Archive for the ‘general’ Category
GIS Servers and the 64-bit Question
The following is the first in a series of posts related to configuring a 64-bit Windows server as a GIS server using MapServer and Python.
Why move to 64-bit?
If a server’s operating system and hardware are 64-bit it seems a waste not to take advantage of them. It may be better to look at the question why move to 64-bit software, as why wouldn’t you move to 64-bit software?
Its nice to be able to claim one-upmanship over commercial GIS products who are only now bringing out 64 bit versions. However having gone through the pain of setting up Open Source GIS applications on Windows I’m not surprised companies took the time to simplify the process (and wait for Microsoft to do some of the legwork) rather than dealing with all the 32/64 bit support issues too early.
Source Control using BitBucket
Putting code under source control is on most checklists for modern software development. Even small side projects, scripts, and code snippets can benefit from being under source control. For example:
When you improve the code others can see the changes and get the benefits- If someone else improves the code those improvements can be passed back to you via an automated process
BitBucket is a hosting service for the code-source control system Mercurial. Mecurial is part of a new-wave of distributed source control systems that have the following advantages and disadvantages over regular non-distributed source control:
OpenAerialMap
Everyone loves aerial photography. Some of its early pioneers were the James Bonds of their era. Twenty years ago people could go round neighbourhoods in England and sell people frames photographs of their houses from the air.
Today people spend hours looking at the aerial photography layer on Google Maps wondering why so many people have outdoor swimming pools in the UK..
People also like free data. And companies like data free from the Google Terms of Service even more. The successful OpenStreetMap wiki refers to what seems to be the perfect datasource – the OpenAerialMap (OAM) project, however it starts with the rather ominous opening statement:
It was available at http://openaerialmap.org/ but…
Summary of Hours by Month (for every day)
I recently read Mark Forster’s time management book Do It Tomorrow. In summary it suggests creating a task list on a daily basis, and not doing anything other than from items in that list. Only real emergencies should be dealt with.
If emails arrive that have to be dealt with then add them to tomorrow’s list – that way you have a chance of completing your tasks for a day, and can switch off the computer feeling that you’re finished for the day.
There is also a chapter at the end of the book that says anytime invested in improving systems and processes is time gained. This fits in with the ethos of many programming books – to automate things as much as possible.
As I work on a number of different client projects I use a time tracking database to enter hours worked on a daily basis. It is fairly trivial to get a summary of hours for a month, but what I needed to provide (for invoicing) was a full list of days in a month and hours worked – whether there were values or not.
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Stack Overflow & OSGeo
Stack Overflow, as most developers will already know, is a question and answer site for programmers. It’s perfect for mainstream development questions in any programming language, and has also become the support site of choice for some newer programming communities such as Android developers. 
It can also be used as a barometer to see which current open source GIS projects have gained traction in the mainstream programming world. I took the full list of OSGeo projects from http://www.osgeo.org/ and ran queries on the site to see how many questions there were for each project. The results are as follows (as of May 2010):
Map Pins…
I wanna hang a map of the world in my house. Then I’m gonna put pins into all the locations that I’ve traveled to. But first, I’m gonna have to travel to the top two corners of the map so it won’t fall down.
Automated Diagrams and Documentation
As I previously wrote, one of the ways to get through the task of documenting a project is to turn the documentation process into a coding project. Documentation sometimes seems pointless as the likelihood of anyone other than yourself reading it are low to nil.
To increase the chances pretty pictures always help. If they are also useful then the documentation starts to have real value. Up until now I’ve been using Microsoft’s Visio, but recently I tried out a couple of online tools.
Class Diagrams
The MapServer Mapscript documentation currently uses of diagrams made from ASCII text to illustrate relationships between classes. I’m not sure if these were generated automatically, but the images now appear a little dated. They do however have the advantage over an image of being able to copy and paste class names.
+-------+ 0..* 1 +-------+ | Class | <--------> | Layer | +-------+ +-------+
I tried to recreate these diagrams using the online service http://yuml.me/. On the site you enter your model description using a fairly basic syntax. From then on the same diagram can be accessed using different URLs, which are used to control display and formatting options.
The diagram above was created using the syntax below. You can play around with this sample by clicking here.
[Hashtable]1..1->1[Class{bg:yellow}],
[Label ]0..1->1[Class],
[Style]0..*->1[Class],
[Class]0..*->1[Layer{bg:green}]