[gradsusr] Geotiffs in Grads
Yaqiang Wang
yaqiang.wang at gmail.com
Wed Dec 22 07:22:36 EST 2010
Aother possible is your tfw file is correct with a specail projection
setting. The point is to know the projection parameters.
On Wed, Dec 22, 2010 at 3:42 PM, Yaqiang Wang <yaqiang.wang at gmail.com> wrote:
> In fact, your data is tif not geotif. The tfw file is world file for
> geolocation of the image, but it's not the projection parameters.
>
> Your 'tfw' file obviously is not correct with too big x and y scales.
> I ajust the x and y scales to 0.017 and the geolocated figure is
> attached. It's still not correct, because I don't know the exactly the
> geo-location of the image. If you know, you can adjust it to the right
> location.
>
> The description of world file is following:
> World File
> Images are stored as raster data, where each cell in the image has a
> row and column number. In order to display images in real-world
> coordinates, it is necessary to establish an image-to-world
> transformation that converts the image coordinates to real-world
> coordinates. This transformation information is typically stored with
> the image.
> This information was stored in a separate ASCII file. This file is
> generally referred to as the world file, since it contains the
> real-world transformation information used by the image. World files
> can be created with any editor. They can also be created using
> MeteoInfo.
> It’s easy to identify the world file which should accompany an image
> file. The first and third characters of the image file’s suffix and a
> final "w" are used for the world file suffix. Therefore, for
> ‘mytown.tif’, the world file would be ‘mytown.tfw’. For
> ‘redlands.gif’, its world file would be ‘redlands.gfw’.
> The contents of the world file will look something like this:
>
> 20.17541308822119 -A
> 0.00000000000000 -D
> 0.00000000000000 -B
> -20.17541308822119 -E
> 424178.11472601280548 -C
> 4313415.90726399607956 -F
>
> When this file is present, it performs the image-to-world transformation.
> A = x-scale; dimension of a pixel in map units in x direction
> B, D = rotation terms
> C, F = translation terms; x,y map coordinates of the center of the
> upper-left pixel
> E = negative of y-scale; dimension of a pixel in map units in y direction
>
> Note: The y-scale (E) is negative because the origins of an image and
> a geographic coordinate system are different. The origin of an image
> is located in the upper-left corner, whereas the origin of the map
> coordinate system is located in the lower-left corner. Row values in
> the image increase from the origin downward, while y-coordinate values
> in the map increase from the origin upward.
>
>
> On Wed, Dec 22, 2010 at 11:44 AM, Nick Heath <nkh09 at fsu.edu> wrote:
>> Hi,
>>
>> Thanks for the information. I have attached the geotiff file that I used to create the ASCII grid format along with the world file that accompanied it. Thank you all again for the help.
>>
>> -Nick
>>
>> ----- Original Message -----
>> From: Yaqiang Wang <yaqiang.wang at gmail.com>
>> Date: Tuesday, December 21, 2010 7:37 pm
>> Subject: Re: [gradsusr] Geotiffs in Grads
>> To: GrADS Users Forum <gradsusr at gradsusr.org>
>>
>>> Hi Nick,
>>>
>>> I have checked your data. "20100424_160000.asc" is ESRI ASCII Grid
>>> format data which could be supported in many GIS software. The problem
>>> is I don't know the projection information of the data which is not
>>> longitude/latitude coordinate, and the ESRI ASCII Grid format has no
>>> information of the projection. The projection information should has
>>> been included in the geotiff file.
>>>
>>> On Wed, Dec 22, 2010 at 3:54 AM, Nick Heath <nkh09 at fsu.edu> wrote:
>>> > Hi,
>>> >
>>> > Thank you both for the help! I have found a way to convert the
>>> geotiffs into gridded data. I have attached 2 of the output files
>>> after the conversion (I tried two different formats). Now, I am a
>>> bit lost on how to make a control file with this data as I am used
>>> to working with Grib or netcdf. Maybe someone could help? In the
>>> .dat file, I believe the 3 columns are Y,X, and either 0 (no oil)
>>> or 16777215 for oil. I am not sure why the converter picked that
>>> number. Thanks an advance for the help!
>>> >
>>> > -Nick
>>> >
>>> > ----- Original Message -----
>>> > From: Jennifer Adams <jma at cola.iges.org>
>>> > Date: Tuesday, December 21, 2010 10:48 am
>>> > Subject: Re: [gradsusr] Geotiffs in Grads
>>> > To: GrADS Users Forum <gradsusr at gradsusr.org>
>>> >
>>> >> Hi, Nick --
>>> >> What you are asking for is a 'dtype geotiff' which does not exist
>>> >> in
>>> >> GrADS. Turning the information in a geotiff file into a grid of
>>> >> values
>>> >> that you can analyze with GrADS is a job for customized stand-alone
>>> >>
>>> >> code. You may find some useful utilities to help you get started in
>>> >>
>>> >> the libgeotiff distribution.
