Regina Obe has just announced that PostGIS in Action book website launched. It is http://postgis.us
postgis dot us
Reply
Tag Archives: geography
PostGIS explains DE-9IM
I am happy I belong to the hordes of PostGIS users. Recently I asked for a very small addition to the PostGIS manual that will explain the three basic terms of the geospatial geometry: interior, boundary and exterior.
Kevin Neufeld delivered a very well written chapter about Dimensionally Extended 9 Intersection Model (DE-9IM) with series of excellent visualisations of the non-trivial mathematics.
Moreover, Kevin started completing the PostGIS Functions Reference with visual presentation of geometric problems together with SQL commands using various PostGIS functions that can be applied to solve particular situations. For example, what does the ST_Buffer function, how boolean predicates like ST_Contains check spatial relation of two geometries or what’s the difference between ST_Difference and ST_SymDifference.
Clearly, I’ve got way way more than I asked for or I expected. On behalf of myself and users who are about to start their adventure with PostGIS, I’d like to give big kudos to Kevin for this fantastic work!
Together with the recently documented PostgreSQL PostGIS Types and Function Support Matrix, PostGIS team is making abrupt manual a pleasant reading book.
By the way, here is a bunch of references about DE-9IM I found very useful myself:
- Dimensionally Extended Nine-Intersection Model (DE-9IM) by Christian Strobl
- Encyclopedia of GIS by Hui Xiong, page 242
Talking about data races
My countryman Bartosz Milewski – the author of one of the best C++ introductory books – the C++ In Action posted video with very interesting talk about Ownership Systems against Data Races (video is here).
Interestingly, Bartosz proposes to understand the battle with data races as a discipline-driven programming that helps, mostly C+ programmers, to avoid all this horrible pitfalls. Moreover, Bartosz presents programmers with a well-designed methodology based on types system as a tool that may guard programs against injury from data races problem and with success.
Basically (and not surprisingly) Bartosz recommends think first, act later kind of approach based on detailed analysis of what might be causing data races in your program, on identification of potential sources of data race problems. This approach is a contrary to spending hours searching for data races conditions using debugger.
The data race problem is a complex subject, but – in my opinion – Bartosz explains it in a very accessible step-by-step form. Three words summary of Bartosz’ lecture and the presented methodology is: sharing + mutability + no synchronisation = data race
Spatial Relations for Dummies
My friend Jo asked on GEOS mailing list for approachable explanation of spatial relations and Dale Lutz from Safe Software suggested something I’ve not came across myself before and what (in generalised form) I’d consider as a great idea for…a book really :-)
PostGIS In Action
It really must be very hot and fresh news, so the virtual devil spirit of social networking hasn’t fished it out yet and also Google (check this if you haven’t heard yet about this local family company) lists less than 15 pages.
PostGIS provides over 300 spatial operators, spatial functions, spatial data types and spatial indexing enhancements. If you add to the mix the complimentary features that PostgreSQL and other PostgreSQL related projects provide, then you’ve got one jam-packed powerhouse at your disposal well suited for hardcore work as well as a valuable training tool for spatial concepts.
Three words: PostGIS In Action. The first book about PostGIS spatial database being written by Regina O. Obe and Leo S. Hsu with release planned for the beginning of 2010. First chapter of the book has been published and is freely available as PDF file through the Manning Early Access Program. Chapter two and three are also available for MAEP subscribers.
Next to the early access, another cool thing about the way Manning Publications release their books is possibility to comment chapters and discuss with authors directly through Manning Sandbox forums. There is no exception for the PostGIS in Action :-)
Update 2009-05-08T23:08:21+00:00: The book official announcement has been posted on postgis-devel and postgresqlonline.com.
I’m looking forward to grab the book!
Pierre, check the TOC for chapter thirteen. Cool, isn’t it?
Geospatial bits on BoostCon’09
On the 3rd of May 2009, the best event dedicated to C++ programmers starts in Aspen, US. It is BoostCon’09. The conference gathers developers and users of Boost C++ Libraries.
This year the event brings some flavour of geospatial technologies. Barend Gehrels and Bruno Lalande – core developers – are presenting their Generic Geometry Library –
- a library for geometry and geography,
- being agnostic in coordinate space and dimensions,
- based on templates and static polymorphism,
- decoupling types from algorithms,
- applying (self)verification of specified requirements with use of concepts
uff. :-)
C++ Concurrency in Action
By the beginning of the year 2009, new must-read book for C++ hackers is rolling around. Anthony Williams is writing book titled: C++ Concurrency in Action (ISBN: 1933988770):
I will be covering all aspects of multithreaded programming with the new C++0x standard, from the details of the new C++0x memory model and atomic operations to managing threads and designing parallel algorithms and thread-safe containers. The book will also feature a complete reference to the C++0x Standard Thread Library.
from Anthony’s blog
Since June, Anthony’s book is available through Manning Early Access Program. The final release is planned on February 2009.
In the meantime, Anthony has published an article Simpler Multithreading in C++0x introducing multithreading support and thread library as a new feature in the C++0x standard.