I live in Dhaka, the capital of Bangladesh. It is a densely populated area to live in. Remote Mapping in Dhaka is also difficult because the imagery quality is not that great and the buildings are so dense that it is hard to separate from one another. However, I noticed that the imagery in Dhaka has two layers. Upto zoom level 18, there is one imagery that is quite clear but small to draw from. From zoom level 19, another imagery that is quite unclear, dense and sometimes covered in cloud. So I figured a way out to use the first imagery to draw from. I made a video about it. Here is the link:

https://www.youtube.com/watch?v=gRTnKmbbaTo

So far, this is helping a lot. I am not sure if this trick can be used elsewhere but this is worth a try.