_package ( GDAL )
   add_custom_target(${proj})
   message(STATUS "  Using GDAL system version")
 else()
diff --git a/Superbuild/CMake/External_geos.cmake b/Superbuild/CMake/External_geos.cmake
index 56dba368dfa889f66a60e9da3024eaf1dec7e742..551a838a030af6642ebe7cf99e53ce69579650d3 100644
--- a/Superbuild/CMake/External_geos.cmake
+++ b/Superbuild/CMake/External_geos.cmake
@@ -7,7 +7,7 @@ message(STATUS "Setup GEOS ...")
 
 if(USE_SYSTEM_GEOS)
   # TODO : FindGEOS.cmake
-  #find_package ( GEOS REQUIRED )
+  #find_package ( GEOS )
   add_custom_target(${proj})
   message(STATUS "  Using GEOS system version")
 else()
diff --git a/Superbuild/CMake/External_geotiff.cmake b/Superbuild/CMake/External_geotiff.cmake
index 15a8ed76983c39b3892ee2c9477d2bd129759c05..b282e7edb9bf1f8a25b6b6aaccb908e0ee2a6023 100644
--- a/Superbuild/CMake/External_geotiff.cmake
+++ b/Superbuild/CMake/External_geotiff.cmake
@@ -6,7 +6,7 @@ set(__EXTERNAL_${proj}__ 1)
 message(STATUS "Setup libgeotiff...")
 
 if(USE_SYSTEM_GEOTIFF)
-  find_package ( GeoTIFF REQUIRED )
+  find_package ( GeoTIFF )
   add_custom_target(${proj})
   message(STATUS "  Using libgeotiff system version")
 else()
diff --git a/Superbuild/CMake/External_itk.cmake b/Superbuild/CMake/External_itk.cmake
index 4fcd1f9df2e1cbaff31def5f725546fc2183f5dd..62e0a7fd5684e1b9620a8238f42dafa1eded8332 100644
--- a/Superbuild/CMake/External_itk.cmake
+++ b/Superbuild/CMake/External_itk.cmake
@@ -6,7 +6,7 @@ set(__EXTERNAL_${proj}__ 1)
 message(STATUS "Setup ITK...")
 
 if(USE_SYSTEM_ITK)
-  find_package ( ITK REQUIRED )
+  find_package ( ITK )
   add_custom_target(${proj})
   message(STATUS "  Using ITK system version")
 else()
diff --git a/Superbuild/CMake/External_jpeg.cmake b/Superbuild/CMake/External_jpeg.cmake
index 13f43c0aa5c56384f32f003b883673233316b5a4..045c634226ada31cd0e4a63ab9221a77064db458 100644
--- a/Superbuild/CMake/External_jpeg.cmake
+++ b/Superbuild/CMake/External_jpeg.cmake
@@ -6,7 +6,7 @@ set(__EXTERNAL_${proj}__ 1)
 message(STATUS "Setup libjpeg...")
 
 if(USE_SYSTEM_JPEG)
-  find_package ( JPEG REQUIRED )
+  find_package ( JPEG )
   add_custom_target(${proj})
   message(STATUS "  Using libjpeg system version")
 else()
diff --git a/Superbuild/CMake/External_libkml.cmake b/Superbuild/CMake/External_libkml.cmake
index da5f8769094b688b4af07be49d8ce2ba1f1700d3..f28cc8c3e04e5a8a52d895b98496d69f9b38626e 100644
--- a/Superbuild/CMake/External_libkml.cmake
+++ b/Superbuild/CMake/External_libkml.cmake
@@ -6,7 +6,7 @@ set(__EXTERNAL_${proj}__ 1)
 message(STATUS "Setup libKML ...")
 
 if(USE_SYSTEM_LIBKML)
-  find_package ( LibKML REQUIRED )
+  find_package ( LibKML )
   add_custom_target(${proj})
   message(STATUS "  Using libKML system version")
 else()
diff --git a/Superbuild/CMake/External_muparser.cmake b/Superbuild/CMake/External_muparser.cmake
index 5491da27bb5f695507edd7a1333bc1588583bc43..ad0fff479d5da72751ac6f501b64ff68b9b089b4 100644
--- a/Superbuild/CMake/External_muparser.cmake
+++ b/Superbuild/CMake/External_muparser.cmake
@@ -6,7 +6,7 @@ set(__EXTERNAL_${proj}__ 1)
 message(STATUS "Setup muParser ...")
 
 if(USE_SYSTEM_MUPARSER)
-  find_package ( MUPARSER REQUIRED )
+  find_package ( MUPARSER )
   add_custom_target(${proj})
   message(STATUS "  Using muParser system version")
 else()
diff --git a/Superbuild/CMake/External_muparserx.cmake b/Superbuild/CMake/External_muparserx.cmake
index 2aaadcf15e9ddab8c7509a833138c37070f63617..fac187ce4b0296fdd088c5a8fe01322f18b02d13 100644
--- a/Superbuild/CMake/External_muparserx.cmake
+++ b/Superbuild/CMake/External_muparserx.cmake
@@ -6,7 +6,7 @@ set(__EXTERNAL_${proj}__ 1)
 message(STATUS "Setup muParserX ...")
 
