Re: [GRASS-user] using v.line.center
Dzie,kuje bardzo Maciej, It has worked, 2008/6/6 Maciej Sieczka [EMAIL PROTECTED]: Manuel Sangiao pisze: Hi all, after the reprojection in another mapset I used v.line.center, all ok. But, I obtain a new layer without database. The input layer have database. v.line.center does not copy the input vector's table to output vector. v.db.connect -p glines1 Vector map glines1 is connected by: layer 2 table glines1 in database /scratch/manuel/GISDATA//admprojected/manuel/dbf/ through driver dbf with key cat I have read that the result layer (pts1) contains the category numbers of the input vector line layer. Is there a solution? Yes. As the category numbers are the same, you can: # given that the name of the v.line.center's input vector is lines and # the output is points: # copy the input table: db.copy from_table=lines to_table=points # connect the table points to vector map points: v.db.connect points table=points Now query (d.what.vect, v.db.select) to check if everything's OK. Mind that I assume plenty of defaults in the example above - verify your layer number, key column name etc. Refer to to commands's manuals. Maciek -- Maciej Sieczka www.sieczka.org ___ grass-user mailing list grass-user@lists.osgeo.org http://lists.osgeo.org/mailman/listinfo/grass-user
Re: [GRASS-user] using v.line.center
Markus Neteler pisze: On Thu, Jun 5, 2008 at 7:38 PM, Maciej Sieczka [EMAIL PROTECTED] wrote: Manuel Sangiao pisze: WARNING: Cannot get point on line: cat=927 offset=89379.795093 (line lenght=2.219076) P 927 927 89379.795093 I guess the reason for this error is the projection (mapset?) unit. The projection unit(s) in my mapset is degree(s). And the length units are meters. v.line.center as it is can't work in latlon Location. It uses v.to.db for length calculation, which cannot measure in degrees, I think it can... from the man page: When calculating perimeters in Latitude-Longitude locations, the geodesic distance between the vertices is used. Markus v.line.center uses v.to.db to calculate lengths of input vector lines, which then are fed into v.segment as offsets to create lines' center points. v.segment expects offsets in units of the Location. If these are degrees we have a problem because v.to.db can't calculate length in degrees. It supports the following units: mi,miles,f,feet,me,meters,k,kilometers,a,acres,h,hectares Therefore, v.line center can't work in latlon locations. -- Maciej Sieczka www.sieczka.org ___ grass-user mailing list grass-user@lists.osgeo.org http://lists.osgeo.org/mailman/listinfo/grass-user
Re: [GRASS-user] using v.line.center
Thanks Hamish for your help, that was helpful. But now, when I use *v.line.center,* I get the following error: WARNING: Cannot get point on line: cat=927 offset=89379.795093 (line lenght=2.219076) P 927 927 89379.795093 I guess the reason for this error is the projection (mapset?) unit. The projection unit(s) in my mapset is degree(s). And the length units are meters. So, how can i change the mapset units. Should I create another mapset with the properly units? regards Manuel 2008/6/5, Hamish [EMAIL PROTECTED]: Manuel Sangiao wrote: in order to use *v.line.center* properly I use* v.category* to adjust category assignment. As a result I get: GRASS 6.2.2 (admeurop): v.category in=bound1 layer=2 out=boundary1 --o Number of lines : 0 Number of boundaries: 592 Then I use *v.line.center* to get the middle points of the boundaries (That's right?). Then I get the following result: 0 records updated/inserted So, I get nothing Any can me help? I don't understand this result. use v.type to convert boundaries to lines first. Hamish ___ grass-user mailing list grass-user@lists.osgeo.org http://lists.osgeo.org/mailman/listinfo/grass-user
Re: [GRASS-user] using v.line.center
Manuel Sangiao pisze: WARNING: Cannot get point on line: cat=927 offset=89379.795093 (line lenght=2.219076) P 927 927 89379.795093 I guess the reason for this error is the projection (mapset?) unit. The projection unit(s) in my mapset is degree(s). And the length units are meters. v.line.center as it is can't work in latlon Location. It uses v.to.db for length calculation, which cannot measure in degrees, and then pipes the result to v.segment, which assumes Location unit - if it's degree the script won't work. It would be cool if v.segment could accept offsets in various units. I should fix v.line.center to check location units, and update the manual. Someday. So, how can i change the mapset units. Should I create another mapset with the properly units? Reproject the data into a metric location. -- Maciej Sieczka www.sieczka.org ___ grass-user mailing list grass-user@lists.osgeo.org http://lists.osgeo.org/mailman/listinfo/grass-user
[GRASS-user] using v.line.center
Hi list, in order to use *v.line.center* properly I use* v.category* to adjust category assignment. As a result I get: GRASS 6.2.2 (admeurop): v.category in=bound1 layer=2 out=boundary1 --o WARNING: The vector 'boundary1' already exists and will be overwritten. 116 new centroids placed in output map Building topology ... 711 primitives registered Building areas: 100% 119 areas built 28 isles built Attaching islands: 100% Attaching centroids: 100% Topology was built. Number of nodes : 631 Number of primitives: 711 Number of points : 0 Number of lines : 0 Number of boundaries: 592 Number of centroids : 119 Number of areas : 119 Number of isles : 28 Number of incorrect boundaries : 299 -- Then I use *v.line.center* to get the middle points of the boundaries (That's right?). Then I get the following result: GRASS 6.2.2 (admeurop):/scratch/manuel/GISDATA/scripts v.line.center in=boundary1 out=points1 --o 0 categories read from map 0 records selected from table 0 categories read from map exist in selection from table 0 categories read from map don't exist in selection from table 0 records updated/inserted 0 update/insert errors WARNING: The vector 'points1' already exists and will be overwritten. Building topology ... 0 primitives registered 0 areas built 0 isles built Attaching islands: Attaching centroids: Topology was built. Number of nodes : 0 Number of primitives: 0 Number of points : 0 Number of lines : 0 Number of boundaries: 0 Number of centroids : 0 Number of areas : 0 Number of isles : 0 Done. -- So, I get nothing Any can me help? I don't understand this result. cheers Manuel ___ grass-user mailing list grass-user@lists.osgeo.org http://lists.osgeo.org/mailman/listinfo/grass-user
Re: [GRASS-user] using v.line.center
Manuel Sangiao wrote: in order to use *v.line.center* properly I use* v.category* to adjust category assignment. As a result I get: GRASS 6.2.2 (admeurop): v.category in=bound1 layer=2 out=boundary1 --o Number of lines : 0 Number of boundaries: 592 Then I use *v.line.center* to get the middle points of the boundaries (That's right?). Then I get the following result: 0 records updated/inserted So, I get nothing Any can me help? I don't understand this result. use v.type to convert boundaries to lines first. Hamish ___ grass-user mailing list grass-user@lists.osgeo.org http://lists.osgeo.org/mailman/listinfo/grass-user
