Website Technology
This page is a preliminary page describing how we created the website, interactive maps, and panoramic photos. Individual sections will be expanded over the next few weeks and the page might be split into a number of shorter pages.
Contents
Main Website Architecture
The website design is based on a set of pure CSS templates from Website Style. The site runs on Apache and FreeBSD hosted by Pair Networks. Small amounts of PHP 5 and Javascript are used to implement features such as the contact form.
Interactive Maps
The interactive maps use a combination of technologies. It quickly became apparent that both Google Maps and Virtual Earth simply do not have the required detail in the study area. Therefore we had to create our own maps.
MapServer was chosen as our main map serving engine. This is an open source package that is very powerful and flexible, but it can be difficult to install. MapServer serves the Outline map, ASTER Satellite image, and Synthetic Stream data to the browser as a series of map tiles.
The webpage uses OpenLayers to control the map. This is an open source Javascript client that can receive online maps from a variety of sources. OpenLayers receives the map tiles from MapServer using WMS and also implements a cache for faster response times. As well as the WMS layers, OpenLayers reads two layers (Icons and Our Map Survey) from KML Files. Map data that we acquire in the field will be converted to KML using a mixture of text editors and file conversion utilities. Finally, the grid layer is 'manually' drawn using Javascript.
A second version of the map uses a Microsoft Virtual Earth base map instead of the MapServer Outline base map. OpenLayers is very flexible and can easily incorporate a Virtual Earth layer, although support is currently limited to v4 and earlier. Virtual Earth adds better coverage of wider Costa Rica, but lacks detail in the study area.
The Outline Map layer shows country and administrative boundaries. These are shapefiles that are available from the US Centers for Disease Control as a part of their Epi Info™ system.
The ASTER Satellite Image layer is a near infra-red daytime image taken by the ASTER imaging instrument flying on the NASA EOS Terra satellite. The image that we have used is taken from the ASTA Volcano Archive (AVA) for Arenal. These images are available via Smithsonian's Global Volcanism pages for Arenal. It was acquired on 29th August 2005, and has a Granule ID of SC:AST_L1A.003:2030725270.
The Synthetic Stream layer plots rivers, creeks, and streams that have been derived from DEM (digital elevation model) data. Ie. these are theoretical river positions based on height data. This works well for hilly areas, but it is poor for flat and low gradients areas. The data was calculated by the Inter-American Biodiversity Information Network (IABIN).
All of the blue map icons have been supplied by Sue Pichotta of Icons-Icons.com. All of these icons remain © Copyright 2008 Icons-Icons.com.
GPS Data Acquisition
All of the groups are equipped with GPS devices for basic navigation. The mapping group are using a Trimble GeoXM handheld field computer with integrated GPS. They will be using this to acquire the boundary and grid base point; acquiring new map features; and accurately locating survey points for the other groups. The GeoXM is essentially a weatherproof Pocket PC with an extremely good GPS receiver and antenna. The GeoXM is capable of 6m accuracy. After post-processing (differential correction) this improves to 1m without obstructions. In contrast, a typical consumer GPS is accurate to about 16-30m. We are using Trimble GeoExplorer on the GeoXM. The laptop 'back at base' is running Trimble GPS Pathfinder Office for post-processing and data management.
The GeoXM was supplied by Cody Cantrell of Western Data Systems. Many thanks to Cody who spent a number of hours with us taking us through the Trimble software.
Panoramic Photographs
We intended to produce the panoramic photographs using RealViz Stitcher. RealViz were purchased by AutoDesk in early May, and the Stitcher product range is temporarily unavailable whilst the product line is re-branded. This unavailability has been expanded beyond the initial estimate from AutoDesk and we have been forced to use a different product. We have chosen the Canon PhotoStitch product for the 2008 field season. The advantages of this are that we have it already, it is simple to use, and it works. The features are relatively limited, so we may choose to use AutoDesk Stitcher in 2009.
Photographs will be acquired using a Canon (EOS) Rebel XTi Digital SLR fitted with a Sigma 10-20mm wide angle lens set to 20mm. We shall also have a Canon 35-105mm lens for single shot photographs. The camera will be mounted with a Panosaurus panoramic head. This is an affordable panoramic head, and experiments in the backyard have shown that it is sufficient for our needs.
Blog
The Blog is implemented using Movable Type v4.1 (Personal). The style is modified from the standard Minimalist Green style.