>>> >> --Jennifer
>>> >>
>>> >>
>>> >> On Dec 21, 2010, at 10:29 AM, Nick Heath wrote:
>>> >>
>>> >> > Hi everyone,
>>> >> >
>>> >> > I am working with oil spill data, and I need a way to display the
>>> >>
>>> >> > oil in my model. I have geotiffs of the oil locations and I was
>>> >> > wondering if there is any way to read those into Grads. I also
>>> >> have
>>> >> > the locations in .gif files. If that is not possible, does
>>> >> anyone
>>> >> > have any good ideas of how I could make a "blob" of oil that I
>>> >> could
>>> >> > apply equations to (such as a wind drift to watch how it moved
>>> >> > through time)?
>>> >> >
>>> >> > Here is the config of the Grads I'm using:
>>> >> >
>>> >> > Config: v2.0.a8 little-endian readline printim grib2 netcdf
>>> hdf4-
>>> >> sds
>>> >> > hdf5 opendap-grids,stn geotiff shapefile
>>> >> > Grid Analysis and Display System (GrADS) Version 2.0.a8
>>> >> > Copyright (c) 1988-2010 by Brian Doty and the
>>> >> > Institute for Global Environment and Society (IGES)
>>> >> > This program is distributed WITHOUT ANY WARRANTY
>>> >> > See file COPYRIGHT for more information.
>>> >> >
>>> >> > Built Fri Mar 26 10:24:10 EDT 2010 for x86_64-unknown-linux-gnu
>>> >> >
>>> >> > This version of GrADS has been configured with the following
>>> >> options:> o Built on a LITTLE ENDIAN machine
>>> >> > o Athena Widget GUI DISABLED
>>> >> > o Command line editing ENABLED
>>> >> > http://tiswww.case.edu/php/chet/readline/rltop.html
>>> >> > o printim command for image output ENABLED
>>> >> > http://www.zlib.net
>>> >> > http://www.libpng.org/pub/png/libpng.html
>>> >> > http://www.libgd.org/Main_Page
>>> >> > o GRIB2 interface ENABLED
>>> >> > http://www.ijg.org
>>> >> > http://www.ece.uvic.ca/~mdadams/jasper
>>> >> > http://www.nco.ncep.noaa.gov/pmb/codes/GRIB2
>>> >> > g2clib-1.1.8
>>> >> > o NetCDF interface ENABLED
>>> >> > http://www.unidata.ucar.edu/software/netcdf
>>> >> > netcdf 4.1.1-rc2 of Mar 23 2010 09:31:58 $
>>> >> > o OPeNDAP gridded data interface ENABLED
>>> >> > o OPeNDAP station data interface ENABLED
>>> >> > http://iges.org/grads/gadoc/supplibs.html
>>> >> > libgadap 2.0
>>> >> > o HDF4 and HDF5 interfaces ENABLED
>>> >> > http://hdfgroup.org
>>> >> > HDF 4.2r3
>>> >> > HDF5 1.8.4
>>> >> > o GeoTIFF and KML output ENABLED
>>> >> > http://www.libtiff.org
>>> >> > http://geotiff.osgeo.org
>>> >> > o Shapefile interface ENABLED
>>> >> > http://shapelib.maptools.org
>>> >> >
>>> >> > Thanks for the help!
>>> >> >
>>> >> > Nick
>>> >> > _______________________________________________
>>> >> > gradsusr mailing list
>>> >> > gradsusr at gradsusr.org
>>> >> > http://gradsusr.org/mailman/listinfo/gradsusr
>>> >>
>>> >> --
>>> >> Jennifer M. Adams
>>> >> IGES/COLA
>>> >> 4041 Powder Mill Road, Suite 302
>>> >> Calverton, MD 20705
>>> >> jma at cola.iges.org
>>> >>
>>> >>
>>> >>
>>> >>
>>> >
>>> > _______________________________________________
>>> > gradsusr mailing list
>>> > gradsusr at gradsusr.org
>>> > http://gradsusr.org/mailman/listinfo/gradsusr
>>> >
>>> >
>>>
>>>
>>>
>>> --
>>> *************************************************
>>> Dr. Ya-Qiang Wang
>>> Centre for Atmosphere Watch and Services (CAWAS), CMA
>>> Chinese Academy of Meteorological Sciences (CAMS)
>>> 46, Zhong-Guan-Cun South Avenue
>>> Beijing, 100081
>>> China
>>>
>>> yaqiang.wang at gmail.com
>>> **************************************************
>>>
>>> _______________________________________________
>>> gradsusr mailing list
>>> gradsusr at gradsusr.org
>>> http://gradsusr.org/mailman/listinfo/gradsusr
>>>
>>
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>>
>
>
>
> --
> *************************************************
> Dr. Ya-Qiang Wang
> Centre for Atmosphere Watch and Services (CAWAS), CMA
> Chinese Academy of Meteorological Sciences (CAMS)
> 46, Zhong-Guan-Cun South Avenue
> Beijing, 100081
> China
>
> yaqiang.wang at gmail.com
> **************************************************
>
--
*************************************************
Dr. Ya-Qiang Wang
Centre for Atmosphere Watch and Services (CAWAS), CMA
Chinese Academy of Meteorological Sciences (CAMS)
46, Zhong-Guan-Cun South Avenue
Beijing, 100081
China
yaqiang.wang at gmail.com
**************************************************
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