_______________________________________________________________________________ This README file is part of the 3D Alpha shape software distribution. The software currently consists of four programs: Delcx --- 3D Delaunay simplicial complex Mkalf --- 3D Alpha shape file and data structure Alvis --- 3D Alpha shape visualizer Volbl --- Measuring unions of spherical balls and voids The distribution includes the Silicon Graphics executables of the corresponding programs and some sample data sets. The executables require IRIX 5.1 or higher, and a system configuration with 32 Mb main memory, or more, is recommended. The programs usually understand several command-line parameters. To obtain a list of them, including their syntax, just execute the code without any parameters; for example, to get the usage information of Alvis, just type % alvis at the Unix prompt. _______________________________________________________________________________ DOCUMENTATION The 4.0 distribution includes a help directory with the following files: Copyright ...... Copyright and licensing information. Install ........ How to install the software. README ......... This file. README.input ... File format of input data. README.delcx ... README file for the Delcx program. README.volbl ... README file for the Volbl program. Tutorial ....... Brief introduction to Alpha shapes and Alvis. Includes a short description of 3D Alpha shapes and a guided tour through the user interface of Alvis 4.0. REFERENCES ..... List of references, as cited in the above documents. About .......... Author information and acknowledgements. (*) Bindings ....... Key bindings of Alvis user interface. (*) Parameters ..... Alvis command-line parameters and default settings. (*) Signatures ..... Implemented signature functions. (*) (*) Also available as Alvis on-line help. Please read the above files for the corresponding information; in particular, make sure that you read the files Copyright, Tutorial, and README.input. The remainder of this file covers the topics - Alvis output files and - User feedback. _______________________________________________________________________________ FILES Alvis reads three input files, namely, ....... the coordinates of the input data (see README.input), .dt .... the Delaunay complex (as produced by Delcx), and .alf ... a representation of the Alpha shape family (see Mkalf). Optionally, it produces several output files. Their format is described below. _______________________ RGB Files (*.rgb files) Alvis outputs image files in SGI's default RGB format for the drawing and signature windows. The RGB files for the drawing window are named ..rgb, where denotes the sequence numbers (0001, 0002, 0003, etc.). The RGB files for the signature window are named .sig..rgb. _________________________ Simplex Lists (*.sl file) Alvis outputs the simplex list of the currently displayed shape, which can be an alpha shape, a void or collection of voids, a pocket or collection of pockets, etc. The produced output file contains exactly the simplices currently displayed and is therefore sensitive to the setting of the simplex matrix in the control panel. The file contains ASCII text. It is named ..sl, where is the first unused number in the sequence 0001, 0002, etc. The format is line-oriented: the first two characters identify the type of the simplex, and they are followed by a list of up to 4 indices referring to the points in the input data file that form the vertices of the simplex. # text Header-lines with some self-explanatory information, including name of input data file, Alpha value, rank, and number of simplices to follow. iT %d %d %d %d Tetrahedron. iF %d %d %d Interior triangle. It is shared by two tetrahedra in the current shape. rF %d %d %d Regular triangle. It bounds one tetrahedron in the current shape. It has positive orientation: choose the normal vector such that its tip sees the three vertices making a counterclockwise turn; this vector points towards the outside of the shape. sF %d %d %d Singular triangle. It belongs to the current shape but is not face of any tetrahedron in the shape. iE %d %d Interior edge. The triangles and tetrahedra in the shape that contain the edge completely surround it. rE %d %d Regular edge. It is not interior and belongs to at least one triangle. sE %d %d Singular edge. It belongs to the shape but is not face of any triangle or tetrahedron. iV %d Interior vertex. The edges, triangles, and tetrahedra in the shape that contain the vertex completely surround it. rV %d Regular vertex. It is not interior and belongs to at least one edge. sV %d Singular vertex. It belongs to the shape but is not face of any edge, triangle, or tetrahedron. _____________________________ Signature Values (*.sig file) Alvis outputs one line of the current signature values displayed in the signature panel. The file is in ASCII format. _______________________________________________________________________________ USER FEEDBACK If you find any bugs or problems in using Alvis, please tell us by sending an email message to our contact address given below. If you want to see more software like Alvis, or improved versions thereof, we encourage you to inform us by letter or email, telling us what you are doing or envision doing with Alpha shapes. The following information would be helpful: 1) What area do you work in (an abstract of your work would be nice). 2) How did Alvis help you or how might it help you in the future, with additional functionality implemented. Contact address: We encourage citation of Alvis in your publications. A bibliography of your work would be appreciated.