Hi Micha and Markus,
On 2019-06-18 at 10:07 -04, Micha Silver <[email protected]> wrote...
> Do you really want a vector polygon map with > 2 billion features?
No, and there are not that many.
% r.info -r basins
min=-2147474681
max=2147429730
But I don't have categories from 1 to 2147429730. The values are sparse. I
describe my workflow and why I've created these sparse values in more detail
below.
Even though << 2 billion, there should be many basins. This is all of Greenland
at 30 m resolution, which is 4.5 billion features.
Taking a step back, I'm trying to generate unique basin values that match the
stream and outlet CAT values. Here is my workflow which doesn't appear to have
any problems when run at 90x90 m resolution (400 million cells) but fails at
30x30 m resolution (10x as many, or 4.5 billion cells).
1) Find streams:
r.stream.extract elevation=head threshold=${THRESH} memory=16384 direction=dir
stream_raster=streams stream_vector=streams
2) Find outlets. Where streams have outlets, use the same CAT value so the two
can be linked in further analysis. But many outlets don't have streams. These
need to have unique categories for the next step when we find basins. This is
where my error is. I set the unique value to the cell #, which is > 2 billion
when using a 30x30 m domain.
r.mapcalc "outlets_all = if(dir < 0, 1, null())"
r.mapcalc "outlets_streams_1 = if((dir < 0) && (not(isnull(streams))), streams,
outlets_all)"
### BUG INTRODUCED HERE, setting (eventual) cat to cell number:
r.mapcalc "outlets_streams = if(outlets_streams_1 != 1, outlets_streams_1,
max(outlets_streams_1)+1+col()+(max(col())*(row()-1)))"
# convert outlets to a vector.
r.out.xyz input=outlets_streams | \
v.in.ascii input=- output=outlets_streams separator=pipe \
columns="x int, y int, cat int" x=1 y=2 cat=3
Q: How can I create the outlets_streams vector for all locations where dir < 0
(all outlets), that maintains the same value as the streams raster where that
raster is defined, but unique values at all other locations where streams is
not defined, but dir < 0?
3) Find basins
r.stream.basins -m direction=dir points=outlets_streams basins=basins_all
memory=16384 --verbose
4) Absorb small basins
r.clump -d input=basins_all output=basins_nosmall minsize=124
r.mode base=basins_nosmall cover=basins_all output=basins
### BUG APPEARS HERE
r.to.vect -v input=basins output=basins type=area
# drop outlets for absorbed basins.
r.mapcalc "outlets = if(outlets_streams == basins, basins, null())"
r.to.vect -v input=outlets output=outlets type=point
NOTE: I use r.mode instead of r.area because I need to maintain the category
value, so that eventual vectors can have linked primary keys. r.area re-assigns
categories.
Any advice how to generate streams, outlets, and basins all with linked primary
key would be much appreciated.
Thanks,
-k.
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