Plotting help reqd.

[deba]

Hi all,

i am using Surfer for some contour plots, and i need to mask the land in the plots. can anyone provide me the .bln file for masking the land region and also kindly suggest me how to go about it. region subset required is
-30 to 30N and 40 to 100 E. an early response will be very much appreciated.

thanks and regards,
deba

[yaswant]

Hi all,

i am using Surfer for some contour plots, and i need to mask the land in the plots. can anyone provide me the .bln file for masking the land region and also kindly suggest me how to go about it. region subset required is
-30 to 30N and 40 to 100 E. an early response will be very much appreciated.

thanks and regards,
deba

Deba, Attached is a gsb file that you could use for your task. However, the resolution is bit coarse. There are several ways to construct your own boundary file.
1. Go through the Golden Software repository
2. bln files from UNESCO (http://ioc.unesco.org/oceanteacher/OceanTeacher2/07_Examples/examples.htm)
3. Bulid it from ArcGIS package.
4. Open a World map (TIF) on Surfer, geo-register it, digitise the boundary lines (Read through the help how to create a bln file; its pretty simple, you need to create closed polygons and number of nodes (length) in each polygon, and assign a flag depending on what you want to blank/mask). For example, if I want two closed rectangular polygons [10W-10E, 10S,EQ] and [10W-10E, 5N-10N], I'd create a file "example.bln" which should contain
------
5, 1, "box2" (length, flag, description)
-10,5
-10,10
10,10
10,5
-10,5
5,1, "box1"
-10,-10
-10,0
10,0
10,-10
-10,-10
-------
Good luck!
y

[deba]

Thanks Dr. Yashwant,
i shall go through it and follow the approach suggested by you.

regards,
deba