Question to pick best projection

Q&A
1

Dear All GMT Users,

I would like to ask you question to pick optimal projection for one of my plots.

My region locates around Anatolia (Turkey) and my area mostly occupies along latitude. In general, mercator or transeverse mercator work very well for my plot around this area but this time it does not look as I desire for.

There are 6 degrees differences throughout longitude direction and 11 for latitude.

Thank you in advance for your answers.

Best

2

Hi @ozbeyv,

It depends a bit on what you want to achieve. As Anatolia is roughly centered around N39° E035° the Lambert Conic Conformal projection (-Jl / -JL, more in the Cookbook) might be useful. Straight lines approximate great circles and it is pretty close to map scale between the two standard parallels. It therefore has less distortion compared to the Mercator projection.

map_turkey_JL
map_turkey_JL2503×1462 146 KB

Example code:

gmt begin map_turkey_JL
  gmt coast -R25/34/47/43+r -JL36/38.5/37/41/20c -A200 \
    -ETR+gred@60 -N1/1p,red -W0.7p,blue -Sdodgerblue \
    -Bag -B+t"Turkey - Lambert Conic Conformal Projection"
gmt end show
1 Like
3

I like to use Lambert Conformal Conic projection for areas up to 3000 km across. As @KristofKoch mentions, it has much less distortion than Mercator or a UTM projection for a large area.

1 Like
4

Have you check what type of maps the official organism of Turkey use? I think that it would be most likely your best option.

1 Like
5

Hi guys,

Thanks for your useful comments. @KristofKoch I really liked Lambert projection and I decided to go for it. Thanks for the suggestion. @EJFielding , yes it looks like less distortion than mercator. @Esteban82 actually mostly they use mercator or transverse mercator, however lambert fits better for my particular case.

Thank you for giving your time. Your remarks facilitated my job.