 if(USE_SYSTEM_MUPARSERX)
-  find_package ( MUPARSERX REQUIRED )
+  find_package ( MUPARSERX )
   add_custom_target(${proj})
   message(STATUS "  Using muParserX system version")
 else()
diff --git a/Superbuild/CMake/External_opencv.cmake b/Superbuild/CMake/External_opencv.cmake
index d76d4dfa69b94e7e7741ebfbe6a14831c6197ddb..623bc834b8edb4a8ade225050462f8ab21d09229 100644
--- a/Superbuild/CMake/External_opencv.cmake
+++ b/Superbuild/CMake/External_opencv.cmake
@@ -6,7 +6,7 @@ set(__EXTERNAL_${proj}__ 1)
 message(STATUS "Setup OpenCV...")
 
 if(USE_SYSTEM_OPENCV)
-  find_package ( OpenCV REQUIRED )
+  find_package ( OpenCV )
   add_custom_target(${proj})
   message(STATUS "  Using OpenCV system version")
 else()
diff --git a/Superbuild/CMake/External_openjpeg.cmake b/Superbuild/CMake/External_openjpeg.cmake
index 44ae71e618b1d533c7d1724fa0e2b1603cec2096..15deda83803cfddd3e1c547b0a37efe45ae1d5e8 100644
--- a/Superbuild/CMake/External_openjpeg.cmake
+++ b/Superbuild/CMake/External_openjpeg.cmake
@@ -7,7 +7,7 @@ message(STATUS "Setup OpenJpeg...")
 
 if(USE_SYSTEM_OPENJPEG)
   # TODO : FindOpenJPEG.cmake
-  # find_package ( OpenJPEG REQUIRED )
+  # find_package ( OpenJPEG )
   add_custom_target(${proj})
   message(STATUS "  Using OpenJpeg system version")
 else()
diff --git a/Superbuild/CMake/External_openthreads.cmake b/Superbuild/CMake/External_openthreads.cmake
index 936e38de94afb6f660c08de4fecb66bc182a1ddf..71db8cd228e5226a7ebf7bc1a2e15fd710228352 100644
--- a/Superbuild/CMake/External_openthreads.cmake
+++ b/Superbuild/CMake/External_openthreads.cmake
@@ -10,7 +10,7 @@ set(USE_SYSTEM_OPENTHREADS OFF)
 endif()
 
 if(USE_SYSTEM_OPENTHREADS)
-  find_package ( OpenThreads REQUIRED )
+  find_package ( OpenThreads )
   add_custom_target(${proj})
   message(STATUS "  Using OpenThread system version")
 else()
diff --git a/Superbuild/CMake/External_ossim.cmake b/Superbuild/CMake/External_ossim.cmake
index 3d7bbc34b1e8eecb2354e2ecda82dff31c317ac8..8b0b252994652330b25335af7c5560ebb455710a 100644
--- a/Superbuild/CMake/External_ossim.cmake
+++ b/Superbuild/CMake/External_ossim.cmake
@@ -14,7 +14,7 @@ message(STATUS "Setup Ossim...")
 ADD_SYSTEM_LOCATION(PROJECT ${proj} VARIABLES ${proj}_LIBRARY ${proj}_INCLUDE_DIR)
 
 if(USE_SYSTEM_OSSIM)
-  find_package ( Ossim REQUIRED )
+  find_package ( Ossim )
   add_custom_target(${proj})
   message(STATUS "  Using OSSIM system version")
 else()
diff --git a/Superbuild/CMake/External_pcre.cmake b/Superbuild/CMake/External_pcre.cmake
index 8e6f315643a65547b581f03dcac63c0e698254bc..b81661e42d88bf0a4d7a46181a195fc722e9f514 100644
--- a/Superbuild/CMake/External_pcre.cmake
+++ b/Superbuild/CMake/External_pcre.cmake
@@ -7,7 +7,7 @@ message(STATUS "Setup pcre...")
 
 if(USE_SYSTEM_PCRE)
   # TODO : FindPCRE.cmake
-  # find_package ( PCRE REQUIRED )
+  # find_package ( PCRE )
   add_custom_target(${proj})
   message(STATUS "  Using pcre system version")
 else()
diff --git a/Superbuild/CMake/External_png.cmake b/Superbuild/CMake/External_png.cmake
index 44bfb2b33f2df7251771f1227824b921d453617f..b3b41bd37b406b357fd10b61f01706bc150dc2ae 100644
--- a/Superbuild/CMake/External_png.cmake
+++ b/Superbuild/CMake/External_png.cmake
@@ -6,7 +6,7 @@ set(__EXTERNAL_${proj}__ 1)
 message(STATUS "Setup libpng...")
 
 if(USE_SYSTEM_PNG)
-  find_package ( PNG REQUIRED )
+  find_package ( PNG )
   add_custom_target(${proj})
   message(STATUS "  Using libpng system version")
 else()
diff --git a/Superbuild/CMake/External_proj.cmake b/Superbuild/CMake/External_proj.cmake
index 06f121ee04a8b4e92db4d5ddbd1ec5a17d7172ca..78e1cf4317f8fd9cadc6e7a2400e8442d46458c6 100644
--- a/Superbuild/CMake/External_proj.cmake
+++ b/Superbuild/CMake/External_proj.cmake
@@ -7,7 +7,7 @@ message(STATUS "Setup Proj.4 ...")
 
