Etienne,<br><br>Rasters of type Byte cannot hold values below 0. So, the nodata value of -1 is not practical. It's better to choose 0 or 255 depending on your data or choose a different data type.<br><br>Your problem arises because the two geometries in the shapefile overlap in some places and leave some gaps between them in other places.<br>
Consider selecting only one feature using the -where option in gdal_rasterize. You can also use the -at option but it may not work at all resolutions.<br><br><div class="gmail_quote">On Fri, Aug 5, 2011 at 7:40 AM, Etienne <span dir="ltr"><<a href="mailto:etiennesky@yahoo.com">etiennesky@yahoo.com</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;">Hi all,<br>
<br>
I am trying to create a raster file with categorical data (land vegetation/cover positive indices) from a shapefile containing 1 layer of polygons. <br>
<br>
I use the following command: <br>
gdal_rasterize -tr 0.0005 0.0005 -a_nodata -1 -of GTiff -a_srs EPSG:4618 -a "CLASSE_ID" -ot Byte -init -1 -l region1 region1.shp region1-3.tif<br>
<br>
This creates a map which looks good, but there are some holes in the data, (individual pixels with a value of 0) at the intersection of 2 polygons. It looks like the<br>
intersections pass through the exact center of these pixels. These pixels are not set to missing(-1). Depending on the output resolution, different pixels get set to a value of 0.<br>
<br>
Has anyone ran into this problem? Any idea how to fix this? <br>
Those interested will find 2 small shapefiles here: <a href="http://db.tt/3X4hI45" target="_blank">http://db.tt/3X4hI45</a> and <a href="http://db.tt/phqnGci" target="_blank">http://db.tt/phqnGci</a><br>
<br>
<br>
I tried using gdal_grid, but it doesn't seem to support a shapefile with POLYGONs.<br>
<br>
many thanks!<br>
Etienne<br>
<br>
_______________________________________________<br>
gdal-dev mailing list<br>
<a href="mailto:gdal-dev@lists.osgeo.org">gdal-dev@lists.osgeo.org</a><br>
<a href="http://lists.osgeo.org/mailman/listinfo/gdal-dev" target="_blank">http://lists.osgeo.org/mailman/listinfo/gdal-dev</a><br>
</blockquote></div><br><br clear="all"><br>-- <br>Best regards,<br>Chaitanya kumar CH.<br><br>+91-9494447584<br>17.2416N 80.1426E<br>