The input for visualization is a dataset (typically in the form of an image, but could for example be a list of X,Y,Z values) that contains a specific value (depth, elevation or any other magnitude value) for different pairs of latitude and longitude.
The output is a WorldWide Telescope Collection which is a pyramid of images. The lowest level of this pyramid is the one at the maximum supported level of zoom. The upper levels correspond to the lower levels of zoom. The process of converting the input into a collection requires the following steps:
Process the Input
Input data should be read into a data structure that is capable of efficiently looking up a value given a pair of latitude and longitude values. For most datasets, a two-dimensional array indexed by latitude and longitude values will suffice. The SDK requires that the input be regularly gridded which means that the data should be read into a two dimensional array indexed by latitude and longitude, where each pair of neighboring latitudes has the same delta. Similarly, for longitudes.
Build the Base Image
The base image is the lowest level of the pyramid. At this level there are (2^ Level) * (2^Level) images. Each of these images is 256×256 pixels in size. This image can be built at any desired level of zoom.
Fill the Tile Pyramid.
Filling the pyramid is the process of building upper levels of the pyramid. This is accomplished independent of the data by using the base image. Every four neighboring images at the base level are aggregated to form one image at the current level. This is recursively done for all the levels.
Generate a Plate File.
A Plate file contains every tile of the pyramid, and a header section encodes the format of the pyramid. The purpose of this single file is that it enables much easier copying of the pyramid, to send to a colleague, make a backup, or any similar purpose.
Generate a Thumbnail Image.
The thumbnail image that appears in the upper panel of WorldWide Telescope should be created now.
Generate a Collection File.
A collection file (
*.wtml) is the XML metadata file that WorldWide Telescope uses to load the images generated. For more details refer to WorldWide Telescope Data Reference Guide.