diff --git a/processing/pre/voronoi_fast.f90 b/processing/pre/voronoi_fast.f90
deleted file mode 100644
index e86dc9bd9..000000000
--- a/processing/pre/voronoi_fast.f90
+++ /dev/null
@@ -1,237 +0,0 @@
-program voronoi
-  use prec, only: pReal, pInt
-
-  implicit none
-
-  logical, dimension(:), allocatable :: seedmap
-  character(len=1024) name, format, format2, N_Digits
-  character choice
-  integer(pInt) a, b, c, ab, abc, abc_Red, N_Seeds, seedPoint, minDistance, myDistance, i, j, k, l, m
-  integer(pInt), dimension(:), allocatable :: seeds, grainMap, visual_Case
-  integer(pInt) coordinates(3)
-  real(pReal), dimension(:), allocatable :: grainEuler
-  real(pReal), parameter :: pi = 3.14159265358979323846264338327950288419716939937510_pReal
-  real(pReal) randomSeed
-
-  print*, '******************************************************************************'
-  print*, '                    Spectral Method Problem Set-up'
-  print*, '******************************************************************************'
-  print*, ''
-  print*, 'generates:'
-  print*, '    * geom file "_GIVEN_NAME_.geom": Geometrical information for solver'
-  print*, '    * material file "material.config": Orientation information for solver'
-  print*, '    * "_GIVEN_NAME_.spectral": combined information for solver'
-  print*, 'optional output:'
-  print*, '    * view file "_GIVEN_NAME_2D.msh": Information for visualization in gmsh'
-  print*, '    * view file "_GIVEN_NAME_3D.msh": Information for visualization in gmsh'
-  print*, ''
-  print*, 'hints:'
-  print*, '    * a+b+c should not exeed 30'
-  print*, '    * file extension is added to given name'
-  print*, ''
-  write(*, '(A)', advance = 'NO') 'Please enter value for a: '
-  read(*, *), a
-  write(*, '(A)', advance = 'NO') 'Please enter value for b: '
-  read(*, *), b
-  write(*, '(A)', advance = 'NO') 'Please enter value for c: '
-  read(*, *), c
-  write(*, '(A)', advance = 'NO') 'Please enter No. of Grains: '
-  read(*, *), N_Seeds
-  write(*, '(A)', advance = 'NO') 'Please enter name of geometry file: '
-  read(*, *), name
-  write(*, '(A)', advance = 'NO') 'Should the visualization files be generated (y/n)? '
-  read(*, *), choice
-
-! calculate No. of digits needed for name of the grains
-  i = 1 + int( log10(real( N_Seeds )))
-  write(N_Digits, *) i
-  N_Digits = adjustl( N_Digits )
-  allocate(grainEuler(3*N_Seeds))
-  
-!write material.config header and add a microstructure entry for every grain
-  open(20, file = trim(name)//('_material.config'))
-  write(20, '(A)'), '<microstructure>'
-  format = '(A, I'//trim(N_Digits)//'.'//trim(N_Digits)//', A)'
-  format2 = '(A, I'//trim(N_Digits)//', A)'
-  do i = 1, N_Seeds
-    write(20, trim(format)), '[Grain', i, ']'
-    write(20, '(A)'), 'crystallite 1'
-    write(20, trim(format2)), '(constituent)  phase 1   texture ', i, '   fraction 1.0'
-  end do
-
-! get random euler angles for every grain, store them in grainEuler and write them to the material.config file
-  format2 = '(A, F10.6, A, F10.6, A, F10.6, A)'
-  write(20, '(/, A)'), '<texture>'
-    do i = 1, N_Seeds
-      call random_number(grainEuler(i*3 -2))
-      call random_number(grainEuler(i*3 -1))
-      call random_number(grainEuler(i*3 -0))
-      grainEuler(i*3 -2) = (grainEuler(i*3 -2))*360
-      grainEuler(i*3 -1) = acos(2.0_pReal*(grainEuler(i*3 -1))-1.0_pReal)*180/pi
-      grainEuler(i*3 -0) = grainEuler(i*3)*360
-      write(20, trim(format)), '[Grain', i, ']'
-      write(20, trim(format2)), '(gauss)  phi1 ', grainEuler(i*3-2), '   Phi ', grainEuler(i*3-1), &
-            &'   Phi2 ', grainEuler(i*3), '   scatter 0   fraction 1'
-    end do
-  close(20)
-  print*, ''
-  print*, 'material config file is written out'
-
-!write header of geom file, should be done before the following change of variables
-  open(20, file = ((trim(name))//'.geom'))
-  write(20, '(A, I2, A, I2, A, I2)'), 'resolution  a ', 2**a, '  b ', 2**b, '  c ', 2**c
-  write(20, '(A, I4, A, I4, A, I4)'), 'dimension   x ', 2**a, '  y ', 2**b, '  z ', 2**c
-  write(20, '(A)'), 'homogenization  1'
-
-!initialize varibles, change values of some numbers for faster execution
-  a = 2**a
-  b = 2**b
-  c = 2**c
-  ab = a * b
-  abc = a * b * c
-  abc_Red = abc -(a-1)*(b-1)*(c-1)
-  format = '(I'//trim(N_Digits)//'.'//trim(N_Digits)//')'
-
-  allocate (seedmap(abc)); seedmap = .false.
