<font face="courier new,monospace">I have also had an issue with the geotransform being of by a factor of 1000, but it was a units issue. GDAL kind of assumes CF=1.x convention, as netcdf is very broad in its specification. Could you attach a small sample dataset to a ticket so I can take a look? Thanks.<br>
<br>kss<br clear="all"></font><br># ============================<br>Kyle Shannon<br>Physical Science Technician<br>RMRS Fire Sciences Lab<br>Fire, Fuels & Smoke - RWU 4405<br>5775 Highway 10 W.<br>Missoula, MT 59808<br>
(406)829-6954<br><a href="mailto:kshannon@fs.fed.us">kshannon@fs.fed.us</a><br># ============================<br>
<br><br><div class="gmail_quote">On Thu, May 20, 2010 at 8:37 PM, Ole Nielsen <span dir="ltr"><<a href="mailto:ole.nielsen@aifdr.org">ole.nielsen@aifdr.org</a>></span> wrote:<br><blockquote class="gmail_quote" style="margin: 0pt 0pt 0pt 0.8ex; border-left: 1px solid rgb(204, 204, 204); padding-left: 1ex;">
<br>
Dear GDAL developers<br>
<br>
I have been using GDAL for a while with great success and really appreciate<br>
the toolkit.<br>
As of recently, I now have the need to read NetCDF files and convert them<br>
into AAIGRIDs. However, the cellsize is wrong and I don't think xllcorner<br>
and yllcorner are correct either.<br>
<br>
I have searched this forum and I think this may be related to the thread<br>
named "[gdal-dev] netcdf to geotiff and aaigrid" from 2008. However, I<br>
didn't find a resolution in that thread - hence this posting.<br>
<br>
The content of the NetCDF file is obtained by running ncdump <a href="http://merapi.res.nc" target="_blank">merapi.res.nc</a>:<br>
<br>
netcdf merapi.res {<br>
dimensions:<br>
x = 59 ;<br>
y = 64 ;<br>
alt = 6 ;<br>
time = UNLIMITED ; // (4 currently)<br>
variables:<br>
float x(x) ;<br>
x:units = "m" ;<br>
x:description = "UTM. West-East distance" ;<br>
float y(y) ;<br>
y:units = "m" ;<br>
y:description = "UTM. South-North distance" ;<br>
.... (many lines removed here)<br>
data:<br>
<br>
x = 412432.3, 413449.5, 414466.8, 415484, 416501.2, 417518.5, 418535.7,<br>
419553, 420570.2, 421587.4, 422604.7, 423621.9, 424639.1, 425656.4,<br>
426673.6, 427690.8, 428708.1, 429725.3, 430742.6, 431759.8, 432777,<br>
433794.2, 434811.5, 435828.7, 436846, 437863.2, 438880.4, 439897.7,<br>
440914.9, 441932.2, 442949.4, 443966.6, 444983.8, 446001.1, 447018.3,<br>
448035.6, 449052.8, 450070, 451087.3, 452104.5, 453121.8, 454139,<br>
455156.2, 456173.5, 457190.7, 458207.9, 459225.2, 460242.4, 461259.6,<br>
462276.9, 463294.1, 464311.3, 465328.6, 466345.8, 467363.1, 468380.3,<br>
469397.5, 470414.8, 471432 ;<br>
<br>
y = 9106709, 9107724, 9108740, 9109756, 9110772, 9111788, 9112804, 9113820,<br>
9114836, 9115851, 9116867, 9117883, 9118899, 9119915, 9120931, 9121947,<br>
9122962, 9123978, 9124994, 9126010, 9127026, 9128042, 9129058, 9130073,<br>
9131089, 9132105, 9133121, 9134137, 9135153, 9136169, 9137185, 9138200,<br>
9139216, 9140232, 9141248, 9142264, 9143280, 9144296, 9145311, 9146327,<br>
9147343, 9148359, 9149375, 9150391, 9151407, 9152422, 9153438, 9154454,<br>
9155470, 9156486, 9157502, 9158518, 9159534, 9160549, 9161565, 9162581,<br>
