World Wind NASA for developers
If you want to use WorldWind source code in your web base application then you need to follow the tiling scheme. It is completely opposite to Virtual earth mapping technique. Columns are west to east and rows move south to north. As we know, you can zoom in and zoom out. At that time it replaces normal resolution with 4 tiles higher resolution. This concept is called ZeroTileSizeDegrees (ZTSD). It helps in specifying certain level when to be displayed or when it gets hidden from user. In short it determines how to change zoom levels when user perform any action on the maps or images.
When user fully zoom the particular images, ZTSD show images with 45 to 36 degrees. If you don’t want to see a detailed view, you can zoom in by specifying a smaller ZTSD. For every image on WorldWind it uses EPSG 4326 projection. At this point, it is perfectly modeled as sphere. All this implementation is done with the help of QuadTile Class. Using this code is not as simple as it seems. However, by spending few hours to understand the logic, you can create your own Image tile services for your web application. Create a set that will only be used to call URL for a tile. Include logic to call appropriate row and column from WorldWind.
Create service that will correspond to level and convert in into appropriate resolution as per your website requirement. Just by adding few lines of code you will see the magic. It is just not a theory but proven practically by different map-based web application developer experts. Until now many developers has used the code and successfully launch their application. You need to concentrate on lining up correctly. Many developers have faced problem lining as sometimes it skipped the row of tiles resulting in getting wrong images on your web page. Using top-down approach is advisable other as it won’t jump correctly between different images.
There are number of community members of WorldWind NASA, who will give you tips about how to overcome this problem. The tips will enable you to show your map with right angle and great resolution. Finding an exact image with the help of right coordinates is bit complicated task. However, it is very challenging that makes it most interesting task. You may experience that taking images from WorldWind NASA is easier than virtual earth application as it is very complicated process. Just do not loss your patience and you will get great results as you want without any confusion as once you understand the process it becomes very easy.
Once you start working with the technique, you will be fully convinced that no other open-source application than WorldWind NASA will help you to this extent. As you start using it, you will experience more control over the application. It is advisable to start with Map projection plug-in that will give you a brief overview of the entire project. The World Wind NASA library will provide USGS that helps to convert Cartesian coordinates with different projection techniques. [tags]NASA, World wind features, World Wind use, [/tags}
Tags: NASA World Wind
