Even,
Thanks, I understand it better now and made some advances but I'm still facing
some troubles.
For example, if I do this
papszWarpOptions = CSLSetNameValue(papszWarpOptions, "INIT_DEST", "300" );
psWO->papszWarpOptions = CSLDuplicate(papszWarpOptions);
than it works fine.
However, if I do (remember that I want NaNs)
papszWarpOptions = CSLSetNameValue(papszWarpOptions, "INIT_DEST", "nan" );
than I get zeros again in place of the nodata.
The link you pointed me says
"...or INIT_DEST=NO_DATA: This option forces the destination image to be initialized to the
indicated value (for all bands) or indicates that it should be initialized to the NO_DATA value in
padfDstNoDataReal/padfDstNoDataImag."
So I next tried
papszWarpOptions = CSLSetNameValue(papszWarpOptions, "INIT_DEST", "NO_DATA" );
...
psWO->padfSrcNoDataReal = (double *)
CPLMalloc(psWO->nBandCount*sizeof(double));
psWO->padfSrcNoDataImag = (double *)
CPLMalloc(psWO->nBandCount*sizeof(double));
for (i = 0; i < nBands; i++) {
psWO->padfSrcNoDataReal[i] = 500.;
psWO->padfSrcNoDataImag[i] = 0.0;
GDALSetRasterNoDataValue( GDALGetRasterBand(hDstDS, i+1),
pdfDstNodata[0]);
}
and guess what? bloody zeros again. So I'm not able to get the NaNs (tried with 500 to see if this
solution works)
I tried to see what gdalwarp does ... and another problem. What is this?
gdalwarp -of netCDF -s_srs "+proj=latlong" -t_srs "+proj=utm +zone=29 +datum=WGS84" swath_grid.grd
lixo_utm.grd
Output driver `netCDF' not recognised or does not support
direct output file creation. The following format drivers are configured
and support direct output:
VRT: Virtual Raster
GTiff: GeoTIFF
NITF: National Imagery Transmission Format
HFA: Erdas Imagine Images (.img)
ELAS: ELAS
MEM: In Memory Raster
BMP: MS Windows Device Independent Bitmap
PCIDSK: PCIDSK Database File
ILWIS: ILWIS Raster Map
SGI: SGI Image File Format 1.0
Leveller: Leveller heightfield
Terragen: Terragen heightfield
HDF4Image: HDF4 Dataset
ERS: ERMapper .ers Labelled
JP2ECW: ERMapper JPEG2000
RMF: Raster Matrix Format
RST: Idrisi Raster A.1
INGR: Intergraph Raster
GSBG: Golden Software Binary Grid (.grd)
PNM: Portable Pixmap Format (netpbm)
ENVI: ENVI .hdr Labelled
EHdr: ESRI .hdr Labelled
PAux: PCI .aux Labelled
MFF: Vexcel MFF Raster
MFF2: Vexcel MFF2 (HKV) Raster
BT: VTP .bt (Binary Terrain) 1.3 Format
IDA: Image Data and Analysis
ADRG: ARC Digitized Raster Graphics
SAGA: SAGA GIS Binary Grid (.sdat)
I surely have the netCDF driver. The swath_grid.grd file is in netCDF and the above command works
for the default output type (GeoTiff).
Furthermore, if I ask for the drivers I have (I'm using FWTools here)
gdalwarp --formats
Supported Formats:
VRT (rw+): Virtual Raster
GTiff (rw+v): GeoTIFF
NITF (rw+v): National Imagery Transmission Format
RPFTOC (ro): Raster Product Format TOC format
HFA (rw+v): Erdas Imagine Images (.img)
SAR_CEOS (ro): CEOS SAR Image
CEOS (ro): CEOS Image
JAXAPALSAR (ro): JAXA PALSAR Product Reader (Level 1.1/1.5)
GFF (rov): Ground-based SAR Applications Testbed File Format (.gff)
ELAS (rw+): ELAS
AIG (ro): Arc/Info Binary Grid
AAIGrid (rwv): Arc/Info ASCII Grid
SDTS (ro): SDTS Raster
OGDI (ro): OGDI Bridge
DTED (rwv): DTED Elevation Raster
PNG (rwv): Portable Network Graphics
JPEG (rwv): JPEG JFIF
MEM (rw+): In Memory Raster
JDEM (ro): Japanese DEM (.mem)
GIF (rwv): Graphics Interchange Format (.gif)
BIGGIF (rov): Graphics Interchange Format (.gif)
ESAT (ro): Envisat Image Format
BSB (ro): Maptech BSB Nautical Charts
XPM (rw): X11 PixMap Format
BMP (rw+v): MS Windows Device Independent Bitmap
DIMAP (ro): SPOT DIMAP
AirSAR (ro): AirSAR Polarimetric Image
RS2 (ro): RadarSat 2 XML Product
PCIDSK (rw+v): PCIDSK Database File
PCRaster (rw): PCRaster Raster File
ILWIS (rw+v): ILWIS Raster Map
SGI (rw+): SGI Image File Format 1.0
SRTMHGT (rwv): SRTMHGT File Format
Leveller (rw+): Leveller heightfield
Terragen (rw+): Terragen heightfield
GMT (rw): GMT NetCDF Grid Format
netCDF (rw): Network Common Data Format
HDF4 (ro): Hierarchical Data Format Release 4
HDF4Image (rw+): HDF4 Dataset
ISIS3 (ro): USGS Astrogeology ISIS cube (Version 3)
ISIS2 (ro): USGS Astrogeology ISIS cube (Version 2)
PDS (ro): NASA Planetary Data System
TIL (ro): EarthWatch .TIL
ERS (rw+): ERMapper .ers Labelled
ECW (rw): ERMapper Compressed Wavelets
JP2ECW (rw+): ERMapper JPEG2000
L1B (ro): NOAA Polar Orbiter Level 1b Data Set
