[gradsusr] set shp -poly

Thu Jan 5 11:07:14 EST 2012

Jennifer...

     I gave it a try, had my reservations with all the lines ...
what I meant by the comment on the dbf was I have never seen
the listing of 'min_value' and 'max_value' , that was a first for me..

now to write up my scripting for wgrib2 to pull out a list of locations
to plot on the map...

anybody interested ...

GRIB2 -->
GRaDS shapefile conversion -->
OGR2OGR postgresql GIS database -->
custom php scripting for maps

all total it takes less then 45 seconds for my system to complete
the above ..

-Jeff Lake
MichiganWxSystem.com
WeatherMichigan.net
TheWeatherCenter.net
GRLevelXStuff.com

On 1/4/2012 6:20 PM, Jennifer Adams wrote:
> Jeff,
>
> On Jan 4, 2012, at 12:19 PM, Jeff Lake wrote:
>
>> This is exactly the problem ...
>> the dbf is also in a format I nor GDAL has ever seen before,
> In GrADS, you can issue the 'q dbf' command and it will spew the 
> contents of the dbf file. The utility 'dbfdump', which comes with the 
> shapefile library, also has no trouble reading the dbf file. There is 
> very little structure to the dbf file, it's just a list of attributes 
> and the values that go with them for each element in the file.
>
>> could be this temp, but yet it could be this???
> I'm sorry, but I don't understand this statement.
>
>>
>> this is the GRIB file I'm using
>> http://weather.noaa.gov/pub/SL.us008001/ST.opnl/DF.gr2/DC.ndgd/GT.rtma/AR.conus/RT.01/ds.temp.bin
>>
>> the RT.01 determines the cycle hour
>>
>> GrADS version 2.0.1,
>> CentOS 5.7 64bit
>>
>>
>> and the script snippet
>>
>> 'clear shp'
>> 'set lat 20 55'
>> 'set lon -150 -45'
>> 'set gxout shp'
>> 'set mproj latlon'
>> 'set ccols 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22'
>> 'set clevs -40 -35 -30 -25 -20 -15 -10 -5 0 5 10 15 20 25 30 35 40 45 50
>> 55 60 65 70 75 80 85 90 95 100 105 110 115 120 125 130 135'
>> 'set shp -poly rtma_temp'
>> 'd (TMP2m-273.16)*9/5+32'
>> 'quit'
>
> I grabbed the file, used g2ctl, and drew a grfill plot with GrADS, 
> overlaying a shapefile with the state boundaries (instead of the 
> default map plotted by GrADS). Here is the result:
> Next I used 'gxout shp' and created a shapfile based on this data. 
> Then I import the shapefile I created into Qgis and draw it using no 
> outline and coloring in the polygons according to the classification 
> field MIN_VALUE and then overlay the same shapefile (statesp020) and 
> get this:
>
>
> There is no re-projecting going on, the plots are the same, other than 
> the color scheme -- it's a pain to define colors in Qgis, so I used 
> this blue/green palette. As far as I can tell, there is nothing wrong 
> with the shapefile created by GrADS.
>>
>>
>> I would let GrADS do my mapping, but I'm some what of a stickler about
>> my maps looking the same
>> I cannot for the life of me get GrADS to match my projection
>> http://contours.michiganwxsystem.com/forecasts/gfs/gfsmos_d1_maxt.png
>> I got GEMPAK to match (and they say that is harder), but not GrADS :(
>
> As for the projection in your michiganwxsystem plot, it doesn't appear 
> to be drawn with GrADS, but it looks like a polar stereographic 
> projection. In GrADS, use 'set mproj nps' and then display your 
> temperature plot and it will look like this:
>
>
>
> This looks like the projection in the image on your website. As for 
> getting Qgis to draw in a polar stereographic projection ... I have no 
> idea how to do this. Perhaps this is another user in the forum who 
> will know.
> --Jennifer
>
>>
>> -Jeff Lake
>> MichiganWxSystem.com <http://MichiganWxSystem.com>
>> WeatherMichigan.net
