3

Further to Where do I find the legend for netCDF files in QGIS?, I have .nc and .asc files of crop area and production for maize, rice and wheat. It says here, about QGIS importing .asc files:

QGIS has native support for this format. ESRI grid (.asc) files can be directly opened in QGIS by selecting Layers >>> Add Raster Layer. The .asc file can also be dragged and dropped into the QGIS session, rather than using the Add Raster Layer option.

But when I do either, I get this error:

.asc is not a supported raster data source.

which has been reported at Is .asc supported raster data source for QGIS?

I am using version 2.0.1-Dufour.

  • it is a problem of GDAL. What is your OS (Windows, Linux, Mac) ? (GDAL raster format) – gene Dec 7 '14 at 19:18
  • Windows 7, 8Gb RAM. But I just noticed something weird about these files. They're about 100 MB and they contain (looked with Textpad) nothing but endless rows of -9999.000, -9999.000, -9999.000 -9999.000 -9999.000. Not sure what that means (oceans?). Got them from here: geog.mcgill.ca/landuse/pub/Data/175crops2000/ArcASCII-Zip – plugincontainer Dec 7 '14 at 19:30
  • Look at the header NODATA_value -9999.000: there are empty asc files. The format is described in ESRI grid – gene Dec 7 '14 at 19:47
6

I just downloaded one of the files in the repository that you linked to (brazil_yield.asc) and tried to import the file into another GIS program. I also ran into an import error. I finally tracked the error down to an attempt to convert a blank cell to a numerical type. In other words, there are blanks in the file because they have been improperly formatted. Rewriting the import tool to ignore blank cells resulted in a successful import. There are several places in the file that have two spaces in a row. See the figure below.

enter image description here

For a proper space delimited file, there can only be one space between each number.

  • Well done, it works – gene Dec 7 '14 at 21:14
  • Yes, scrolling (very slowly) with Textpad I noticed those odd spaces. – plugincontainer Dec 7 '14 at 22:04
  • 2
    @plugincontainer You can probably just do a find and replace in textpad to replace the multiple spaces to a single space and it'll import successfully. Good luck. – WhiteboxDev Dec 7 '14 at 22:16
  • Hey @WhiteboxDev - I tried global search-and-replace with Textpad, Word and OpenOfficeWriter and they can't handle that many replaces ("program is not responding"). Started doing it in blocks in Word and it's neverending - thousands of spaces to fix. Do you know how I can tell QGIS to do what you did, i.e. "ignore blank cells"? – plugincontainer Dec 8 '14 at 6:27
  • @gene ... finally got rid of all double spaces. But QGIS won't accept it. What is the GDAL issue? – plugincontainer Dec 8 '14 at 10:51
1

QGIS will not import ESRI ASCII format if the header contains leading whitespace of any kind. Remove leading whitespace and QGIS will load the file correctly.

1

I had similar difficulties to import an ASCII file into QGIS. I opened it with a texteditor to have a look on it. There was a header with information about the author, coordinate system, etc. I removed this part, so that the file had the following structure given from ESRI:

NCOLS 654
NROWS 866
XLLCORNER 3281000
YLLCORNER 5238000
CELLSIZE 1000
NODATA_VALUE -999
-999  -999  -999  -999  -999  -999 ...
...

Finally, I was able to open the file in QGIS with 'Add Raster Layer'.

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