On Tue, 2009-02-17 at 02:01 +0100, Uwe Stöhr wrote: > Nikos Alexandris schrieb: > > > I am interested in this statement... > > Could you please extent a bit or give some pointers? > > This is now a bit off-topic.
Once and a while it doesn't hurt :-) > I maintain at work a scanning electron microscope (SEM). Due to technical > reasons the distance > between the pixels in x-direction is different from the y-direction. So you > usually take SEM images > with 512x512 pixels, but get a rectangular, non-quadratic image. This is, more or less, also the case with images referenced in a geographic coordinate system (think degrees, minutes, seconds). X and Y are in reality different since latitude varies greatly when you measure it near the equator against higher latitudes. The maps (images) look "distorted" but they are still, on-display, rectangulars. Anyhow, the scales (geo-maps vs. SEM's) have nothing to do :-) I wonder if GRASS-GIS, which is a power-full raster engine, could be of any use for SEM images? Why not referencing to a micro-scale reference system images and play around? :D You can also play around with voxels and 3D-stuff. For the fun of the game I would like to try it out some day. I might even post to folks over in GRASS-user mailing list about this (foolish perhaps) idea. > The image format is TIFF and the pixel distance is specified in the TIFF > header. I understand here "distance" as "resolution". Something like an image in which the x-dimension of a pixel is 1 metre and the y-dimension of the pixel is set to be 1.5 metre. > Unfortunately the > only program that checks for the pixel distance is Windows' built in image > viewer. In e.g. Adobe > Acrobat you have to specify the pixel distance manually to get a > non-distorted image. So you mean you have to set manually the resolution of x-y if I get it right. Just for the records: under Linux you have for example imagemagick (a "great", in number and in abilities, collection of image manipulation tools). I am pretty sure you could do neat stuff with your images. > > regards Uwe Kind regards and thank you for your explanation. Nikos
