[GRASS5] r.contour bug with NULL data

GRASS GRASS developer
1

Hi all,

r.contour obviously fails if "no data" sections are
within a raster map:

r.contour -q in=dgm12.5 step=10 out=contour10
Error, 1 crossings in Cell 185, 157
Error, 1 crossings in Cell 188, 160
       
Help would be appreciated (or shall I put into RT?)

Thanks,

Markus

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2

On Fri, Jan 12, 2001 at 05:23:49PM +0000, Markus Neteler wrote:

Hi all,

r.contour obviously fails if "no data" sections are
within a raster map:

r.contour -q in=dgm12.5 step=10 out=contour10
Error, 1 crossings in Cell 185, 157
Error, 1 crossings in Cell 188, 160
       
Help would be appreciated (or shall I put into RT?)

.. correction: The modules finishes!
I have added a "Finished." message to be printed in case of
no *real* errors. Like that we don't get confused by above
crossings error.

It seems the contours are ok although Error, 1 crossings... is
printed.

So: no bug :slight_smile:

Markus

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3

Hi Markus

Markus Neteler wrote:

Hi all,

r.contour obviously fails if "no data" sections are
within a raster map:

r.contour -q in=dgm12.5 step=10 out=contour10
Error, 1 crossings in Cell 185, 157
Error, 1 crossings in Cell 188, 160

Help would be appreciated (or shall I put into RT?)

Speaking of "no data" sections of raster maps, a few years ago I wrote a
module called r.fill.null that scanned raster maps for "holes" in the
data. If it found any, it would average the surrounding cell values to
fill the hole using a 3x3 neighborhood. THis only works on small holes
but it did give us completely filled surfaces.

Do you think there is enough interest to add this to Grass?

--
Sincerely,

Jazzman (a.k.a. Justin Hickey) e-mail: jhickey@hpcc.nectec.or.th
High Performance Computing Center
National Electronics and Computer Technology Center (NECTEC)
Bangkok, Thailand

People who think they know everything are very irritating to those
of us who do. ---Anonymous

Jazz and Trek Rule!!!

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4

Hi Justin,

On Mon, Jan 15, 2001 at 07:12:48PM +0700, Justin Hickey wrote:

Hi Markus

Markus Neteler wrote:
>
> Hi all,
>
> r.contour obviously fails if "no data" sections are
> within a raster map:
>
> r.contour -q in=dgm12.5 step=10 out=contour10
> Error, 1 crossings in Cell 185, 157
> Error, 1 crossings in Cell 188, 160
>
> Help would be appreciated (or shall I put into RT?)

Speaking of "no data" sections of raster maps, a few years ago I wrote a
module called r.fill.null that scanned raster maps for "holes" in the
data. If it found any, it would average the surrounding cell values to
fill the hole using a 3x3 neighborhood. THis only works on small holes
but it did give us completely filled surfaces.

Do you think there is enough interest to add this to Grass?

Definitely! I was searching for such a tool recently to fill holes in
raster maps. Perhaps you tool could be taught to fill any hole size?
Or one has to run it several times..

Yours

Markus

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