-  allocate (seeds(3*N_Seeds))
-  allocate (grainMap(abc))
-  allocate (visual_Case(abc_Red))
-  k = 1
-
-!build array with x-y-z-coordinates of each point
-  do i = 1, abc
-    coordinates(1) = mod((i-1), a) +1
-    coordinates(2) = mod(((i-1)/a), b) +1
-    coordinates(3) = mod(((i-1)/(ab)), c) +1
-    if((coordinates(3) == 1)) then
-      visual_Case(k) = i
-      k = k +1
-    else
-      if((coordinates(2) == 1)) then
-        visual_Case(k) = i
-        k = k +1
-      else
-        if((coordinates(1) == 1)) then
-          visual_Case(k) = i
-          k = k +1
-        else
-        end if
-      end if
-    end if
-  end do
-
-!generate random position of seeds for voronoi tessellation
-  i = 0
-  do while (i /= N_Seeds)
-    call random_number(randomSeed)
-    seedpoint = int(randomSeed*(abc))
-    if (.not.seedmap(seedpoint+1)) then
-      seedmap(seedpoint+1) = .true.
-      seeds(i*3+1) = (mod((seedpoint), a)+1)
-      seeds(i*3+2) = (mod(((seedpoint)/a), b)+1)
-      seeds(i*3+3) = (mod(((seedpoint)/(ab)), c)+1)
-      i = i +1
-    else
-    end if
-  end do
-
-! perform voronoi tessellation and write result to file and to grainMap
-  do i = 1, abc
-    minDistance = a*a+b*b+c*c
-    do j = 1, N_Seeds
-      do k = -1, 1
-        do l = -1, 1
-          do m = -1, 1
-            myDistance = ((mod((i-1), a) +1-seeds(j*3-2)+m*a)**2+&
-                     (mod(((i-1)/a), b) +1-seeds(j*3-1)+l*b)**2+&
-                     (mod(((i-1)/(ab)), c) +1-seeds(j*3-0)+k*c)**2)
-            if (myDistance < minDistance) then
-              minDistance = myDistance
-              grainMap(i) = j
-            end if
-          end do
-        end do
-      end do
-    end do
-    write(20, format), grainMap(i)
-  end do
-  close(20)
-  print*, 'voronoi tesselation finished'
-
-  open(20, file = ((trim(name))//'.spectral'))
-  format = '(tr2, f6.2, tr2, f6.2, tr2, f6.2, I10, I10, I10, I10, a)'
-  do i = 1, abc
-    j = grainMap(i)
-    write(20, trim(format)), grainEuler(j*3-2), grainEuler(j*3-1), grainEuler(j*3), &
-                           &mod((i-1), a)+1, mod(((i-1)/a), b)+1, mod(((i-1)/(ab)), c)+1, &
-                           &j, '   1'
-  end do
-  print*, 'geometry files are written out'
-  
-!write visualization files (in case wanted)
-  if (choice == 'y' .or. choice == 'Y') then
-    print*, 'for more information on gmsh: http://geuz.org/gmsh/'
-
-! write full geometry out
-    open(20, file = ((trim(name))//'_3Dfull.msh'))
-    write(20, '(A, /, A, /, A, /, A, /, I10)'), '$MeshFormat', '2.1 0 8', '$EndMeshFormat', '$Nodes', abc
-    do i = 1, abc
-      write(20, '(I10, I10, I10, I10)'), i, mod((i-1), a) +1, mod(((i-1)/a), b) +1, mod(((i-1)/(ab)), c) +1
-    end do
-    write(20, '(A, /, A, /, I10)'), '$EndNodes', '$Elements', abc
-    do i = 1, abc
-      write(20, '(I10, A, I10, A, I10)'), i, ' 15 2', grainMap(i), ' 2', i
-    end do
-    write(20, '(A)'), '$EndElements'
-    write(20, '(A, /, A, /, A, /, A, /, A, /, A, /, A, /, A, /, I10)'), '$NodeData', '1', '"Grain No."', '1', &
-                                                                 &'0.0', '3', '0', '1', abc
-    do i = 1, abc
-      write(20, '(I10, tr2, I10)'), i, grainMap(i)
-    end do
-    write(20, *), '$EndNodeData'
-    close(20)
- 
-! write 3d skin out
-    open(20, file = ((trim(name))//'_3D.msh'))
-    write(20, '(A, /, A, /, A, /, A, /, I10)'), '$MeshFormat', '2.1 0 8', '$EndMeshFormat', '$Nodes', abc_Red
-    do j = 1, abc_Red
-      i = visual_Case(j)
-      write(20, '(I10, I10, I10, I10)'), i, mod((i-1), a) +1, mod(((i-1)/a), b) +1, mod(((i-1)/(ab)), c) +1
-    end do
-    write(20, '(A, /, A, /, I10)'), '$EndNodes', '$Elements', abc_Red
-    do j = 1, abc_Red
-      i = visual_case(j)
-      write(20, '(I10, A, I10, A, I10)'), i, ' 15 2', grainMap(i), ' 2', i
-    end do
-    write(20, '(A)'), '$EndElements'
-    write(20, '(A, /, A, /, A, /, A, /, A, /, A, /, A, /, A, /, I10)'), '$NodeData', '1', '"Grain No."', '1', &