 if(USE_SYSTEM_PROJ)
   # TODO : FindPROJ.cmake
-  #find_package ( PROJ REQUIRED )
+  #find_package ( PROJ )
   add_custom_target(${proj})
   message(STATUS "  Using Proj4 system version")
 else()
diff --git a/Superbuild/CMake/External_qt4.cmake b/Superbuild/CMake/External_qt4.cmake
index 1c306f13ca69120d4aa09e6b1fc570d2f5ad9736..b7010767512ac8e75fcb2e0170255f9306457657 100644
--- a/Superbuild/CMake/External_qt4.cmake
+++ b/Superbuild/CMake/External_qt4.cmake
@@ -6,7 +6,7 @@ set(__EXTERNAL_${proj}__ 1)
 message(STATUS "Setup Qt4 ...")
 
 if(USE_SYSTEM_QT4)
-  find_package ( QT4 REQUIRED )
+  find_package ( QT4 )
   add_custom_target(${proj})
   message(STATUS "  Using Qt4 system version")
 else()
diff --git a/Superbuild/CMake/External_sqlite.cmake b/Superbuild/CMake/External_sqlite.cmake
index f0522da05ad827c05cdfcc5391216932d886eb27..357ed98387dbe382bad2f246c0f9e215602a7683 100644
--- a/Superbuild/CMake/External_sqlite.cmake
+++ b/Superbuild/CMake/External_sqlite.cmake
@@ -7,7 +7,7 @@ message(STATUS "Setup SQLite...")
 
 if(USE_SYSTEM_SQLITE)
   # TODO
-  #find_package ( SQLite REQUIRED )
+  #find_package ( SQLite )
   add_custom_target(${proj})
   message(STATUS "  Using SQLite system version")
 else()
diff --git a/Superbuild/CMake/External_swig.cmake b/Superbuild/CMake/External_swig.cmake
index eca35778a069234466af303bed5b08309ed06baf..5f5104637148178741dbdf9a6e6d620772fb8470 100644
--- a/Superbuild/CMake/External_swig.cmake
+++ b/Superbuild/CMake/External_swig.cmake
@@ -6,7 +6,7 @@ set(__EXTERNAL_${proj}__ 1)
 message(STATUS "Setup swig...")
 
 if(USE_SYSTEM_SWIG)
-  find_package ( SWIG REQUIRED )
+  find_package ( SWIG )
   add_custom_target(${proj})
   message(STATUS "  Using swig system version")
 else()
diff --git a/Superbuild/CMake/External_tiff.cmake b/Superbuild/CMake/External_tiff.cmake
index 5b56aea5187b8b2444dde661a36be5cdbffa777d..f54384fa1b01d1614f95a3b4c0794eaa22cb8b94 100644
--- a/Superbuild/CMake/External_tiff.cmake
+++ b/Superbuild/CMake/External_tiff.cmake
@@ -10,7 +10,7 @@ message(STATUS "Setup libtiff...")
 #ADD_SYSTEM_PREFIX(PROJECT ${proj})
 
 if(USE_SYSTEM_TIFF)
-  find_package ( TIFF REQUIRED )
+  find_package ( TIFF )
   add_custom_target(${proj})
   message(STATUS "  Using libtiff system version")
 else()
diff --git a/Superbuild/CMake/External_tinyxml.cmake b/Superbuild/CMake/External_tinyxml.cmake
index e02233113006beb22937962b359f2dd5a99b287a..d39fc92a925de32956bd6dfd41b18cb81261af74 100644
--- a/Superbuild/CMake/External_tinyxml.cmake
+++ b/Superbuild/CMake/External_tinyxml.cmake
@@ -6,7 +6,7 @@ set(__EXTERNAL_${proj}__ 1)
 message(STATUS "Setup TinyXML ...")
 
 if(USE_SYSTEM_TINYXML)
-  find_package ( TinyXML REQUIRED )
+  find_package ( TinyXML )
   add_custom_target(${proj})
   message(STATUS "  Using TinyXML system version")
 else()
diff --git a/Superbuild/CMake/External_zlib.cmake b/Superbuild/CMake/External_zlib.cmake
index a730efae00b594f67a5319a1759fa54bee6ffcb0..dca205566333bae9b51e4be2ce0c310213860f6c 100644
--- a/Superbuild/CMake/External_zlib.cmake
+++ b/Superbuild/CMake/External_zlib.cmake
@@ -8,7 +8,7 @@ message(STATUS "Setup Zlib ...")
 ADD_SYSTEM_PREFIX(PROJECT ${proj} CMAKE_ALIAS ZLIB_ROOT)
 
 if(USE_SYSTEM_ZLIB)
-  find_package(ZLIB REQUIRED)
+  find_package(ZLIB)
   add_custom_target(${proj})
   message(STATUS "  Using Zlib system version")
 else()