I have been trying hard how to go about mapping India more efficiently as the data was very distributed and rarely available in a compiled format. Now I have found a way of mapping major roads, places. These two things rarely change in the landscape. So even very old sources of data can come very helpful at times. I got my hands on the old 1940s maps of US army corps which are available online at http://www.lib.utexas.edu/maps/ams/india and that proved to be a boon for mapping roads for me.
Here are the steps I followed:
1.Use JOSM for mapping - include the WMS and PicLayer Plug-ins.
2.Download the map area of the region to map from http://www.lib.utexas.edu/maps/ams/india
3.Open JOSM and get the OSM data for the region to map.
4.Load the JPG image of US Army Corps map using the PicLayer
5.Adjust the width and alignment of the map. (The best technique is to place two points at corner LAT-LONGs and align the map on those two points)
6.Use the WMS plug-in to load the Landsat imagery (I chose Black&White imagery for clear lines).
7.By switching between the piclayer and lansat layer we can deduce the correct path of roads and places on the map.
The work is tedious sometimes when the imagery is poor, but its worth the effort and some good roads can be drawn by this way. There may be some issues about accuracy for some people, its there, but I suggest this method for remote areas which no one is going to map for at least a year from now. Moreover the major roads don’t change and that pretty good method.