All,
I am thinking of moving to grass7. I know that the vector back end has changed and there is a requirement to rebuild vector topology. Once this is done can grass6 still read the vectors with little error? I would like to keep grass 6 around to make sure that, if I need to, I can use the "old stand by" if I can not figure out how to do it in grass 7. Many thanks for all of the help.
kind regards,
--
Stephen Sefick
**************************************************
Auburn University
Biological Sciences
331 Funchess Hall
Auburn, Alabama
36849
**************************************************
sas0025@auburn.edu
http://www.auburn.edu/~sas0025
**************************************************
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
"A big computer, a complex algorithm and a long time does not equal science."
-Robert Gentleman
On Friday 15 of March 2013 09:31:06 Stephen Sefick wrote:
All,
I am thinking of moving to grass7. I know that the vector back end has
changed and there is a requirement to rebuild vector topology.
Better & Faster (thanks to all and especially to Markus Metz) 
Once this is done can grass6 still read the vectors with little error?
As far as I can tell, you only need to re-build the topology (if you switch
from G6 to G7 and vice versa).
I would like to keep grass 6 around to make sure that, if I need to, I can
use the "old stand by" if I can not figure out how to do it in grass 7.
Me too -- still have G6 aside for working although I do most of the stuff in
G7.
Greets, Nikos
On Fri, Mar 15, 2013 at 3:31 PM, Stephen Sefick <sas0025@auburn.edu> wrote:
All,
I am thinking of moving to grass7. I know that the vector back end has
changed and there is a requirement to rebuild vector topology. Once this is
done can grass6 still read the vectors with little error?
No, you have to rebuilt the topology there.
But that's easily done with v.build or v.build.all.
I would like to
keep grass 6 around to make sure that, if I need to, I can use the "old
stand by" if I can not figure out how to do it in grass 7.
You can - see:
http://grasswiki.osgeo.org/wiki/Convert_all_GRASS_6_vector_maps_to_GRASS_7
Markus
On Friday 15 of March 2013 17:02:01 Nikos Alexandris wrote:
On Friday 15 of March 2013 09:31:06 Stephen Sefick wrote:
> All,
> I am thinking of moving to grass7. I know that the vector back end has
> changed and there is a requirement to rebuild vector topology.
Better & Faster (thanks to all and especially to Markus Metz)
On the matter, I just imported the following data set:
402K BurntAreas_2000_2012.dbf
367 BurntAreas_2000_2012.prj
7.9M BurntAreas_2000_2012.shp
115K BurntAreas_2000_2012.shx
# both cases, identical report on overlapping areas:
--%<---
WARNING: 11018 areas represent more (overlapping) features, because
polygons overlap in input layer(s). Such areas are linked to more
than 1 row in attribute table. The number of features for those
areas is stored as category in layer 2
-----------------------------------------------------
14685 input polygons
Total area: 4.78085E+10 (34287 areas)
Overlapping area: 4.05856E+09 (11018 areas)
Area without category: 9.32859E+08 (3744 areas)
--->%--
in G6, revision=55280M
real 2m4.002s
user 1m19.377s
sys 0m9.093s
# v.info -t returns
nodes=63241
points=0
lines=0
boundaries=57140
centroids=30543
areas=34287
islands=9845
faces=0
kernels=0
primitives=87683
map3d=0
in G7, revision=55284M
real 0m33.384s
user 0m29.194s
sys 0m4.092s
# v.info -t returns
nodes=32698
points=0
lines=0
boundaries=57140
centroids=30543
areas=34287
islands=9845
primitives=87683
map3d=0
Much faster!!
Thanks, Nikos
--
ps- Curious: why is the reported number of "nodes" different?
On Mon, Mar 18, 2013 at 1:21 PM, Nikos Alexandris
<nik@nikosalexandris.net> wrote:
in G6, revision=55280M
real 2m4.002s
user 1m19.377s
sys 0m9.093s
# v.info -t returns
nodes=63241
[snip]
in G7, revision=55284M
real 0m33.384s
user 0m29.194s
sys 0m4.092s
# v.info -t returns
nodes=32698
[snip]
ps- Curious: why is the reported number of "nodes" different?
In G7, points and centroids no longer have nodes. Nodes are only used
to connect lines/boundaries (G6 + G7).
Markus M
nik@nikosalexandris.net:
> in G6, revision=55280M
> real 2m4.002s
> user 1m19.377s
> sys 0m9.093s
> # v.info -t returns
> nodes=63241
[snip]
> in G7, revision=55284M
> real 0m33.384s
> user 0m29.194s
> sys 0m4.092s
> # v.info -t returns
> nodes=32698
[snip]
> ps- Curious: why is the reported number of "nodes" different?
Markus Metz:
In G7, points and centroids no longer have nodes. Nodes are only used
to connect lines/boundaries (G6 + G7).
Thanks for the quick-feedback.
Nikos