9163597, 9164613, 9165629, 9166645, 9167660, 9168676, 9169692, 9170708 ;<br>
<br>
...... (lines removed)<br>
<br>
TOPOGRAPHY =<br>
0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 51.99445,<br>
124.9918, 103.0026, 170.9917, 191.9973, 183.0012, 214.9956, 215,<br>
204.0016, 246.9934, 231.0025, 221.0016, 226.999, 224.0005, 249.9954,<br>
211.0071, 232.9959, 242.9981, 224.0038, 231.9984, 222.0021, 240.9959,<br>
271.9932, 265.0016, 284.9954, 286.9995, 289.9993, 293.999, 311.9955,<br>
274.0097, 294.9946, 282.0034, 302.9944, 317.9959, 311.002, 314.9989,<br>
330.9954, 338.9977,<br>
0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 105.9893, 183.9907,<br>
183.9983, 189.9981, 199.9982, 200.999, 215.9977, 224.9986, 217.0007,<br>
264.993, 260.0003, 273.9973, 246.0043, 249.9992, 291.9925, 299.998,<br>
300.9991, 277.004, 256.0034, 272.9964, 252.004, 246.001, 243.0005,<br>
256.9968, 242.0032, 268.9941, 253.0037, 249.0013, 272.9945, 271.0006,<br>
277.9984, 263.0042, 266.9991, 277.9973, 312.9904, 322.9971, 295.0079,<br>
295.0002, 273.0067, 336.9814, 334.0009,<br>
0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 96.98979, 189.9899,<br>
180.001, 205.9969, 205.9997, 213.9988, 236.9966, 240.999, 255.9975,<br>
...... etc etc<br>
<br>
========================<br>
<br>
The command I use to extract this topography variable is<br>
gdal_translate -of AAIGrid NETCDF:"<a href="http://merapi.res.nc" target="_blank">merapi.res.nc</a>":TOPOGRAPHY<br>
merapi.topography.asc<br>
<br>
and the header of the resulting file is<br>
ncols 59<br>
nrows 64<br>
xllcorner 0.000000000000<br>
yllcorner -64.000000000000<br>
cellsize 1.000000000000<br>
NODATA_value 9.9692099683868690468e+36<br>
0 0 0 0 0 0 0 0 0 0<br>
0 0 0 0 0 0 0 0 0 0 0<br>
51.99444<br>
9615478515625 124.9918365478515625 103.00257110595703125 170.99169921875<br>
191.9973297119140625 183.001190185546875 214.99560546875 215<br>
204.001617431640625<br>
246.993438720703125 231.0025177001953125 ........<br>
<br>
---------------------------------------------------------<br>
<br>
I do not understand why the cellsize is 1.000000 when it should be in the<br>
order of 1000.<br>
Also, I do not understand why xllcorner and yllcorner aren't obtained as<br>
e.g. the minimum values of the x and y vectors.<br>
<br>
The version of gdal-bin is 1.5.2-3ubuntu1 and my platform is Ubuntu 9.04 (64<br>
bit).<br>
<br>
By the way, trying to contour directly from the NetCDF puts all the contours at the south pole. I suspect this is another manifestation of the origins being ignored.<br>
<br>
Can anyone help please?<br>
<br>
Cheers and thanks<br>
Ole Nielsen<br>
<font color="#888888"><br>
<br>
--<br>
View this message in context: <a href="http://osgeo-org.1803224.n2.nabble.com/gdal-translate-netcdf-to-aaigrid-wrong-cellsize-xllcorner-and-yllcorner-tp5073995p5073995.html" target="_blank">http://osgeo-org.1803224.n2.nabble.com/gdal-translate-netcdf-to-aaigrid-wrong-cellsize-xllcorner-and-yllcorner-tp5073995p5073995.html</a><br>
Sent from the GDAL - Dev mailing list archive at Nabble.com.<br>
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</font></blockquote></div><br>