[GRASS-user] ps.map: vlines use of attributes [UPDATE]

[Rich Shepard]

On Fri, 3 Jul 2020, Rich Shepard wrote:

> I'm preparing maps of fish distributions within a river network. For a
> couple of species there are two stocks of interest, i.e., green and white
> sturgeon and fall and spring chinook salmon. For both pairs some parts of
> their distributions overlap and I want to display both the distinct and
> overlap reaches. Each species/stock has its own data file.

> If not I guess it is a matter of trial-and-error on my part.

Trial-and-error results:

Use of the offset attribute of one vlines and adjustment of the line widths
produced acceptable maps where the distributions of the two fishes can be
distinguished.

The offset attribute is marked as 'experimental' and I've a suggestion for
an enhancement of this feature: allow a negative offset to set that line to
the other side.

On my maps one species distribution was overlaid on the underlying
hydrography layer while the other species was offest to the east a couple of
pixels. Ideally, each would be offest 0.5 pixel on either side of the
hydrography layer.

Rich