BirdView

UNDER CONSTRUCTION

Introduction

BirdView is an interactive web-browser embedded application that allows users to look at the available data in the flysafe database in an easy and intuitive way. It is built using the Google Earth browser plugin, which enables it to make use of all the Google earth GIS functionality (pan, zoom, high quality satellite images, etc), and combine it with the ease of a web browser. It can be found at http://public.flysafe.sara.nl/birdview.html.

Requirements

To be able to use BirdView, you need to fulfill a couple of requirements. Most of these requirements are usually already fulfilled, or in case of installing Google Earth browser plugin, very easy.

• You need to run either Microsoft Windows or Maxc OS X 10.4+ as operating system.
• You need to have a a compatible web browser. Internet explorer and Firefox are known to be compatible, but Firefox is recommended since it provides most functionality.
• You need to have the Google Earth plugin installed. This can be done very simply provided you have administrator rights.
• You need to have correct Video Drivers installed. If not, BirdView might be slow or even crash.
• You are advised to have sufficient memory. 1GB or more memory is recommended.
• You are advised to have a sufficient high speed internet. BirdView gets its data from a central server, and so data must be transfered. A slow connection means slower refresh time. 1Mb connection should work, but higher is recommended.
• To retrieve data, you need both a login and your IP-address must be registered. See BirdView#Security for more details.

Note: As of 21-04-2009 BirdView is not working in Internet Explorer 8. This issue is because Google Earth plugin itself is (temporarily) incompatible due to repairs. Tijs

Design

In the design of BirdView we have chosen to keep everything as modular as possible, dividing functionality between several separate components that each provide part of the data required in BirdView. We use the kml data format to transfer information between these components, and the BirdView html front-end. The modular design has several advantages, such as:

• Easy reuse of components
• Load balancing: Each component that provides data can be run on a seperate machine.

The components of BirdView can be divided into two categories, the front-end, client-side components, and a back-end, server-side components. ie the HTML front-end, the Javascript interaction handling scripts, and the data serving CGI/Python scripts.

HTML Front end

The HTML front end can be found at http://public.flysafe.sara.nl/birdview.html. The reason that the front end is publicly accessible is because the browser plugin does not work with secure html. As a compromise, the front end is

Control Panel

BirdView

In the BirdView tab you can find most of the interface controls for selecting the data in the FlySafe database. It allows you to specify the date and time your interested in, the radar beams you want to include in your queries, the bounding box for the meteorological data, and allows you to switch part of the visualization off and on as desired. Below we go into more detail on different parts of the interface.

Time Control

The topmost 3 fields, named "Date/Time", "Minutes" and "Animation", and their related buttons, are used to navigate trough time, and enable the user to quickly and easily find periods of interest, such as heavy migration.

When BirdView is started, the date and time default to UTC, rounded down to the hour. UTC is used, because the data in the database uses UTC timestamps, and by using UTC we avoid confusion as to timezones and daylight savings.

To navigate trough time, there are two options:

• To go to a specified date and/or time, you can simply fill in a specific date/time in the box, and press the "go" button. The data in BirdView will automatically update for the new period.
• To move backward and forward trough time, you can use the back and forward arrow icons respectively. The amount of minutes in the box is the size of the time-steps. The data in BirdView will automatically update for the new time-step. The default time-step is 30 minutes, equal to the time between consecutive radar images.
• The animation controls can be used to let BirdView Automatically play trough consecutive time-steps. It uses the same size of time-steps as the "back/forward" controls. The interval in seconds between steps of the animation is equal to the number in the box. Default is 3 seconds, but if large data selections are made, it is recommended to take a larger interval for the animation. The animation can be started and stopped with the play and pause button respectively.

Radar Selection

Currently there are three different MPR radars (Glons, Wier and Millingen) in the database, that each have both a high beam and a low beam, making a total of 6 different radar images each update.

Often when you are looking at the MPR data you only want a few of the radar images available. Therefore each radar (both low and high beam) can be selected individually. This limits the amount of information on your screen, giving a better overview. Furthermore, it reduces the loading strain, since only the data of the selected radars is retrieved from the database.

The radar selection is used for the following visualization options:

• Bird tracks
• Bird Summary Plot
• Radar Images
• Land Mask
• Rain Mask

Bounding Box

The FlySafe database contains a large collection of meteorological data, including wind speed, temperature and precipitation, for an area covering Scandinavia to North Africa. For looking at continental migration, this data can be an invaluable asset, but it also puts a strain on the database, since loading large areas can result in long loading times. If you are only interested in the weather in the Benelux, the long loading time is quite annoying. Therefore we provide an interface to specify the area of interest. In this interface the user can set a bounding box by providing the minimum and maximum latitude and longitude coordinates. This way, only the meteorological data inside this area is queried and displayed.

