How to fill coastline polygon

Does anyone knows how to fill a coastline polygon? I'm trying to make SST contourf maps for the Mexican Pacific, but I don't know how to superimpose the filled "ground", so it covers the contours of the gridded area, where I don't have any oceanographic stations. I'll apreciate if anyone could tell me how to do it. Thank you.

Answer 1

[Rob Comer]

Mapping Toolbox has two functions for plotting filled polygons: geoshow and mapshow, as well as a low-resolution coastline data set, coast.mat. Use geoshow when working with a projected map axes. For example, if you load coast like this: coast = load('coast.mat'), then you could call geoshow like this: geoshow(coast.lat, coast.long, 'DisplayType','polygon','FaceColor','green').

You mentioned contourf (rather than contourfm), so you're probably in a ordinary axes. In that case, use mapshow instead, and swap the order of the first two inputs. For example: mapshow(coast.long, coast.lat, 'DisplayType','polygon','FaceColor','green').

As Mark mentioned in his answer, one way to work in higher resolution is to import GSHHS coastline data via the gshhs function.

Answer 2

[Mark Brandon]

Millo,

if you have the mapping toolbox then you can use tools such as gshhs

http://www.mathworks.co.uk/help/toolbox/map/ref/gshhs.html

But if not then you can use the tools in m_map which is an excellent package

http://www.eos.ubc.ca/~rich/map.html

There are many tools (and examples) in that package which you can use.

Else you could get the coastline from the NOAA Coaslie extracter

http://www.ngdc.noaa.gov/mgg/coast/ and make your own patch.

Or you can use the tools the WHOI Sea-Mat Page

http://woodshole.er.usgs.gov/operations/sea-mat/

And look at the code under the map_stuff link which sends you here

http://woodshole.er.usgs.gov/operations/sea-mat/mapstuff-html

Lots of choices for you to try.

Good luck, Mark

[Millo Marin]

I have my own coastline from the coastline extractor (NOAA)... how do I make the patch? Sorry, I'm new at MATLAB. Thanks a lot.

[xiao gh]

it's interesting

Answer 3

[Millo Marin]

I have the data for the coastline, I extracted it from the NOAA coastline extractor.. when I plot the contourf interpolated plot, I use the hold on comand, then plot the coastline over the contourf plot. I do have the mapping toolbox, I tried with the mapshow option, but it draws the coastline as a polygon, and I miss some of the resolution in the coastline (like bays and capes). I don't know if I can upload an image of the plot, so yo guys can see it and better understand my problem.. Sorry, I'm really new at Matlab. Thanks a lot!

Answer 4

[Mark Brandon]

It sounds like you are getting this sort of thing

http://woodshole.er.usgs.gov/operations/sea-mat/images/map_stuff.gif

If you have followed that path Millo then you should follow the m_map link I posted above - and the sea-mat page.

You could try "patch" instead of contourf.

Personally I would recommend that you you look at the (free) m_map toolbox function "m_gshhs_h" described in example 11 on this page

http://www.eos.ubc.ca/~rich/private/mapug.html

for example here are the different resolutions in the GSHHS

http://www.eos.ubc.ca/~rich/map.html#9._Zoom_in_on_Prince_Edward_Island_to_co

There will be a bit of downloading of the gshhs data but I think it is worth it.

good luck. Mark

Answer 5

[Millo Marin]

Sorry guys, I have been really busy latelly.. yes, that is exactly what I'm getting. I already have the m_map toolbox, I just haven't had the time to get into it... thanks a lot!

Answer 6

[Mark Brandon]

You could "accept" an answer Millo then to close the question ;-)

cheers. Mark

Answer 7

[Chad Greene]

Two more options:

1. If you're trying to mask grid cells that are in land, use landmask.

2. If you want to place a patch object on top of gridded data, use borders.