During the cold war the Soviet military secretly mapped the entire world using detailed topographic maps:
Although focus was on US and Europe, much of Asia was also mapped in 1:100K and 1:200K scale maps. The topographic accuracy of these manually cartographed maps is impressive when comparing to modern day satellite generated digital elevation models.
For the outdoor community, the Soviet topographic maps of the Western Himalayas include useful terrain features including many high passes and trails across high ranges. Let’s take a closer look a one sample 1:100K Soviet army map and compare to the Survey and Olizane maps. Download this Soviet map of the same region we looked at earlier and geo-reference the same in QGIS:
https://drive.google.com/file/d/1DTGTirJbPzsO3y18ppLwImciOXj1eDSV/view?usp=sharing
Use the standard EPSG:4326 – WGS 84 CRS (Coordinate Reference System) to map the 4 corners of the map using latitude and longitude mentioned on the map. See Image 1+2 below.
Verification
Let’s verify whether we geo-referenced the Soviet map accurately by cross-referencing with other standard maps. Overlay the Soviet map with 50% transparency over an “OpenTopoMap” base layer and compare the topography (valleys, ridgelines). See Image 1 below.
Similarly overlay the Survey map with 50% transparency over the Soviet map and compare the terrain features of both. You will see a slight mismatch of rivers between both maps. This might be related to inaccurate cartography of the Soviet maps or possibly inaccurate geo-referencing (not entire sure on the CRS used on the Soviet maps). See Image 2 below.
In the third image below we overlay the Soviet map over the Olizane map and can see a matching topography. The Soviet map has finer contours compared to the Olizane map (100m contours),
Comparison
Below image 1 shows a comparison of the regions covered by the three maps we geo-referenced so far:
1:50K Survey map covers 15’x15′ or roughly 28x28km
1:150K Olizane map covers 1.3″x08″ or 144x89km (complete map, we only geo-refed a part in this chapter)
1:100 Soviet map covers covers 0.5″x20′ or 55x37km
See Image 1 below.
Second image below compared the detail shown on the three maps covered so far. This is roughly in relation to the scale of each map: Survey 1:50K (finest detailed), Soviet 1:100K (medium detail) and Olizane 1:150K (less detailed terrain features).
Assignment
It’s time for hands-on now to acknowledge your understanding of the concepts taught in this module. Download the Soviet map from the link above, geo-reference in QGIS and compare to the Survey, Olizane and Open Topo maps.