-                                                                 &'0.0', '3', '0', '1', abc_Red
-    do j = 1, abc_Red
-      i = visual_case(j)
-      write(20, '(I10, tr2, I10)'), i, grainMap(i)
-    end do
-    write(20, *), '$EndNodeData'
-    close(20)
-
-! write 2d geometry out
-    open(20, file = ((trim(name))//'_2D.msh'))
-    write(20, '(A, /, A, /, A, /, A, /, I10)'), '$MeshFormat', '2.1 0 8', '$EndMeshFormat', '$Nodes', ab
-    do i = 1, ab
-      write(20, '(I10, I10, I10, I10)'), i, mod((i-1), a) +1, mod(((i-1)/a), b) +1, mod(((i-1)/(ab)), c) +1
-    end do
-    write(20, '(A, /, A, /, I10)'), '$EndNodes', '$Elements', ab
-    do j = 1, ab
-      write(20, '(I10, A, I10, A, I10)'), j, ' 15 2', grainMap(j), ' 2', j
-    end do
-    write(20, '(A)'), '$EndElements'
-    write(20, '(A, /, A, /, A, /, A, /, A, /, A, /, A, /, A, /, I10)'), '$NodeData', '1', '"Grain No."', &
-                                                    &'1', '0.0', '3', '0', '1', ab
-    do j = 1, ab
-      write(20, '(I10, tr2, I10)'), j, grainMap(j)
-    end do
-    write(20, *), '$EndNodeData'
-    close(20)
-    print*, 'visualization files are written out'
-    else
-  end if
-end program voronoi
diff --git a/processing/pre/voronoi_randomSeeding.f90 b/processing/pre/voronoi_randomSeeding.f90
new file mode 100644
index 000000000..11b97f9d4
--- /dev/null
+++ b/processing/pre/voronoi_randomSeeding.f90
@@ -0,0 +1,80 @@
+!prec.f90 407 2009-08-31 15:09:15Z MPIE\f.roters
+!##############################################################
+ MODULE prec
+!##############################################################
+
+ implicit none
+ 
+!    *** Precision of real and integer variables ***
+ integer, parameter :: pReal = selected_real_kind(15,300)     ! 15 significant digits, up to 1e+-300
+ integer, parameter :: pInt  = selected_int_kind(9)           ! up to +- 1e9
+ integer, parameter :: pLongInt  = 8                          ! should be 64bit
+
+ END MODULE prec
+
+program voronoi
+ use prec, only: pReal, pInt
+ implicit none
+
+ logical, dimension(:), allocatable :: seedmap
+ character(len=1024) filename
+ integer(pInt) a, b, c, N_Seeds, seedpoint, i
+ real(pReal), dimension(:,:), allocatable :: grainEuler, seeds
+ real(pReal), parameter :: pi = 3.14159265358979323846264338327950288419716939937510_pReal
+ real(pReal) randomSeed
+
+ print*, '******************************************************************************'
+ print*, '                    Voronoi description file'
+ print*, '******************************************************************************'
+ print*, ''
+ print*, 'generates:'
+ print*, '    * description file "_GIVEN_NAME_.seeds":'
+ print*, ''
+ write(*, '(A)', advance = 'NO') 'Please enter value for first resolution: '
+ read(*, *), a
+ write(*, '(A)', advance = 'NO') 'Please enter value for second resolution: '
+ read(*, *), b
+ write(*, '(A)', advance = 'NO') 'Please enter value for third resolution: '
+ read(*, *), c
+ write(*, '(A)', advance = 'NO') 'Please enter No. of Grains: '
+ read(*, *), N_Seeds
+ write(*, '(A)', advance = 'NO') 'Please enter name of geometry file: '
+ read(*, *), filename
+
+ allocate (seedmap(a*b*c)); seedmap = .false.  ! logical to store information which position is occupied by a voronoi seed
+ allocate (seeds(N_Seeds,3))
+ allocate (grainEuler(N_Seeds,3))
+  
+ do i=1, N_Seeds
+   call random_number(grainEuler(i,1))
+   call random_number(grainEuler(i,2))
+   call random_number(grainEuler(i,3))
+   grainEuler(i,1) = (grainEuler(i,1))*360                     
+   grainEuler(i,2) = acos(2.0_pReal*(grainEuler(i,2))-1.0_pReal)*180/pi
+   grainEuler(i,3) = grainEuler(i,3)*360
+ enddo
+
+!generate random position of seeds for voronoi tessellation
+ i = 0
+ do while (i /= N_Seeds)
+   call random_number(randomSeed)
+   seedpoint = int(randomSeed*(a*b*c))
+   if (.not.seedmap(seedpoint+1)) then
+     seedmap(seedpoint+1) = .true. 
