Mechanical Engineering Home > Education: Courses > Shortcourses > Tecplot > Contours

Contours

Tecplot Data Formats

Tecplot can read in several data formats, including structured, unstructured or one dimensional (for graphs). These are ascii files that tecplot converts to binary using a program called "preplot". Tecplot can read binary files that have been created by "preplot" or created by your programs. Your progams should call FORTRAN or C functions supplied by Tecplot to write the data.

Structured Data

Structured data may be either 1, 2 or 3 dimensional. We will go through the 2-D data formats. The others are similar. You may use your favorite editor to add the headers to your data.

Spaces and blank lines are ignored by Tecplot and there are some short cuts that will eliminate a line or two from the header. See the manual if you are interested in the shortcuts. You may use either upper or lower case letters. Here is a mesh and the simple data file that produced it.

title = "sample mesh"
variables = "x", "y", "z"
zone i=5, j=4, f=point

 2.000000  5.000000 -19.178485
 4.000000  7.000000  26.279464
 6.000000  9.000000  24.727109
 8.000000 11.000000 -79.999217
10.000000 13.000000  42.016704
 2.000000  8.000000  19.787165
 4.000000 10.000000 -21.760844
 6.000000 12.000000 -32.194375
 8.000000 14.000000  79.248588
10.000000 16.000000 -28.790332
 2.000000 11.000000 -19.999804
 4.000000 13.000000  16.806681
 6.000000 15.000000  39.017270
 8.000000 17.000000 -76.911799
10.000000 19.000000  14.987721
 2.000000 14.000000  19.812147
 4.000000 16.000000 -11.516133
 6.000000 18.000000 -45.059235
 8.000000 20.000000  73.035620
10.000000 22.000000  -0.885131

The line "zone i=5, j=4, f=point" states that we have 20 points in our mesh, the mesh is 5 x 4. Note that the i index corresponds to the inner loop (the fast loop). That is we read the data points (suppose they are stored in the array A) as follows

              C Notation    Fortran Notation
 i=1, j=1      A[1][1]         A(1,1)
 i=2, j=1      A[2][1]         A(2,1)
 i=3, j=1      A[3][1]         A(3,1)
 i=4, j=1      A[4][1]         A(4,1)
 i=5, j=1      A[5][1]         A(5,1)
  .
  .
  .

Tecplot accepts other formats. If we change "f= point" to "f= block", then tecplot expects all the x coordinates, then all the y coordinates and finally all the z-coordinates. Here is "f= block" format of the above mesh.

             title = "sample mesh"
             variables = "x", "y", "z"
             zone i=5, j=4, f=block
             
             2.000000 4.000000 6.000000 8.000000 10.000000 
             2.000000 4.000000 6.000000 8.000000 10.000000 
             2.000000 4.000000 6.000000 8.000000 10.000000 
             2.000000 4.000000 6.000000 8.000000 10.000000 
             5.000000 7.000000 9.000000 11.000000 13.000000 
             8.000000 10.000000 12.000000 14.000000 16.000000 
             11.000000 13.000000 15.000000 17.000000 19.000000 
             14.000000 16.000000 18.000000 20.000000 22.000000 
             -19.178485 26.279464 24.727109 -79.999217 42.016704 
             19.787165 -21.760844 -32.194375 79.248588 -28.790332 
             -19.999804 16.806681 39.017270 -76.911799 14.987721 
             19.812147 -11.516133 -45.059235 73.035620 -0.885131 
 

In this format, the number of entries per line does not matter.

Unstructured Data

Tecplot can read in unstructured (finite element) ascii data. This data can be either two or three dimensional. We will go through 2-D data formats, 3-D is similar. You may use your favorite editor to add the headers to your data. Spaces and blank lines are ignored by Tecplot. You may use either upper or lower case letters. Here is a simple data file.

               title = "Sample finite-element data"
               variables = "x", "y", "a","b"
               zone n=5, e=4, f=fepoint, et=triangle
               
               0.0 0.0 1.0 2.0
               -1.0 -1.0 0.0 2.2
               -1.0 1.0 0.0 3.0
               1.0 1.0 0.0 3.4
               1.0 -1.0 0.0 1.1
               
               1 2 3
               1 3 4
               1 4 5
               1 5 2

               x y a b
               x y a b
               x y a b

                That is, there is a line for each point                and each line contains 4 numbers.  

If we had used "f= feblock" instead, then Tecplot would expect all the x-coordinates first, then all the y-coordinates, followed by the a's and finally the b's. That is,

             x x x x .... x
             y y y y .... y
             a a a a .... a
             b b b b .... b
             
 

The title may be omitted.

One Dimensional

For graphs, tecplot has several data formats. Only the simplest one is described here.

The simplest data format that tecplot for graphs is a list of points. For example:

             x1 y1
             x2 y2
             x3 y3
             .
             .
             .
 

No header is necessary. You may have more than two coordinates per line. For example

               x1 y1 u1 v1 
               x2 y2 u2 v2
               x3 y3 u3 v3
               .
               .
               .
             

From within tecplot, you can then select the variable to use for the x-axis and the variable for the y-axis.

Multiple Zones

Tecplot allows your data files to have more than 1 zone. All you need to do is add a line similar to the line that starts with zone as in the above examples to your data file. The data following the zone defines the zone. Any or all of the zones may be displayed.