3.4. Changing view parameters

Contours must be re-calculated by the server when the contour parameters (levels, mode or smoothness) change. However, as contour rendering is done on the frontend, any changes to the contour rendering parameters (visibility, opacity, thickness, colour, line style) do not require any server interaction.

Similarly for raster images: As all the rendering is done on the frontend, any changes to the raster rendering configuration (colour map, range, scaling type) do not require any interaction between frontend and backend:

Vector overlay rendering requires image data for both the vector angle (normally calculated from polarization angle PA) and length/intensity (normally calculated from polarized intensity PI). The image data is first downsampled on the backend using block downsampling with an even block width, and then masked with a threshold value. Adjusting the block width or threshold value will require the data to be recalculated and streamed by the backend. The backend streams data tile-by-tile.