+     i = i + 1
+     seeds(i,1) = real(mod((seedpoint), a)+1)/real(a, pReal)
+     seeds(i,2) = real(mod(((seedpoint)/a), b)+1)/real(b,pReal)
+     seeds(i,3) = real(mod(((seedpoint)/(a*b)), c)+1)/real(c,pReal)
+   end if
+ end do
+  
+! write description file with orientation and position of each seed
+ open(21, file = trim(filename)//('.seeds'))
+ write(21, '(A, I2, A, I2, A, I2)'), 'resolution  a ', a, '  b ', b, '  c ', c
+ write(21,*), 'grains', N_Seeds
+ do i = 1, n_Seeds
+   write(21, '(6(F10.6,tr2))'),seeds(i,1), seeds(i,2), seeds(i,3),&
+                          grainEuler(i,1), grainEuler(i,2), grainEuler(i,3)              
+ end do
+ close(21)
+end program voronoi
diff --git a/processing/pre/voronoi_small_memory.f90 b/processing/pre/voronoi_small_memory.f90
deleted file mode 100644
index 24cd6eab7..000000000
--- a/processing/pre/voronoi_small_memory.f90
+++ /dev/null
@@ -1,218 +0,0 @@
-program voronoi
-  use prec, only: pReal, pInt
-
-  implicit none
-
-  logical seed
-  character(len=1024) name, format, format2, N_Digits
-  character choice
-  integer(pInt) a, b, c, ab, abc, abc_Red, N_Seeds, seedPoint, minDistance, myDistance, i, j, k, l, m, n, z
-  integer(pInt), dimension(:), allocatable :: seedmap, grainMap, visual_Case
-  integer(pInt) coordinates(3)
-  real(pReal) grainEuler(3)
-  real(pReal), parameter :: pi = 3.14159265358979323846264338327950288419716939937510_pReal
-  real(pReal) randomSeed
-
-  print*, '******************************************************************************'
-  print*, '                    Spectral Method Problem Set-up'
-  print*, '******************************************************************************'
-  print*, ''
-  print*, 'generates:'
-  print*, '    * geometry file "_GIVEN_NAME_.geom": Geometrical information for solver'
-  print*, '    * material file "material.config": Orientation information for solver'
-  print*, 'optional output:'
-  print*, '    * view file "_GIVEN_NAME_2D.msh": Information for visualization in gmsh'
-  print*, '    * view file "_GIVEN_NAME_3D.msh": Information for visualization in gmsh'
-  print*, ''
-  print*, 'hints:'
-  print*, '    * a+b+c should not exeed 30'
-  print*, '    * file extension is added to given name'
-  print*, ''
-  write(*, '(A)', advance = 'NO') 'Please enter value for a: '
-  read(*, *), a
-  write(*, '(A)', advance = 'NO') 'Please enter value for b: '
-  read(*, *), b
-  write(*, '(A)', advance = 'NO') 'Please enter value for c: '
-  read(*, *), c
-  write(*, '(A)', advance = 'NO') 'Please enter No. of Grains: '
-  read(*, *), N_Seeds
-  write(*, '(A)', advance = 'NO') 'Please enter name of geometry file: '
-  read(*, *), name
-  write(*, '(A)', advance = 'NO') 'Should the visualization files be generated (y/n)? '
-  read(*, *), choice
-
-! calculate No. of digits needed for name of the grains
-  i = 1 + int( log10(real( N_Seeds )))
-  write(N_Digits, *) i
-  N_Digits = adjustl( N_Digits )
-
-!write material.config header and add a microstructure entry for every grain
-  open(20, file = trim(name)//('_material.config'))
-  write(20, '(A)'), '<microstructure>'
-  format = '(A, I'//trim(N_Digits)//'.'//trim(N_Digits)//', A)'
-  format2 = '(A, I'//trim(N_Digits)//', A)'
-  do i = 1, N_Seeds
-    write(20, trim(format)), '[Grain', i, ']'
-    write(20, '(A)'), 'crystallite 1'
-    write(20, trim(format2)), '(constituent)  phase 1   texture ', i, '   fraction 1.0'
-  end do
-
-! get random euler angles for every grain, store them in grainEuler and write them to the material.config file
-  format2 = '(A, F10.6, A, F10.6, A, F10.6, A)'
-  write(20, '(/, A)'), '<texture>'
-    do i = 1, N_Seeds
-      call random_number(grainEuler(1))
-      call random_number(grainEuler(2))
-      call random_number(grainEuler(3))
-      grainEuler(1) = (grainEuler(1)) * 360
-      grainEuler(2) = acos(2.0_pReal * (grainEuler(2))-1.0_pReal) * 180/pi
-      grainEuler(3) = grainEuler(3) * 360
-      write(20, trim(format)), '[Grain', i, ']'
