![]() In effect, the UTM system assumes objects from different zones will never be seen together in the same map.Ĭombining objects from different UTM zones into a map that is projected using only one of those UTM zones will result in distortion in the locations and shapes of the objects that originated in a different zone map. Such plans fail to take into account that UTM is an intrinsically inflexible system. The motivating factor is often a desire to create a map centered on a region of interest that spans several UTM zones or which is centered between two zones. New users of UTM therefore will frequently attempt to “combine” different maps created in different UTM zones into one map with the expectation that the combined map will show all objects with low distortion as did the original maps. Thus in order to avoid such distortions, only a specified UTM zone should be applied for a specific area. ![]() ![]() Why this happens? Because each UTM Zone is in fact a different projection using a different system of coordinates (local easting and northing for each zone). Similar shift in 41N and 42N for 43N zone. We can clearly see that there is a shift in boundary towards north when we applied 42N and 43N zones for 41N region. Below map shows what sort of distortion/shifting can occur at what area when different UTM zones are applied to the boundary of Pakistan. Now, next question arises what if we use a UTM zone blindly? The answer is “Distortions”, there might be sever distortions/shifting in geographic features which can result “ill-mapping”. Often, beginner level question is asked: what UTM zone is best suited for Pakistan? Well, a simple answer would be: it is based on the part of country we are considering, one may check zones allocation for Pakistan. Pakistan falls under northern zones of UTM i.e. Each zone exists in a North and South part of globe. It is based on 60 pre-defined standard zones to supply parameters. One can find a lot of literature on Universal Transverse Mercator (UTM), the Transverse Mercator projection is widely used around the world and works especially well for mapping areas smaller than a few degrees longitudinally, such as a state or county.
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