IM

Trying to select orange or brownorange horizontals:

horizontals.jpg

paths.jpg

highway-mask.gif

convert highway_mask.gif -blur 0x4.0 -threshold 25%% highway_threshold_40.png
highway_threshold_40

convert highway_threshold_40.png -morphology Thinning:-1 Skeleton  highway_thinned.gif

highway_thinned

Better quality and a little bit faster (+1/7):
convert highway_threshold_40.png -morphology Thinning:-1 Skeleton  highway_thinned.gif

small blur

highway_blur_2

compare -metric RMSE -subimage-search highway_mask.png small_img_board_1.png result.png     

subimage:

sub

 Or resize image

subimage:

the result after levels:

and back resized:

which

Water surface search on the same map:

subimage:

The result is weird:

Blend:

Water surface 2:

next try