G_make_aspect*_colors() in lib/gis/color_asp.c is broken. It chooses
(defaults to?) a greyscale ramp, rather than what is expected for aspect
maps.
Verified with r.slope.aspect and r.colors.
--
Brad Douglas <rez touchofmadness com> KB8UYR
Address: 37.493,-121.924 / WGS84 National Map Corps #TNMC-3785
Brad Douglas wrote:
G_make_aspect*_colors() in lib/gis/color_asp.c is broken. It chooses
(defaults to?) a greyscale ramp, rather than what is expected for aspect
maps.Verified with r.slope.aspect and r.colors.
It creates a black->white->black double ramp, with the half-way point
being black. This will do the right thing, provided that your aspect
map covers the full range of possible values (e.g. -180 to 180 or 0 to
360), but won't work if a the extrema are absent.
--
Glynn Clements <glynn@gclements.plus.com>
On Thu, 2006-07-06 at 04:21 +0100, Glynn Clements wrote:
Brad Douglas wrote:
> G_make_aspect*_colors() in lib/gis/color_asp.c is broken. It chooses
> (defaults to?) a greyscale ramp, rather than what is expected for aspect
> maps.
>
> Verified with r.slope.aspect and r.colors.It creates a black->white->black double ramp, with the half-way point
being black. This will do the right thing, provided that your aspect
map covers the full range of possible values (e.g. -180 to 180 or 0 to
360), but won't work if a the extrema are absent.
That's not how it used to work and is down right confusing to examine
visually. Each "direction" used to have a distinctive color assigned to
it.
--
Brad Douglas <rez touchofmadness com> KB8UYR
Address: 37.493,-121.924 / WGS84 National Map Corps #TNMC-3785
On Jul 6, 2006, at 12:31 AM, Brad Douglas wrote:
On Thu, 2006-07-06 at 04:21 +0100, Glynn Clements wrote:
Brad Douglas wrote:
G_make_aspect*_colors() in lib/gis/color_asp.c is broken. It chooses
(defaults to?) a greyscale ramp, rather than what is expected for aspect
maps.Verified with r.slope.aspect and r.colors.
It creates a black->white->black double ramp, with the half-way point
being black. This will do the right thing, provided that your aspect
map covers the full range of possible values (e.g. -180 to 180 or 0 to
360), but won't work if a the extrema are absent.That's not how it used to work and is down right confusing to examine
visually. Each "direction" used to have a distinctive color assigned to
it.
Brad - that is what we have in the rst programs. But for historical reasons,
r.slope.aspect has the old greyscale color table - when I did the colored aspect
color table for rst there were already too many users used to the greyscale aspect map
produced by r.slope.aspect that I did not want to change it (I am talking about early 90ies here).
Now, when we have the shaded relief module maybe we could unify the outputs
from rst and r.slope.aspect, but I would leave for the next release,
unless others feel that it should be done now.
Helena
--
Brad Douglas <rez touchofmadness com> KB8UYR
Address: 37.493,-121.924 / WGS84 National Map Corps #TNMC-3785_______________________________________________
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