create a smooth surface using x,y,z data gnuplot

I have a file which contains x,y,z data. Actually, the data is:

x = latitude y = longitude z= Depth

I want to create a smooth surface but I have no idea how to do it. Could anybody give me some hints to do it?

UPDATE

So, the data looks like the next lines:

-62.323 19.242 58.7
-62.213 10.886 120.2
-62.329 10.797 71.9
-62.383 10.690 1.3
-60.121 11.567 24.5
-60.481 12.894 3
-62.118 10.944 69.1
-60.825 15.803 25.5
-61.792 16.227 148.3
-63.288 10.817 28.4
-59.092 14.344 3
-61.836 11.217 67.7
-61.346 14.799 191.2
-61.152 15.427 126.6
-60.959 16.035 55.8
-61.364 15.283 151.6
-62.071 11.222 109.5
-62.420 10.672 72.1
-60.267 14.009 13.1
-60.604 14.033 65.4
-60.623 10.307 42.4
-62.272 17.936 75
-60.464 13.908 40.9
-60.722 14.701 181.5
-62.125 10.911 47.1
-62.530 10.544 5.2
-60.170 12.752 71.5
-60.929 14.635 87.9
-62.279 10.936 74.3
-62.267 10.767 75.8
-60.708 10.440 36.2
-62.440 10.463 2.6
-62.477 10.217 3
-62.399 10.651 58.7

There are more points. The idea is to create the plane or surface along the depth (the third column).

1 Answer

Basically, you plot surfaces with the splot command. data_file contains your example data points.

gnuplot> splot 'data_file'

As you want a smooth surface, you have to specify that you want gnuplot to interpolate the data. Here is an example, see for some others.

gnuplot> set hidden3d
gnuplot> set dgrid3d 50,50 qnorm 2
gnuplot> splot 'data_file' with lines

There are a lot of parameters you can adjust, e.g. what interpolation function is used. As it is very hard to cover all here in a general answer, I want to recommend to start with the documentation about splot and set dgrid3d.