No subject

under HDF & HDF-EOS Utilities is a path to download the 
ECS project version of GCTP which has:
  ISINUSFOR.C 
  ISINUSINV.C

"Integerized Sinusoidal Library Functions - library routines to 
 perform mapping to and from the Integerized Sinusoidal.  These  
 functions perform the mapping from projection coordinates (x/y)  
 to the geographic coordinates (longitude/latitude)."

from web page:
"In developing HDF-EOS, several bugs were identified and 
 corrected in the GCTP code. Since the USGS has 
 dropped support for the code, the ECS project now 
 maintains its own custom version of the library source. The 
 ECS version of GCTP incorporates all the bug fixes and a 
 new projection (the Integerized Sinusoidal Projection; 
 projection code 99)."

Hope this helps.

John



-----Original Message-----
From: Markus Neteler [mailto:neteler at itc.it]
Sent: Friday, August 01, 2003 9:49 AM
To: grass5 developers list
Subject: [GRASS5] GRASS and MODIS V004 SIN projection?


Dear developers,

to process MODIS V004 data which are projected in SIN (Sinusoidal)
projection, I would like to know which projection to choose
in GRASS:

fouc_s:Foucaut Sinusoidal
gn_sinu:General Sinusoidal Series
sinu:Sinusoidal (Sanson-Flamsteed)

I assume that it is none of above: The MODIS metadata refer
to GCTP_SNSOID. In the GCTP there are two files:
gctp/sinfor.c
gctp/sininv.c

"NAME                            SINUSOIDAL

PURPOSE:        Transforms input longitude and latitude to Easting and
                Northing for the Sinusoidal projection.  The
                longitude and latitude must be in radians.  The Easting
                and Northing values will be returned in meters.
"

The required parameters for GCTP_SNSOID are:
"static double lon_center;       /* Center longitude (projection center) */
static double R;                /* Radius of the earth (sphere)         */
static double false_easting;    /* x offset in meters                   */
static double false_northing;   /* y offset in meters                   */
"

The MODIS V004 LST metadata say (excerpt from
 http://mpa.itc.it/markus/modis/MOD11A1.A2000055.h18v04.004.2002355023354.StructMetadata.0 
):
                UpperLeftPointMtrs=(0.000000,5559752.598833)
                LowerRightMtrs=(1111950.519767,4447802.079066)
                Projection=GCTP_SNSOID
                ProjParams=(6371007.181000,0,0,0,0,0,0,0,86400,0,0,0,0)


The HDFEOS software interprets above:
http://asl.umbc.edu/pub/motteler/hdf/hdfeos/hdfeos/src/GDapi.c
intn
GDprojinfo(int32 gridID, int32 * projcode, int32 * zonecode,
	   int32 * spherecode, float64 projparm[])

-> projparm[0] = 6371007.181000
-> projparm[8] = 86400

Probably it's easy to define this in GRASS?

Thanks in advance,

 Markus

_______________________________________________
grass5 mailing list
grass5 at grass.itc.it
http://grass.itc.it/mailman/listinfo/grass5