The Tariff DX Program

The DX programming was done in two steps:

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1. A simple program to read text-formatted data and convert it to a more compact DX internal format. The program and dialog boxes are shown below.

   

   The grid specification in the import dialog box indicates 100³ points. The majority=column indicates that the data was written in FORTRAN order, first index changing fastest. See section 2.1.3 for more info. The export module dialog box specifies a filename for storing the converted data and the default "dx" format.

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2. A program to convert the data to an image (Shown below).
   Several thing to note:
   • The import module reads the file that was written by the Export module in the first program.
   • The right-hand branch of the program (ShowBox-Tube-Color) generates a grey bounding box.
   • The left-hand branch:
     1. Selects either a low-pass filtered version of the data or the original data. Low-pass filtering smears the data a bit so that the next operations will correctly cut connections. The Compute module which controls the Switch causes raw data to be displayed if a zero minimum value is chosen using the Scalar interactor and filtered value of a nonzero value is chosen. The Compute module function is (a>0) ? 2 : 1
     2. The Include module marks as invalid any points lower than the minimum selected using the Scalar interactor. This marking has the effect of removing the points and their connections to surrounding points from the data set.
     3. Colors the data according to the colormap.
     4. Draws the boundary of the valid data. If the Scalar interactor is set to zero, all the data is shown as a solid cube. Set to a nonzero value, only the data positions with values greater than zero are drawn.
   • The two branches are collected together and rendered.

   Image with nonzero minimum set to 0.01.

   

   Image with a zero minimum which causes the exterior of the cube to be drawn.