FIT (rw): FIT Image
GRIB (ro): GRIdded Binary (.grb)
MrSID (ro): Multi-resolution Seamless Image Database (MrSID)
JP2MrSID (ro): MrSID JPEG2000
RMF (rw+): Raster Matrix Format
WCS (ro): OGC Web Coverage Service
WMS (ro): OGC Web Map Service
MSGN (ro): EUMETSAT Archive native (.nat)
RST (rw+): Idrisi Raster A.1
INGR (rw+): Intergraph Raster
GSAG (rw): Golden Software ASCII Grid (.grd)
GSBG (rw+): Golden Software Binary Grid (.grd)
GS7BG (ro): Golden Software 7 Binary Grid (.grd)
COSAR (ro): COSAR Annotated Binary Matrix (TerraSAR-X)
TSX (ro): TerraSAR-X Product
COASP (ro): DRDC COASP SAR Processor Raster
R (rwv): R Object Data Store
PNM (rw+): Portable Pixmap Format (netpbm)
DOQ1 (ro): USGS DOQ (Old Style)
DOQ2 (ro): USGS DOQ (New Style)
ENVI (rw+v): ENVI .hdr Labelled
EHdr (rw+v): ESRI .hdr Labelled
GenBin (ro): Generic Binary (.hdr Labelled)
PAux (rw+): PCI .aux Labelled
MFF (rw+): Vexcel MFF Raster
MFF2 (rw+): Vexcel MFF2 (HKV) Raster
FujiBAS (ro): Fuji BAS Scanner Image
GSC (ro): GSC Geogrid
FAST (ro): EOSAT FAST Format
BT (rw+): VTP .bt (Binary Terrain) 1.3 Format
LAN (ro): Erdas .LAN/.GIS
CPG (ro): Convair PolGASP
IDA (rw+): Image Data and Analysis
NDF (ro): NLAPS Data Format
EIR (ro): Erdas Imagine Raw
DIPEx (ro): DIPEx
LCP (rov): FARSITE v.4 Landscape File (.lcp)
RIK (ro): Swedish Grid RIK (.rik)
USGSDEM (rw): USGS Optional ASCII DEM (and CDED)
GXF (ro): GeoSoft Grid Exchange Format
HTTP (ro): HTTP Fetching Wrapper
BAG (ro): Bathymetry Attributed Grid
HDF5 (ro): Hierarchical Data Format Release 5
HDF5Image (ro): HDF5 Dataset
NWT_GRD (ro): Northwood Numeric Grid Format .grd/.tab
NWT_GRC (ro): Northwood Classified Grid Format .grc/.tab
ADRG (rw+v): ARC Digitized Raster Graphics
SRP (rov): Standard Raster Product (ASRP/USRP)
BLX (rw): Magellan topo (.blx)
Rasterlite (rw): Rasterlite
WKTRaster (ro): PostGIS WKT Raster driver
SAGA (rw+v): SAGA GIS Binary Grid (.sdat)
Joaquim,
I believe what you see is the expected behaviour.
You must keep in mind that there are 2 notions :
1) nodata value --> setting it is no more than just setting a "tag" on the
raster band. It doesn't change the pixel values by itself as Chaintanya
explained
2) initialization of the pixel data of the target image with a given value
When you use the -dstnodata option, gdalwarp will automagically do both :
1) Set the target nodata value
2) Initialize the target image with that nodata value (remind of removing the
target file if it already exists)
If you specify nothing, then 0 is used to fill the target image but the nodata
tag is not set.
The initialization of the pixel data of the target image is in fact done
through the INIT_DEST warping option. See
http://gdal.org/structGDALWarpOptions.html#0ed77f9917bb96c7a9aabd73d4d06e08
For example, gdalwarp src.tif dst.tif -wo "INIT_DEST=255"
If you specify no INIT_DEST warping option, then gdalwarp uses the dstnodata
value if it's specified with -dstnodata and set it as the INIT_DEST value
too.
I've also tested -dstnodata nan and to my great surprise, it actually works !
However I'm not sure if all applications can deal with the "nan" string put
in the 42113 tag used by GDAL for the Nodata value in TIFF.
So maybe I've not understood what your problem is, but everything seems to
work as expected on my side.
Best regards,
Even
Le Wednesday 12 May 2010 01:37:07 Joaquim Luis, vous avez écrit :
Hi,
Before filling a ticket I would like to ask here if this gdalwarp
behavior is the intended one.
When I convert a grid from geogs to UTM the nodatavalues are filled with
zeros.
I get the expected behaviour if I use the -dstnodata with a numeric
value, but I found no way tom tell it use NaN.
Summary
This puts zeros on the nodata zone, but I don't find it correct as "0"
is not exactly a natural nodata value. For my habits NaN is the natural
no data value.
gdalwarp -s_srs "+proj=latlong" -t_srs "+proj=utm +zone=29 +datum=WGS84"
swath_grid.grd lixo_utm.tiff
Furthermore when I load the " lixo_utm.tiff" in Mirone is does not
recognize a nodata value, whilst if I do this instead
gdalwarp -s_srs "+proj=latlong" -t_srs "+proj=utm +zone=29 +datum=WGS84"
-dstnodata 1 swath_grid.grd lixo_utm.tiff
than "1" is recognized as the nodata. I have not investigated the
metadata to see why the "0" is not set to represent the nodata.
Thanks
Joaquim Luis
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