Finally - a free reprojection utility for background im...

[Guest hefy_jefy]

OK Dan,Thanks! I'll give it a try...I agree about all the hoops you need to go through, it wasn't until I started to try making large E-W maps that I noticed the need for it, but now I know about it I have noticed that magically all the roads now run in the bottoms of the valleys!Geoff

[Guest papa.looser]

Hi there,this tutorial has been working fine for me so far, however, now I'm having trouble interpreting the formula right: N(subset) = N(original) - (Yres * Nrow)W(subset) = W(original) + (Xres * Wcolumn)S(subset) = N(original) - (Yres * Srow)E(subset) = W(original) + (Xres * Ecolumn)In Photohshop I cut out a rectangle of 5000x2000px size,with the left upper edge at x: 2815 and y:1485This is what my .tfw says:28.5000000000000000.00.0-28.500000000000000292353.000000000005370854.0000000000This is my (definitly wrong) interpretition of the formula:N(subset) = 5370854 - (28.5 * 1485) W(subset) = 292353 + (28.5 * 2815) S(subset) = 5370854 - (28.5 * 3485) E(subset) = 292353 + (28.5 * 7815)If somebody could please lead me to the right way, to get reasonable coordinates.

[Holger 0]

Howdy,your tfw file indicates that your source data are still in the original UTM projection, not the required lat/long. What steps did you take prior to ending up with the tfw file?Cheers, Holger

[Guest hefy_jefy]

I found the problem with ERDAS viewfinder.In the dialog box Northings increase upwards.Not downwards... Duh! (It still should crash though)Good thing; I am not a programmer so the GDAL option was not a good one.The confusion comes from my oldfashioned need to work from the bottom left - not the top left (you go in the house before going upstairs)Its working fine now...Geoff

[Guest papa.looser]

Hi Holger,thanks for your reply.This is what I did so far:1. downloaded band 1, 2, 3.2. opened each in ERDAS ViewFinder3. saved each as TIFF (maybe here is the problem, as a save-as may not mean by default a reprojection???)4. merged those TIFFs in Photoshop.Most likely I did a mistake doing step 3, the reprojection.Could you plead explain how a reprojection is done?Is this eventl. in the save-as dialog checking 'change output projection'?Looks like you already led me there!If so, another question arises, what is there the difference between projection for Germany and Germany_85_Potsdam?