Convert a vectorial raster field into streamlines. The output is in a convenient GeoJSON format compatible with d3js mapping.
To use with npm, just type
npm install raster-streamlines
To create the streamlines, a vectorial field is needed:
var srteamlines = require("raster-streamlines"); var properties = srteamlines.streamlines(u, v, geotransform, density, flip);
- u is the speed in the x coordinates, where positive numbers go from right to left, as in the wind conventions
- v is the speed in the x coordinates, where positive numbers go from lower to upper, as in the wind conventions
- u and v must have the same dimensions, obviously
- geotransform is a six elements array, as defined in the gdal library. It's an optional parameter, the array position coordinates are used if the array is not given
- density is an optional parameter that changes the number of streamlines. When is 1 (default), the number is aprox. 60. If lower than 1, the lines will be fewer
- flip is an optional parameter to change the v speed direction if set to true
When using directly in HTML, use the rastertools as the namespace
rastertools.streamlines(u, v, geotransform, flip);
See this block for a real world usage.