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*Screenshot (60k)

From a set of irregulary spaced data points with coordinates in the plane, a smooth surface is to be fitted to these points. Typical content of a point might be a count of the number of types at that point, representing the local richness of each point, with the surface estimating the distribution of richness over the entire area. If the content is the value of the position in a seriation, then the surface might represent a prediction of chronological distribution over an area. If the content represents presence in a cluster, then the surface might show the scope of each cluster. Any data which can be entered into Winbasp and which contains coordinate information can be displayed as a colored contour plot, a meshed shaded contoured surface or a number of other variants.

Contour diagrams of find abundances are easily constructed with the new three dimensional display program. Contours may also be filled with color and/or displayed as a shaded surface, if desired.

*Screenshot (16k)

Input/Output of Winbasp data:

Entry Output: *.ent, *.eck
For these you can display either a 3 dimensional colored surface map of attributes as a number (used as a rough Z coordinate) or counts of types in each unit. You may also display these as a stacked colored histogram at each point on a map. You can change the 3D surface to a 3D full histogram after it is displayed. You can also make a contour map superimposed on a scanned bitmap. An example of such a result can be seen by displaying the file tutorial.bmp from any bitmap viewer program.

Tools Output: *.ser, *.orw, *.clu
You can display all of the above from Entry plus:

The program makes .bmp, .wmf, .emf (Extended 32bit wmf) output, copies the image to the clipboard or sends it to the printer.

Test Data:
For testing, you may use the files Tutorial.* which are included here.

Customization of the Display:
You can customize the display yourself to add and change things in a very large number of ways. For example, you can make a 2D contour map, with or without color. Open the test file displa3d.oc3, and after admiring it, you can right click to bring up a tabbed dialog box which lets you customize nearly everything. The help file which can be called from the main menu explains all the details. It is from the supplier of the underlying graphics engine, KLG Inc. of Toronto, Canada.

You can change the mesh interval in the interpolation from the options dialog box when you choose new data. The default of 50 is a reasonable compromise between appearance and computing time. If you increase the density of the mesh, computing time rises as the square of the mesh number. You can change any of the values at any of the grid points from the tabbed dialog box. You can also change contour intervals and contour colours so that they can be seen more easily on a coloured scanned bitmap background.

The mouse-user interaction mode (also described in the help):

When you generate a 3D surface, Displa3D makes two intermediate ascii files called name.tmp and name.dat, where name is the name you have given to an input file.

The name.tmp file contains the x, y and z coordinates of the input data along with a header showing the number of input points, their maximum and minimum values of x and y plus the desired mesh interval.

These temporary files are processced by a stand-alone command line program called Ireg2Reg.exe which uses the file Akima.dll for its computation. It produces an output file called name.dat This file contains the data which has been interpolated onto a regular grid from any source of irregular gridded data. It may be imported directly into KLG's Olectra Groups --Data-- Load and displayed without loading the Winbasp data again. Similarly, you may save Olectra output data in either this format or in Olectra's proprietary binary format with the extension oc3. This contains all the parameters for the display plus the data, and reloads much faster than loading via the Winbasp input file. It has a small header which is needed by Olectra e.g. for Tutorial.dat:

GRID 40 40
  0.1287  0.1137
 -2.6197 -2.3201

The first line tells Olectra that the data is now on a regular grid, and that the grid spacing is 40 x 40 (and that 1600 grid values will follow below). The next line is a default 'hole' value, not used here, but required by Olectra. Then come the values of the x and y steps used by Olectra, and finally the minimum values of x and y which Olectra should use for labelling.

You may also use Ireg2Reg.exe in command line mode to produce digital elevation models from data presented to it in the format given by the .tmp file. Akima.dll must be in the same directory as Ireg2Reg.exe. Delete the Olectra header and use the .tmp file values for x and y coordinates if you wish. In this way, you may also use data which comes from outside Winbasp, although no checks for correctness of this data are made. You may also use the interpolated surface data in any other program which can accept it.

The interpolation technique is based on a biquintic polynomial interpolator on the triangulated irregular data due to Akima (ACM Algorithm 526 of 1978 with additions by Preusser in 1984). There is no limit to the number of data points permitted, but the algorithm may show instabilities and produce garbage if too many closely spaced points lie on circles or in straight lines. The algorithm is exceeding fast so that very large numbers of points may be used. The coordinates are slightly dithered on input so that instability in the Akima algorithm is reduced.

The calculations are carried out in the separate dynamic link library Akima.dll whose source code is compiled using the fastest optimizing Fortran compiler available (Watcom Fortran, ver. 10). Displa3D itself was originally written in 1996 in Borland Delphi 2.0 Object Pascal which permits passing dynamic array structures at runtime. A revised version for Windows XP was created in 2005 using Delphi 7

This is a 32 bit application which runs only under Windows 9x/ME or Windows NT/2000/XP. It will not run under 16 bit Windows even if you have installed Win32s. Run the installation programme disp3d.exe as a member of the Administrator group to install it under Windows 2000/XP. Permissions and rights for other users will be set automatically if you leave the box Set Rights and Permissions checked when the installation is finished.

You must have a registered copy of Winbasp Version 5 to produce real data for it, but you can run it with the test data provided to see what it looks like or use simple ascii file command line technique as described above for use with other programs.

The program and its components may be copied and distributed freely without restriction.

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Last update: September 4, 2005