[gdal-dev] Can't get gdal_rasterize to work... with anything.

[Karen Pease]

The problem exists when I output straight to a PNM as well, not just
with geotiff.

Can you give me an example gdal_grid command which actually works to
create a heightmap image that your average program can read? Because I'm
getting nowhere. :( For example, as a test:

gdal_grid -ot Byte -of PNM -l is50v_haedarpunktar_24122013 -outsize 800
500 is50v_haedarpunktar_24122013.shp y.pnm

y.pnm comes up as black. od shows that y.pnm is truly blank:

0000000 032520 034012 030060 032440 030060 031012 032465 000012
0000020 000000 000000 000000 000000 000000 000000 000000 000000
*
1415200 000000 000000 000000 000000 000000 000000 000000 000000
1415217

	- kv, Karen



On lau, 2014-12-13 at 19:09 +0000, Ari Jolma wrote:
> 13.12.2014, 18:07, Karen Pease kirjoitti:
> > Okay, so, I think this may be getting me a bit closer to a solution.
> >
> > The output image of your command still wasn't viewable to me, either in
> > gimp or gwenview. However, when I used ImageMagick to convert it to a
> > PNG or other format, for the first time I saw some detail, so I guess
> > it's a tif format that the former two can't read. I tried this approach
> > on the actual dataset I want to use - IS50V_HAEDARGOGN_24122013_ISN2004.
> > And indeed, the two stage process worked - to get height lines. But what
> > I actually want is a 3d height map image, where dark colors are low and
> > bright colors are high and so forth. So I switched from -burn 1 to the
> > -3d flag. Now it started outputting 64 bit float files, however; convert
> > couldn't handle them, nor tifftopnm. So I went back to specifying -ot
> > Byte or -ot UInt16 so I can use convert. However, the images just come
> > out all black. This is the same result I get if output directly to pnm
> > with -of PNM.
> Karen,
> 
> GeoTIFFs are usually only for GIS programs, not for general image viewers.
> 
> I downloaded the elevation data (~500 MB) and to me it looks like it is 
> elevation points and lines. To make a DEM (raster where cell values are 
> elevations) you would need to use a tool like gdal_grid with the point file.
> 
> Best,
> 
> Ari
> 
> >
> > 	- kv, Karen
> >
> >
> >
> > On lau, 2014-12-13 at 09:18 +0000, Ari Jolma wrote:
> >> Karen,
> >>
> >> For example this command on my computer
> >>
> >> gdal_rasterize -burn 1 -l is50v_mannvirki_flakar_24122013 -of GTiff -ts
> >> 1000 1000 is50v_mannvirki_flakar_24122013.shp x.tiff
> >>
> >> produces a 1000 x 1000 geotiff which is mostly zeros except ones where
> >> the polygons are.
> >>
> >> Can you tell us what command did you use?
> >>
> >> Ari
> >>
> >> ps: the website was a bit difficult to use for non-icelanders.
> >>
> >> 13.12.2014, 06:18, Karen Pease kirjoitti:
> >>> Hi all,
> >>>
> >>> I'm running Fedora 21 with a fresh built gdal-1.9.2. Try as I might, I
> >>> can't get gdal_rasterize to output anything other than purely
> >>> transparent images, purely white images, or purely black images.
> >>>
> >>> I want to use it on this dataset - "Elevation data. GDB og SHP.
> >>> ISN2004":
> >>>
> >>> http://atlas.lmi.is/LmiData/index.php?id=1079838344912
> >>>
> >>> I've spent maybe 8 hours on this, including trying all sorts of
> >>> different commandlines. After finding that I couldn't get that to work,
> >>> I found some sample tutorials that includes a shp file and some command
> >>> lines to use it with gdal_rasterize:
> >>>
> >>> http://disc.sci.gsfc.nasa.gov/dataholdings/?q=recipes/How-to-Obtain-a-Shapefile-based-Data-Subset-with-GrADS
> >>> http://www.openforis.org/OFwiki/index.php/Special:WhatLinksHere/Example_data_set
> >>>
> >>> None of these work for me either (using it exactly as they say to), so I
> >>> don't think it's my shp files that's the problem; I think it's
> >>> gdal_rasterize or something it depends on. I know the problem isn't an
> >>> image viewer problem either - I've tried multiple viewers, and I've
> >>> tried saving the files to PNM to allow for manual inspection - they all
> >>> contain only the same data value repeated over and over, no variation,
> >>> just pure one color.
> >>>
> >>> What should I do? I really need to make a heightmap out of this
> >>> landscape data for inclusion into a 3d model...
> >>>
> >>>    - kv, Karen
> >>>
> >>>
> >>>
> >>>
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