On Tue, Mar 27, 2012 at 1:17 PM, Ripsime Khachatryan <kul...@mail.ru> wrote:
> Hi all
>
>
> I would like to asks if anybody calculated the vegetation index using OpenMP,
> and can anybody give me detailed information how to do that.
> I performed the same operation using MPI, so I am familiar with calculation.
>
Below is a patch for i.vi (GRASS 7). On a quad-core system, there is
no real speedup, only (combined) CPU time increases...
Markus M
start of patch -->
Index: imagery/i.vi/Makefile
===================================================================
--- imagery/i.vi/Makefile (revision 51167)
+++ imagery/i.vi/Makefile (working copy)
@@ -5,6 +5,9 @@
LIBES = $(RASTERLIB) $(GISLIB) $(MATHLIB)
DEPENDENCIES = $(RASTERDEP) $(GISDEP)
+EXTRA_LIBS = $(OMPLIB)
+EXTRA_CFLAGS = $(OMPCFLAGS)
+
include $(MODULE_TOPDIR)/include/Make/Module.make
Index: imagery/i.vi/main.c
===================================================================
--- imagery/i.vi/main.c (revision 51167)
+++ imagery/i.vi/main.c (working copy)
@@ -252,6 +252,10 @@
|| !(input6->answer) || !(input7->answer)) )
G_fatal_error(_("gvi index requires blue, green, red, nir, chan5 and
chan7 maps"));
+ /* init variables */
+ infd_redchan = infd_nirchan = infd_greenchan = -1;
+ infd_bluechan = infd_chan5chan = infd_chan7chan = -1;
+
infd_redchan = Rast_open_old(redchan, "");
data_type_redchan = Rast_map_type(redchan, "");
inrast_redchan = Rast_allocate_buf(data_type_redchan);
@@ -296,13 +300,6 @@
/* Process pixels */
for (row = 0; row < nrows; row++)
{
- DCELL d_bluechan;
- DCELL d_greenchan;
- DCELL d_redchan;
- DCELL d_nirchan;
- DCELL d_chan5chan;
- DCELL d_chan7chan;
-
G_percent(row, nrows, 2);
/* read input maps */
@@ -322,9 +319,18 @@
if (chan7chan) {
Rast_get_row(infd_chan7chan,inrast_chan7chan,row,data_type_chan7chan);
}
+
/* process the data */
+ #pragma omp parallel for schedule (static)
for (col = 0; col < ncols; col++)
{
+ DCELL d_bluechan;
+ DCELL d_greenchan;
+ DCELL d_redchan;
+ DCELL d_nirchan;
+ DCELL d_chan5chan;
+ DCELL d_chan7chan;
+
switch(data_type_redchan){
case CELL_TYPE:
d_redchan = (double) ((CELL *) inrast_redchan)[col];
<-- end of patch
>
>
> Thanks in advance for any help.
>
> Regards,
> Ripsime
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