As the subject of the topic: Does it possible to export a painted shader as a map to be modified in a paintng software (photoshop, gimp, krita...)? i think that is not possible at the moment, this is more a feature request or maybe to find a workaround for it.
You can paint your maps in Photoshop and use those in TG.
You can camera project this map (through camera projection) or project it on "plan Y" (top-down projection).
You can also do these things with Painted shaders of course.
If you want to "export" a painted shader then you can best make all the surfaces black, disable shadows in rendering, and make the painted shader appear white.
Then render and then you should have your mask.
You can adjust it then in Photoshop.
But all in all this sounds very very laborous and inefficient.
Makes me wonder why you want to do this and if you really *need* to do this.
Thank you for the answer! I was asking this because working with a my scene http://www.planetside.co.uk/forums/index.php/topic,18493.0.html Terragen crash in linux under wine. I have many object instances and i notice a slow rendering of the preview, and sometimes as i said, it crash when i try to paint, this more a issue in linux than in windows. Exporting a map from the painted shader and retouching it in an external editor for me will be fine. But as you explain actually the process seems quite complicated and inefficient.
The fact is that i can't run my Nvidia card with Terragen 3.1 under wine: Normally to run with my Nvidia card i need to run it with 'optirun' command in a terminal: something like that:
optirun wine tgd.exe
but it fails. And i have to use my integrated video card... not so powerful.