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A program for finding and displaying rectangular structures in scanned excavation plans

Version 3.01

Thanks to collaboration with Karel Segeth, director of the Mathematical Institute of the Academy of Sciences of the Czech Republic, Prague, it has been possible to implement a Windows  programme for detecting rectangular structures in scanned excavation plans or from digitizer output. Karel has devised an especially fast algorithm and a set of data structures which make very fast searches possible.

The program deals with the problem described in:

M. Fletcher, G. Lock, Post built structures at Danebury Hillfort: An analytical search method with statistical discussion, Oxford Journal of Archaeology, Vol. 3, No. 2, 1984 p. 175-196.

Other shorter articles by them appeared in Science and Archaeology in the same year and in 1981. See the references in the article above.

Karel's algorithm is many times faster than the methods employed earlier. It completes in the order of seconds on several thousand holes. Karel wrote the original number crunching code in Fortran some years ago. He then modified it for dynamic data structures in Pascal. It has now been modified and optimized for 32 bit Windows by the undersigned.

A new automatic 'hole finder' helps you to mark all the holes in a scanned bitmap without having to deal with each of them individually. Some rather unusual pattern recognition techniques have been implemented for this function.

An industry-standard installation program installs the program to a directory of your choice and make a program group entry for it. There is a test scanned bitmap (test8bit.bmp) of part of an  Iron Age excavation in Germany along with the geometrically transformed posthole data belonging to it (test8bit.tdf). Fletcher and Lock's Danebury data (danebury.bmp)  is also included.  The data of test8 , in pure Ascii format as obtained from earlier hand digitization is also supplied (hole.asc) so that you can try fitting such data to a bitmap.

You don't need a digitizer to use the program. Interactive posthole entry from the scanned image on the screen is supported with considerable comfort and precision and the automatic finder will find and mark most of the holes for you.

The help file accompanying the program provides a short description of all functions.


Posthole.exe which is the installation programme. It will install Posthole under all 32 bit versions of Windows (NT/2000/XP/Vista).  

Run posthole.exe  as a member of the administrators group, otherwise an error message results.  This is vitally important under Windows Vista and all other versions of Windows so that permissions are set correctly on the installation directory.  All users may then access the program.

If you have installed an earlier version, make sure to uninstall or remove it **before** you install the latest version..  Use the Add Remove programme option from the Control Panel.

Posthole is in the public domain and may be freely copied and distributed.

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Last update: August 27, 2007