Version 32 Newsletter
The format for additions/changes is being revised. The concept is to say more, ask for feedback and indicate possible future developments.
Kites and Darts
A kite is a four-sided convex polygons whose edge lengths in cyclic order are AABB. A dart is the same, but concave.
The number of kites and darts in a pattern has been added to the database. However, this has not been added to the comprehensive search since it is felt that the facility is already too complex.
The logic for this facility has not been changed for over three years. In consequence, after making all the choices requested, the final number of patterns can be over 150.
For this release, an upgrade has been undertaken which, in some circumstances, can ask if a pattern has a kite. The maximum number of patterns after all choices have been made is still 130 - so more work is needed!
Feedback would be welcome, since no record is made of the use of the tree search.
Many additions have resulted from the photos in Eric Broug's new book: [broug2]. The book also indicates other sources which have been scanned for suitable patterns.
An interesting pattern is A mosque in Aleppo. Unfortunately, the photographer did not record the actual mosque. As always, if anybody does find details of a pattern not recorded on the web site, we would be delighted to be informed.
The pattern Abdul Raouf Hasan Khalil Museum, Jeddah is very similar to another one in the National Museum in Copenhagen. We have been unable to establish the original sources. Most museums have excellent web sites which provides this information.
Patterns on domes are not usually possible, but Dome of the Prophet's Mosque has been included since the photographer was careful enough in positioning the shot.
Note that all of the new patterns can be displayed by using a text search for the string 'data198' with the comprehensive search (Tile search input).
This has been a problem for two reasons: the older material used random colours which sometimes gave a poor result, and many Islamic patterns have a source without much colour. For this release, an attempt has been made to re-do all the patterns with poor colour.
This tool allows one to modify the PDF graphics available from this site. Of course, such modifications does not change the PDF on the web site. The Open Clip Art Library has an example of the tiles used in Moroccan Islamic patterns which can be used to create many different patterns.
The basic search methods only handle regular tiles - regular polygons or regular star-polygons. However, an index has been produced to all the irregular tiles. This material has not been added to the web site since it is unclear how to present it in a reasonable manner. Instead, the index is used to produce other material for the web site.
Some patterns cannot easily be represented in a mathematical form used for almost all the patterns on this web site. An example of such a pattern is Bourgoin, Plate 134. It is not quite clear how these patterns should be handled, and suggestions would be welcome.
Variants of a pattern
We hope to produce a means of handling small variants of a pattern - ones with the same topology but variations in angles or lengths.