-      write(20, trim(format2)), '(gauss)  phi1 ', grainEuler(1), '   Phi ', grainEuler(2), &
-            &'   Phi2 ', grainEuler(3), '   scatter 0   fraction 1'
-    end do
-  close(20)
-  print*, ''
-  print*, 'material config file is written out'
-
-!write header of geometry file, should be done before the following change of variables
-  open(20, file = ((trim(name))//'.geom'))
-  write(20, '(A, I2, A, I2, A, I2)'), 'resolution  a ', 2**a, '  b ', 2**b, '  c ', 2**c
-  write(20, '(A, I4, A, I4, A, I4)'), 'dimension   x ', 2**a, '  y ', 2**b, '  z ', 2**c
-  write(20, '(A)'), 'homogenization  1'
-
-!initialize varibles, change values of some numbers for faster execution
-  a = 2**a
-  b = 2**b
-  c = 2**c
-  ab = a * b
-  abc = a * b * c
-  abc_Red = abc -(a-1)*(b-1)*(c-1)
-  format = '(I'//trim(N_Digits)//'.'//trim(N_Digits)//')'
-
-  allocate (seedmap(3 * N_Seeds)); seedmap = 0
-  allocate (grainMap(abc_Red))
-  allocate (visual_Case(abc_Red))
-  k = 1
-
-!build array with x-y-z-coordinates of each point
-  do i = 1, abc
-    coordinates(1) = mod((i-1), a) +1
-    coordinates(2) = mod(((i-1)/a), b) +1
-    coordinates(3) = mod(((i-1)/(ab)), c) +1
-    if((coordinates(3) == 1)) then
-      visual_Case(k) = i
-      k = k +1
-    else
-      if((coordinates(2) == 1)) then
-        visual_Case(k) = i
-        k = k +1
-      else
-        if((coordinates(1) == 1)) then
-          visual_Case(k) = i
-          k = k +1
-        else
-        end if
-      end if
-    end if
-  end do
-
-!generate random position of seeds for voronoi tessellation
-  i = 0
-  do while (i /= N_Seeds)
-    call random_number(randomSeed)
-    seedpoint = int(randomSeed*(abc))
-    seed = .false.
-    coordinates(1) = mod((seedpoint), a) +1
-    coordinates(2) = mod(((seedpoint)/a), b) +1
-    coordinates(3) = mod(((seedpoint)/(ab)), c) +1
-    do j = 1, i
-      if((coordinates(1) == seedmap(j*3 -2)) .and. &
-        &(coordinates(2) == seedmap(j*3 -1)) .and. &
-        &(coordinates(3) == seedmap(j*3 -0))) seed = .true.
-    end do
-    if (.not.seed) then
-      seedmap(i*3 +1) = coordinates(1)
-      seedmap(i*3 +2) = coordinates(2)
-      seedmap(i*3 +3) = coordinates(3)
-      i = i +1
-    end if
-  end do
-
-! perform voronoi tessellation and write result to file and to grainMap
-  n = 1
-  do i = 1, abc
-    minDistance = a*a+b*b+c*c
-    do j = 1, N_Seeds
-      do k = -1, 1
-        do l = -1, 1
-          do m = -1, 1
-            myDistance = ((mod((i-1), a) +1-seedmap(j*3-2)+m*a)**2+&
-                     (mod(((i-1)/a), b) +1-seedmap(j*3-1)+l*b)**2+&
-                     (mod(((i-1)/(ab)), c) +1-seedmap(j*3-0)+k*c)**2)
-            if (myDistance < minDistance) then
-              minDistance = myDistance
-              z = j
-            end if
-          end do
-        end do
-      end do
-    end do
-    write(20, format), z
-    do k = 1, abc_Red
-      if(visual_Case(k) == i) then
-      grainMap(n) = z
-      n = n +1
-      end if
-    end do
-  end do
-  close(20)
-  print*, 'voronoi tesselation finished'
-  print*, 'geometry file is written out'
-
-!write visualization files (in case wanted)
-  if (choice == 'y' .or. choice == 'Y') then
-    print*, 'for more information on gmsh: http://geuz.org/gmsh/'
-
-! write full geometry out
-    open(20, file = ((trim(name))//'_3D.msh'))
-    write(20, '(A, /, A, /, A, /, A, /, I10)'), '$MeshFormat', '2.1 0 8', '$EndMeshFormat', '$Nodes', abc_Red
-    do j = 1, abc_Red
-      i = visual_Case(j)
-      write(20, '(I10, I10, I10, I10)'), i, mod((i-1), a) +1, mod(((i-1)/a), b) +1, mod(((i-1)/(ab)), c) +1
-    end do
-    write(20, '(A, /, A, /, I10)'), '$EndNodes', '$Elements', abc_Red
-    do j = 1, abc_Red
-      write(20, '(I10, A, I10, A, I10)'), visual_Case(j), ' 15 2', grainMap(j), ' 2', visual_Case(j)
-    end do
-    write(20, '(A)'), '$EndElements'
-    write(20, '(A, /, A, /, A, /, A, /, A, /, A, /, A, /, A, /, I10)'), '$NodeData', '1', '"Grain No."', '1', &
-                                                                 &'0.0', '3', '0', '1', abc_Red
