[gdal-dev] What should I expect?

[Even Rouault]

Le vendredi 10 août 2012 22:28:34, Jorge Arevalo a écrit :
> Hi,
> 
> Many thanks for your response, Martin. So, it doesn't need to be a
> mistake. Just a flipped image.
> 
> The doubt raised because, for example, gdalbuildvrt doesn't accept ns
> positive resolution values. Looking at this old ticket
> http://trac.osgeo.org/gdal/ticket/3432, seems that that kind of raster
> data can't be mosaiced. You get an error. I don't understand why.
> 
> I know cartesian coordinate system sets the origin in the bottom left
> corner, while images set the origin in the top left  corner. So, the
> ns resolution of a georeferenced image is negative. Otherwise, you get
> a south up image. But... if all the images you want to mosaic have
> this "problem" (positive ns resolution), why I can't mosaic them using
> gdalbuiltvrt?

Jorge,

You could certainly remove this limitation of gdalbuildvrt. I put it because 
I'm lazy and don't usually deal with south-up images (and because images with 
postive ns resolution are in 99% of the cases in fact ungeoreferenced images, 
which you don't want to mosaic). I suspect that just removing the test might 
make things work. I let you experiment with that.