>> TheWeatherCenter.net
>> GRLevelXStuff.com
>>
>>
>> On 1/3/2012 7:43 PM, Yaqiang Wang wrote:
>>> It seems GrADS does not form real 'polygon' from contour lines by
>>> topology analysis. This is the source of the problem.
>>>
>>> On Wed, Jan 4, 2012 at 7:17 AM, Jennifer Adams<jma at cola.iges.org> 
>>>  wrote:
>>>> Jeff,
>>>> The shapfile interface in GrADS creates a shapefile that contains 
>>>> polygons
>>>> that fill out the areas outlined by the shaded contours. Because of the
>>>> rules in the shapefile spec regarding polygon geometry, the area 
>>>> inside a
>>>> shaded contour is split up into many pieces so that individual 
>>>> polygons do
>>>> not overlap and do not contain holes (no donuts). That is why you 
>>>> are seeing
>>>> all the vertical lines. If you color in the polygons and use the 
>>>> same color
>>>> to draw the outline, you won't see the vertical lines and the plot 
>>>> will look
>>>> more normal (like the shaded contour plot in GrADS).
>>>>
>>>> Also, before you create the shapefile, you must be in the latlon 
>>>> projection
>>>> (set mproj latlon). No other projection will work. It should be 
>>>> possible to
>>>> use your GIS tool to re-project the data in the shapefile using the 
>>>> metadata
>>>> in the file provided by GrADS. From the attachement you sent, it's 
>>>> difficult
>>>> to tell what the problem is -- better to draw a plot of a variable 
>>>> such a
>>>> land mask that would clearly show whether the boundaries in the 
>>>> data are
>>>> lining up with the political boundaries (and color them in and use 
>>>> matching
>>>> outline color). If there is an issue in the way Qgis is 
>>>> re-projecting the
>>>> shapefile, then that may or may not be a GrADS problem.
>>>>
>>>> The polygons 'connect to the outside' because they are filling in the
>>>> lat/lon block defined by your dimension environment. You can't mask 
>>>> your
>>>> shapefile according to political boundaries, but you can choose to 
>>>> not draw
>>>> a certain contour level by using -1 instead of a color number in 
>>>> the 'set
>>>> ccols' command.
>>>>
>>>> I can't help you any further without more specific information 
>>>> about what
>>>> version of GrADS you're using, what the descriptor file looks like 
>>>> for your
>>>> data, the source of your data file (so I can grab a sample), what your
>>>> commands were to generate the shapefile, and what you did inside 
>>>> Qgis to
>>>> create the display in your attachment.
>>>> --Jennifer
>>>>
>>>>
>>>>
>>>>
>>>> On Jan 3, 2012, at 4:22 PM, Jeff Lake wrote:
>>>>
>>>> I believe there is a minor, okay major, flaw in the conversion to 
>>>> shape file
>>>> here is the shape file I get when converting the RTMA GRIB over (see
>>>> attachment)
>>>> the resulting polygons all 'connect' to the outside
>>>> this is a cint set from -30 to 140 by 5 degree's
>>>> this is a better result then another piece of software, but still not
>>>> correct..
>>>>
>>>> anybody got suggestions ??
>>>>
>>>> --
>>>> -Jeff Lake
>>>> MichiganWxSystem.com
>>>> WeatherMichigan.net
>>>> TheWeatherCenter.net
>>>> GRLevelXStuff.com
>>>>
>>>> <rtma.jpg>_______________________________________________
>>>> 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
>>>>
>>>>
>>>>
>>>>
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>>>>
>>>
>>>
>> _______________________________________________
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>
> --
> Jennifer M. Adams
> IGES/COLA
> 4041 Powder Mill Road, Suite 302
> Calverton, MD 20705
> jma at cola.iges.org <mailto:jma at cola.iges.org>
>
>
>
>
>
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