-    do j = 1, abc_Red
-      write(20, '(I10, tr2, I10)'), visual_Case(j), grainMap(j)
-    end do
-    write(20, *), '$EndNodeData'
-    close(20)
-
-! write 2d geometry out
-    open(20, file = ((trim(name))//'_2D.msh'))
-    write(20, '(A, /, A, /, A, /, A, /, I10)'), '$MeshFormat', '2.1 0 8', '$EndMeshFormat', '$Nodes', ab
-    do i = 1, ab
-      write(20, '(I10, I10, I10, I10)'), i, mod((i-1), a) +1, mod(((i-1)/a), b) +1, mod(((i-1)/(ab)), c) +1
-    end do
-    write(20, '(A, /, A, /, I10)'), '$EndNodes', '$Elements', ab
-    do j = 1, ab
-      write(20, '(I10, A, I10, A, I10)'), j, ' 15 2', grainMap(j), ' 2', j
-    end do
-    write(20, '(A)'), '$EndElements'
-    write(20, '(A, /, A, /, A, /, A, /, A, /, A, /, A, /, A, /, I10)'), '$NodeData', '1', '"Grain No."', &
-                                                    &'1', '0.0', '3', '0', '1', ab
-    do j = 1, ab
-      write(20, '(I10, tr2, I10)'), j, grainMap(j)
-    end do
-    write(20, *), '$EndNodeData'
-    close(20)
-    print*, 'visualization files are written out'
-    else
-  end if
-end program voronoi
diff --git a/processing/pre/voronoi_tessellation.f90 b/processing/pre/voronoi_tessellation.f90
new file mode 100644
index 000000000..46370169a
--- /dev/null
+++ b/processing/pre/voronoi_tessellation.f90
@@ -0,0 +1,322 @@
+!prec.f90 407 2009-08-31 15:09:15Z MPIE\f.roters
+!##############################################################
+ MODULE prec
+!##############################################################
+
+ implicit none
+ 
+!    *** Precision of real and integer variables ***
+ integer, parameter :: pReal = selected_real_kind(15,300)     ! 15 significant digits, up to 1e+-300
+ integer, parameter :: pInt  = selected_int_kind(9)           ! up to +- 1e9
+ integer, parameter :: pLongInt  = 8                          ! should be 64bit
+
+ END MODULE prec
+ 
+!IO.f90 693 2010-11-04 18:18:01Z MPIE\c.kords
+!##############################################################
+ MODULE IO   
+!##############################################################
+
+ CONTAINS
+!********************************************************************
+! identifies lines without content
+!********************************************************************
+ pure function IO_isBlank (line)
+
+ use prec, only: pInt
+ implicit none
+
+ character(len=*), intent(in) :: line
+ character(len=*), parameter :: blank = achar(32)//achar(9)//achar(10)//achar(13) ! whitespaces
+ character(len=*), parameter :: comment = achar(35)                               ! comment id '#'
+ integer(pInt) posNonBlank, posComment
+ logical IO_isBlank
+ 
+ posNonBlank = verify(line,blank)
+ posComment  = scan(line,comment)
+ IO_isBlank = posNonBlank == 0 .or. posNonBlank == posComment
+
+ return
+ 
+ endfunction
+
+!********************************************************************
+! read string value at pos from line
+!********************************************************************
+ pure function IO_stringValue (line,positions,pos)
+ 
+ use prec, only: pReal,pInt
+ implicit none
+ 
+ character(len=*), intent(in) :: line
+ integer(pInt), intent(in) :: positions(*),pos
+ character(len=1+positions(pos*2+1)-positions(pos*2)) IO_stringValue
+
+ if (positions(1) < pos) then
+   IO_stringValue = ''
+ else
+   IO_stringValue = line(positions(pos*2):positions(pos*2+1))
+ endif
+ return
+
+ endfunction
+ 
+!********************************************************************
+! read float value at pos from line
+!********************************************************************
+ pure function IO_floatValue (line,positions,pos)
+ 
+ use prec, only: pReal,pInt
+ implicit none
+ 
+ character(len=*), intent(in) :: line
+ integer(pInt), intent(in) :: positions(*),pos
+ real(pReal) IO_floatValue
+
+ if (positions(1) < pos) then
+   IO_floatValue = 0.0_pReal
+ else
+   read(UNIT=line(positions(pos*2):positions(pos*2+1)),ERR=100,FMT=*) IO_floatValue
+ endif
+ return
+100 IO_floatValue = huge(1.0_pReal)
+ return
+
+ endfunction
+ 
