velvect: Plot representation of a velocity field
Package: plot
Usage
velvect uimage vimage
Parameters
- uimage
- Name of image containing u components of the velocity field.
- vimage
- Name of image containing v components of the velocity field.
- device = stdgraph
- Output device for plot.
- title = "imtitle"
- Title to be centered over the plot. By default, it will be the title from the image header of the uimage.
- append = no
- Append to an old plot?
- verbose = yes
- Print warning messages?
Description
Task velvect draws a representation of a two-dimensional velocity field by drawing arrows from each data location. The length of the arrow is proportional to the strength of the field at that location and the direction of the arrow indicates the direction of the flow at that location. The two images uimage and vimage contain the velocity field to be plotted. The vector at the point (i,j) has:
magnitude = sqrt (uimage(i,j)**2 + vimage(i,j)**2)
direction = atan2 (vimage(i,j), uimage(i,j))
Examples
1. Make a vector plot from the two images "crab.blue" and "crab.red".
cl> velvect crab.blue crab.red