[GRASS-user] patching dems together

[stephen sefick]

Markus,
I made a Permanent Map set and put in everything from the projection
region, and followed your directions.  They worked.  I have created
the map, and I am now reprojecting it into another mapset so that I
can use v.strahler to calculate stream orders.  Thank you so much for
your help.  As it is most of the time- I think it was operator error.
Sorry, for the headache.

Stephen Sefick

On Thu, Jul 9, 2009 at 2:55 PM, Markus
Metz<markus.metz.giswork at googlemail.com> wrote:
> stephen sefick wrote:
>> yes still 0-296.  I think the problem is this
>>
>> r.info -s series_map
>> nsres=1:09:25.8
>> ewres=1:01:15.8736
>>
>> however:
>> g.region -p
>> projection: 3 (Latitude-Longitude)
>> zone:       0
>> datum:      nad83
>> ellipsoid:  grs80
>> north:      34:23:38.999997N
>> south:      30:23:31.999996N
>> west:       84:31:21.99999W
>> east:       79:25:00.999989W
>> nsres:      0:00:01
>> ewres:      0:00:01
>> rows:       14407
>> cols:       18381
>> cells:      264815067
>>
> Hmm, doesn't make sense if you have set this region before patching. I
> guess now you must post the exact commands you used in the exact order
> you used them, plus grass version and operating system (wasn't it 3.0 on
> Linux?).
>
> Markus M
>
>> any ideas,
>>
>> Stephen
>>
>>
>> On Thu, Jul 9, 2009 at 1:50 PM, Markus
>> Metz<markus.metz.giswork at googlemail.com> wrote:
>>
>>> stephen sefick wrote:
>>>
>>>> I followed the directions all set to srtm, computation region set to
>>>> resolution of the coarsest (they are all the same and 00:00:01).  The
>>>> map is still coming out as 7 different solid color blocks.
>>>>
>>>>
>>> You have set the region to include all tiles? You have zoomed to the
>>> current region? The patched DEM still ranges from 0-296 only and not
>>> from 9-800 (r.info -r)?
>>>
>>> I've done that regularly with SRTM tiles and it worked, no problems
>>> (6.4.0RC5).
>>>
>>>> On Thu, Jul 9, 2009 at 12:58 PM, Markus
>>>> Metz<markus.metz.giswork at googlemail.com> wrote:
>>>>
>>>>
>>>>> stephen sefick wrote:
>>>>>
>>>>>
>>>>>> values range from ~-9 to ~800 there is a tile which has no elevation.
>>>>>> The patched dem only ranges from 0-296.  This may be the problem.
>>>>>>
>>>>>>
>>>>>>
>>>>> It seems that the current computational region did not include all tiles.
>>>>> Try setting the computational region to include all tiles with g.region
>>>>> rast=<all your tiles>.
>>>>> Check the resolution of each tile with r.info -s. If they are not all
>>>>> the same, use the coarsest resolution to be safe.
>>>>> Check the resolution of the computational region. It must be the same
>>>>> like the coarsest resolution, if not, set it to that.
>>>>> Set the same color rules for all tiles. Use srtm or etopo2 but not
>>>>> elevation because elevation will be different for each tile.
>>>>> Display all tiles, zoom to the computational region.
>>>>> Patch all tiles.
>>>>> Set the same color rules to the patched DEM like to the tiles.
>>>>> Add the patched DEM to the display, it should look like the previous
>>>>> display with all the tiles.
>>>>>
>>>>> Good luck,
>>>>>
>>>>> Markus M
>>>>>
>>>>>
>>>>>
>>>>>
>>>>
>>>>
>>>>
>>>
>>
>>
>>
>>
>
>



-- 
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