In some cases the meteorological data also has different values at different pressure levels in the atmosphere. For example, on lower pressure levels (i.e. higher in the air) the wind direction and speed can be significantly different compared to closer to the ground. Since birds can fly on different heights, this is can be an important factor when looking at bird migration.

These settings are used for :

• Wind Barbs
• Precipitation
• Temperature

Bird Tracks

The temporal extent of the MPR data in the FlySafe database is limited to 10 radar revolutions every half hour. Out of every half hour, 10 consecutive radar revolutions are taken, and on this data the ROBIN algorithm is used to extract the echoes that are considered to be birds. The algorithm then connects the echoes that it considers the same bird, resulting on small bird tracks of up to 10 different points.

By selecting the Bird tracks option, the bird tracks for all selected radars are shown. The low beam birds are shown in red, and the high beam birds are shown in green. There currently is no mechanism to identify which bird belongs to which radar, only the high and low beam distinction is made

Bird summary Plot

The bird tracks give an indication of the amount of birds detected by the MPR radar, but not of other characteristics, such as average speed and heading for each track. In order to give an good indication of these factors, a a dynamically generated bird summary plot can be shown. In this plot, the average speed and heading of each bird track is plotted on a circular graph. The angular component is the average heading, the radial component is the average speed, and the color is the density of birds on that part of the plot.

The plot itself is dynamically generated by a seperate R [www.r-project.org (R statistical language)] process, which can run preloaded R scripts. In this case, a bird summary plot is generated that gives a general indication the direction and intensity of bird migration. It is possible to write other R scripts that generate different kind of plots. These can be inserted in

If multiple radars are selected

MPR Images

Each Radar image is split up in different layers according to certain defining algorithms. The first image "Radar Image" is the full MPR image, colored for density of the echo. The second image "Land Mask"

The MPR images come in three different levels:

• bottom is the full echo density image, and this is collored in a range from green to red, where red is the most dense echoes.
• The middle level is the Rain Mask, which is shown as a Blue layer.
• The top level is the Land Mask, which is shown as a Green layer.

Each layer can be turned on and off individually, in order to look at different deatails of the radar image.

Temperature

The temperature is shown as slightly transparent filled contourplot, in an area bounded by the bounding box. The temperature range displayed is light blue to dark blue for the -20 to 0 degrees celsius range, and light green-yellow-red-purple for the 0 to 40 degrees celsius range. The effect is that the zero degree boundary is easily visible because the shfit from dark blue to light green. Additionally, each level of the contour represents a step of 0.33 degrees celsius and is bordered by very thin line, that aim to help seeing different temperature layers.

The temperature legend can be foun under the "Legend" option.

Credits

In this overview tab the main partners in the FlySafe Project are listed as images. Each image is a link to the organizations website, and a mouse-over shows the name of the partner.

Furthermore, there is a checkbox that switches on the logo-icons in the Google earth plugin. These icons show the location of the the partners on the map. The logo-icons are visible when you start BirdView, but are turned off automatically after 10 seconds.

Security

The security of the FlySafe database is an important issue, and as such there are a few security measures in place to protect both the data in the database, and the system itself.

The BirdView application itself is open to the public, and can be accessed by anyone. However, to access any kind of data from the database, a user requires two things:

• A username and password
• Your IP-address should be registered

If you are reading this page,

Known problems/Troubleshooting

Not getting data

If you do not get a popup for your username/password, and you did select data sources (for example, windbarbs and a date last week), chances are that your IP is not allowed access on the server. You can check this by going to the flysafe server on https://services.flysafe.sara.nl. If you get an "access forbidden" with error number 403, then you know this is the case. Please mail support for access.

Internet explorer 8

Internet explorer 8 is currently not supported by the Google Earth browser plugin. This is a temporary situation, but Google has not stated for how long. It has been disabled for about a month, and there is no indication when this situation will be fixed. The best solution till then is to install [www.mozilla.com/firefox Firefox].

Certificate is refused

The first time that you access the database in the BirdView application, you get a popup about the certificate being from unknown origin. In most cases, accepting it by clicking "yes" should give you the username/password prompt. However, under Windows Vista and in some cases windows XP as well, the certificate popup keeps appearing. Its assumed that the security setting in windows are to heavy and or bugged.

The fix luckily rather simple, and involves adding a root certificate to your browser that accepts the certificate of the FlySafe database. It might be possible that you need Administrator right to do this. Just click the link below, and select "trust this CA to identify websites". Install NIKHEF root Certificate This should work, but to be absolutely sure, you can also right click and save the link, which should give you a file named DucthCA-cacert.pem. If you open this file, and choose "Install certificate", then windows should automatically start a wizard that will install the certificate in the correct place.