+!********************************************************************
+! read int value at pos from line
+!********************************************************************
+ pure function IO_intValue (line,positions,pos)
+ 
+ use prec, only: pReal,pInt
+ implicit none
+ 
+ character(len=*), intent(in) :: line
+ integer(pInt), intent(in) :: positions(*),pos
+ integer(pInt) IO_intValue
+
+ if (positions(1) < pos) then
+   IO_intValue = 0_pInt
+ else
+   read(UNIT=line(positions(pos*2):positions(pos*2+1)),ERR=100,FMT=*) IO_intValue
+ endif
+ return
+100 IO_intValue = huge(1_pInt)
+ return
+
+ endfunction
+ 
+!********************************************************************
+! change character in line to lower case
+!********************************************************************
+ pure function IO_lc (line)
+
+ use prec, only: pInt
+ implicit none
+
+ character (len=*), intent(in) :: line
+ character (len=len(line)) IO_lc
+ integer(pInt) i
+
+ IO_lc = line
+ do i=1,len(line)
+    if(64<iachar(line(i:i)) .and. iachar(line(i:i))<91) IO_lc(i:i)=achar(iachar(line(i:i))+32)
+ enddo
+ return 
+
+ endfunction
+ 
+ !********************************************************************
+! locate at most N space-separated parts in line
+! return array containing number of parts in line and
+! the left/right positions of at most N to be used by IO_xxxVal
+!********************************************************************
+! pure function IO_stringPos (line,N)
+ function IO_stringPos (line,N)
+
+ use prec, only: pReal,pInt
+ implicit none
+
+ character(len=*), intent(in) :: line
+ character(len=*), parameter :: sep=achar(44)//achar(32)//achar(9)//achar(10)//achar(13) ! comma and whitespaces
+ integer(pInt), intent(in) :: N
+ integer(pInt)  left,right
+ integer(pInt) IO_stringPos(1+N*2)
+
+ IO_stringPos = -1
+ IO_stringPos(1) = 0
+ right = 0
+
+ do while (verify(line(right+1:),sep)>0)
+   left  = right + verify(line(right+1:),sep)
+   right = left + scan(line(left:),sep) - 2
+   if ( IO_stringPos(1)<N ) then
+     IO_stringPos(1+IO_stringPos(1)*2+1) = left
+     IO_stringPos(1+IO_stringPos(1)*2+2) = right
+   endif
+   IO_stringPos(1) = IO_stringPos(1)+1
+ enddo
+
+ return
+
+ endfunction
+ 
+END MODULE
+
+program voronoi
+ use prec, only: pReal, pInt
+ use IO
+ implicit none
+
+ logical gotN_Seeds, gotResolution
+ character(len=1024) input_name, output_name, format1, format2, N_Digits, line
+ integer(pInt) a, b, c, N_Seeds, seedPoint, minDistance, myDistance, i, j, k, l, m
+ integer(pInt), dimension(:), allocatable :: grainMap
+ integer(pInt) coordinates(3)
+ integer(pInt), dimension (15) ::  posGeom
+ real(pReal), dimension(:,:), allocatable :: grainEuler, seeds
+ real(pReal), parameter :: pi = 3.14159265358979323846264338327950288419716939937510_pReal
+ real(pReal) scaling
+
+ print*, '******************************************************************************'
+ print*, '                    Spectral Method Problem Set-up'
+ print*, '******************************************************************************'
+ print*, ''
+ print*, 'generates:'
+ print*, '    * geom file "_GIVEN_NAME_.geom": Geometrical information for solver'
+ print*, '    * material file "material.config": Orientation information for solver'
+ print*, '    * "_GIVEN_NAME_.spectral": combined information for solver'
+ print*, ''
+ write(*, '(A)', advance = 'NO') 'Enter filename of input file (extension .seeds): '
+ read(*, *), input_name
+ write(*, '(A)', advance = 'NO') 'Enter filename of output file: '
+ read(*, *), output_name
+  
+ open(20, file = trim(input_name)//('.seeds'), status='old', action='read')
+ rewind(20)
+ do
+   read(20,'(a1024)',END = 100) line
+   if (IO_isBlank(line)) cycle                            ! skip empty lines
+   posGeom = IO_stringPos(line,7)             
+   select case ( IO_lc(IO_StringValue(line,posGeom,1)) )
+     case ('grains')
+       gotN_Seeds = .true.
+       N_Seeds = IO_intValue(line,posGeom,2)
+     case ('resolution')
+       gotResolution = .true.
