[GRASS-user] Orthophotos in .sid - removing black border

GRASS GRASS user
,
1

Hamish wrote:

I may be dreaming, but I seem to remember writing a script to do that
some time ago (maybe March?) to crop the blank edges off the NOAA BSB
format nautical charts. try searching the archives and wiki.

see also the image classification modules, r.mask, and "g.region zoom=".

nope, not dreaming. see attached.

you'll have to adjust it to suit your needs, but the method works,
especially if the collars are square to the image bounds.

otherwise open the image in GIMP or whatever, use the magic wand select
on the border, set it to 0:0:0 or 255:255:255, reapply georef with
gdal_translate, reimport with r.in.gdal, use r.null to remove 0:0:0 or
255:255:255.

Hamish

(attachments)

decollar_noaa_charts.sh (2.51 KB)

2

So, I found the odd crs that the orthophotos were in used gdalwarp to
reproject the tiffs then wrote a script to bring all of the
orthophotos in and reclassed 0 as NULL, and poof the black border
disappeared. Now I need to combine the red, blue, and green images
into one single orthophoto for display. What would you use the three
color bands for anyway? Thank you all for your help.
regards,

Stephen Sefick

On Wed, Sep 16, 2009 at 2:40 AM, Hamish <hamish_b@yahoo.com> wrote:

Hamish wrote:

I may be dreaming, but I seem to remember writing a script to do that
some time ago (maybe March?) to crop the blank edges off the NOAA BSB
format nautical charts. try searching the archives and wiki.

see also the image classification modules, r.mask, and "g.region zoom=".

nope, not dreaming. see attached.

you'll have to adjust it to suit your needs, but the method works,
especially if the collars are square to the image bounds.

otherwise open the image in GIMP or whatever, use the magic wand select
on the border, set it to 0:0:0 or 255:255:255, reapply georef with
gdal_translate, reimport with r.in.gdal, use r.null to remove 0:0:0 or
255:255:255.

Hamish

--
Stephen Sefick

Let's not spend our time and resources thinking about things that are
so little or so large that all they really do for us is puff us up and
make us feel like gods. We are mammals, and have not exhausted the
annoying little problems of being mammals.

                -K. Mullis

3

Now I need to combine the red, blue, and green images into one single
orthophoto for display.

just use d.rgb or GUI equivalent.

If you must, use r.composite to combine them but it is recommended to not
do that if you can help it due to ...

What would you use the three color bands for anyway?

... maintaining fidelity.

Hamish