Can I convert a Winkel Triple projection raster image to Mercator?

[Alfredo Saavedra]

Hi Guys, I am a noob in cartography, although I am finding it very fascinating. I've learned a lot in the last week.

Here is my problem, I got lots of raster format maps (jpg files) that have the Winkel Triple projection that need to be transformed to Mercator projection. Is it possible? What software (freeware) would you recommend?

Thank you a lot.

~Alfredo

[waldronate]

FlexProjector ( http://www.flexprojector.com/ ) will likely do what you want.

[Hai-Etlik]

Hi Guys, I am a noob in cartography, although I am finding it very fascinating. I've learned a lot in the last week.

Here is my problem, I got lots of raster format maps (jpg files) that have the Winkel Triple projection that need to be transformed to Mercator projection. Is it possible? What software (freeware) would you recommend?

Thank you a lot.

~Alfredo

Winkel Tripel doesn't have a closed form inverse. Which, in non-math speak means there isn't an easy way to get from Winkel Tripel to latitude and longitude, you have to sort of guess, and then revise the guess repeatedly until you get something close enough (and you have to do that for every point). Most projection software only provides inverse projections where a closed form solution exists so you probably won't find much, and if you do, it should be fairly slow and/or imprecise.

[Gidde]

In light of what Hai-Etlik said, I can't guarantee the quality, but Flexify 2 by Flaming Pear software (it's a Photoshop plugin) will take a Winkel Triple input. It's worth mentioning too, that I've successfully used flexify in gimp with gimp's plugin for PS filter support.