+       do i = 2,6,2
+         select case (IO_lc(IO_stringValue(line,posGeom,i)))
+           case('a')
+             a = IO_intValue(line,posGeom,i+1)
+           case('b')
+             b = IO_intValue(line,posGeom,i+1)
+           case('c')
+             c = IO_intValue(line,posGeom,i+1)
+         end select
+       enddo
+   end select
+   if (gotN_Seeds .and. gotResolution) exit
+ enddo
+
+ 100 allocate(grainEuler(N_Seeds,3))
+ allocate(Seeds(N_Seeds,3))
+ 
+ print*, 'resolution: ' ,a,b,c
+ write(*, '(A)', advance = 'NO') 'Enter scaling factor: '
+ read(*, *), scaling
+ 
+ a = int(a*scaling)
+ b = int(b*scaling)
+ c = int(c*scaling)
+
+ do i=1, N_seeds
+  read(20,'(a1024)') line
+  if (IO_isBlank(line)) cycle                            ! skip empty lines
+  posGeom = IO_stringPos(line,12)             
+  Seeds(i,1)=IO_floatValue(line,posGeom,1)
+  Seeds(i,2)=IO_floatValue(line,posGeom,2)
+  Seeds(i,3)=IO_floatValue(line,posGeom,3)
+  grainEuler(i,1)=IO_floatValue(line,posGeom,4)
+  grainEuler(i,2)=IO_floatValue(line,posGeom,5)
+  grainEuler(i,3)=IO_floatValue(line,posGeom,6)
+ enddo
+ close(20) 
+ 
+ seeds(:,1) = seeds(:,1)*real(a, pReal)
+ seeds(:,2) = seeds(:,2)*real(b, pReal)
+ seeds(:,3) = seeds(:,3)*real(c, pReal)
+ 
+ allocate (grainMap(a*b*c))
+! calculate No. of digits needed for name of the grains
+  i = 1 + int( log10(real( N_Seeds )))
+  write(N_Digits, *) i
+  N_Digits = adjustl( N_Digits )
+
+!write material.config header and add a microstructure entry for every grain
+  open(20, file = trim(output_name)//('_material.config'))
+  write(20, '(A)'), '<microstructure>'
+  format1 = '(A, I'//trim(N_Digits)//'.'//trim(N_Digits)//', A)'
+  format2 = '(A, I'//trim(N_Digits)//', A)'
+  do i = 1, N_Seeds
+    write(20, trim(format1)), '[Grain', i, ']'
+    write(20, '(A)'), 'crystallite 1'
+    write(20, trim(format2)), '(constituent)  phase 1   texture ', i, '   fraction 1.0'
+  end do
+
+! get random euler angles for every grain, store them in grainEuler and write them to the material.config file
+  format2 = '(6(A, F10.6))'
+  write(20, '(/, A)'), '<texture>'
+    do i = 1, N_Seeds
+      write(20, trim(format1)), '[Grain', i, ']'
+      write(20, trim(format2)), '(gauss)  phi1 ', grainEuler(i,1), '   Phi ', grainEuler(i,2), &
+            &'   Phi2 ', grainEuler(i,3), '   scatter 0   fraction 1'
+    end do
+  close(20)
+  print*, ''
+  print*, 'material config file is written out'
+
+!write header of geom file
+  open(20, file = ((trim(output_name))//'.geom'))
+  write(20, '(A, I2, A, I2, A, I2)'), 'resolution  a ', a, '  b ', b, '  c ', c
+  write(20, '(A, I4, A, I4, A, I4)'), 'dimension   x ', a, '  y ', b, '  z ', c
+  write(20, '(A)'), 'homogenization  1'
+
+!initialize varibles, change values of some numbers for faster execution
+  format1 = '(I'//trim(N_Digits)//'.'//trim(N_Digits)//')'
+
+
+! perform voronoi tessellation and write result to file and to grainMap
+  do i = 1, a*b*c
+    minDistance = a*a+b*b+c*c
+    do j = 1, N_Seeds
+      do k = -1, 1
+        do l = -1, 1
+          do m = -1, 1
+            myDistance = ((mod((i-1), a) +1-seeds(j,1)+m*a)**2+&
+                     (mod(((i-1)/a), b) +1-seeds(j,2)+l*b)**2+&
+                     (mod(((i-1)/(a*b)), c) +1-seeds(j,3)+k*c)**2)
+            if (myDistance < minDistance) then
+              minDistance = myDistance
+              grainMap(i) = j
+            end if
+          end do
+        end do
+      end do
+    end do
+    write(20, format1), grainMap(i)
+  end do
+  close(20)
+  print*, 'voronoi tesselation finished'
+
+  open(20, file = ((trim(output_name))//'.spectral'))
+  format1 = '(3(tr2, f6.2), 3(I10), I10, a)'
+  do i = 1, a*b*c
+    j = grainMap(i)
+    write(20, trim(format1)), grainEuler(j,1), grainEuler(j,2), grainEuler(j,3), &
+                           &mod((i-1), a)+1, mod(((i-1)/a), b)+1, mod(((i-1)/(a*b)), c)+1, &
+                           &j, '   1'
+  end do
+  print*, 'geometry files are written out'
+ 
+end program voronoi