[GRASS-user] How to remove small closed lines

GRASS GRASS user
1

Hi, maybe you can identify your closed lines with v.to.db command and the coordinate of the start point and the end point

v.to.db map=mylines option=end type=line col=coordEnd
v.to.db map=mylines option=start type=line col=coordStart

and tests if the coordinates of the startNode and the EndNode are equals, the line is closed and you can tag your lines .
And use after the v.extract command to extract only the lines which are not closed.

Hope it can be helpful

Michael

Le 06/11/2013 16:25, grass-user-request@lists.osgeo.org a écrit :

Date: Wed, 6 Nov 2013 12:59:29 +0000
From: BLANDENIER Lucien<lucien.blandenier@unine.ch>
To:"grass-user@lists.osgeo.org" <grass-user@lists.osgeo.org>
Subject: [GRASS-user] How to remove small closed lines
Message-ID:
  <84F1DDBD03D55944AA4E63A2FE5EADE5530AB5EB@MAIL-MBX-05.UNINE.CH>
Content-Type: text/plain; charset="iso-8859-1"

Hi,

I would like to know how to remove automatically small circles (closed lines, not area). I've tried with v.clean and v.generalize but I just get to remove line which are not closed.

Regards

Lucien

--
Signature electronique
INRA <http://www.inra.fr>
*Michael Rabotin*
*Ingénieur d'Etude SIG / GIS Engineer*
michael.rabotin@supagro.inra.fr <mailto:#>
*UMR LISAH - Centre de Montpellier*
Tèl. : +33 (0)4 99 61 23 85
Mobile : +33 (0)6 76 45 46 83
Fax : +33 (0)4 67 63 26 14

Bat 24 - 2 place Pierre Viala
34060 Montpellier cedex 2
France
www.inra.fr <http://www.inra.fr> www.openfluid-project.org <http://www.openfluid-project.org>

(attachments)

logo-INRA2012.gif

2

In fact I need to remove some of the closed line according to their length.

Normally v.clean is able to remove small line with a threshold but it is not working for closed lines... I was wondering if there is an easy way to do this. Or maybe is there a possibility to cut the "closed" lines

regards

________________________________
De : Rabotin Michael [rabotin@supagro.inra.fr]
Envoyé : mercredi 6 novembre 2013 16:54
À : grass-user@lists.osgeo.org
Cc : BLANDENIER Lucien
Objet : Re: [GRASS-user] How to remove small closed lines

Hi, maybe you can identify your closed lines with v.to.db command and the coordinate of the start point and the end point

v.to.db map=mylines option=end type=line col=coordEnd
v.to.db map=mylines option=start type=line col=coordStart

and tests if the coordinates of the startNode and the EndNode are equals, the line is closed and you can tag your lines .
And use after the v.extract command to extract only the lines which are not closed.

Hope it can be helpful

Michael

Le 06/11/2013 16:25, grass-user-request@lists.osgeo.org<mailto:grass-user-request@lists.osgeo.org> a écrit :

Date: Wed, 6 Nov 2013 12:59:29 +0000
From: BLANDENIER Lucien <lucien.blandenier@unine.ch><mailto:lucien.blandenier@unine.ch>
To: "grass-user@lists.osgeo.org"<mailto:grass-user@lists.osgeo.org> <grass-user@lists.osgeo.org><mailto:grass-user@lists.osgeo.org>
Subject: [GRASS-user] How to remove small closed lines
Message-ID:
        <84F1DDBD03D55944AA4E63A2FE5EADE5530AB5EB@MAIL-MBX-05.UNINE.CH><mailto:84F1DDBD03D55944AA4E63A2FE5EADE5530AB5EB@MAIL-MBX-05.UNINE.CH>
Content-Type: text/plain; charset="iso-8859-1"

Hi,

I would like to know how to remove automatically small circles (closed lines, not area). I've tried with v.clean and v.generalize but I just get to remove line which are not closed.

Regards

Lucien

--
[INRA]<http://www.inra.fr>

Michael Rabotin
Ingénieur d'Etude SIG / GIS Engineer
michael.rabotin@supagro.inra.fr<mailto:#>
UMR LISAH - Centre de Montpellier
Tèl. : +33 (0)4 99 61 23 85
Mobile : +33 (0)6 76 45 46 83
Fax : +33 (0)4 67 63 26 14

Bat 24 - 2 place Pierre Viala
34060 Montpellier cedex 2
France
www.inra.fr<http://www.inra.fr> www.openfluid-project.org<http://www.openfluid-project.org>

(attachments)

logo-INRA2012.gif

3

So when you have identified in your lines map which lines are closed or not (with the coordinates equality), you can compute the length of all the lines and remove the closed ones which are under the threshold you want with v.extract. You can have two columns in your line map, one which identify if the line is closed or not and one whith the length. And you can used the v.extract command with where="coltag="closed" AND collength<xxx"

Mick

Le 06/11/2013 17:23, BLANDENIER Lucien a écrit :

In fact I need to remove some of the closed line according to their length.

Normally v.clean is able to remove small line with a threshold but it is not working for closed lines... I was wondering if there is an easy way to do this. Or maybe is there a possibility to cut the "closed" lines

regards

________________________________
De : Rabotin Michael [rabotin@supagro.inra.fr]
Envoyé : mercredi 6 novembre 2013 16:54
À : grass-user@lists.osgeo.org
Cc : BLANDENIER Lucien
Objet : Re: [GRASS-user] How to remove small closed lines

Hi, maybe you can identify your closed lines with v.to.db command and the coordinate of the start point and the end point

v.to.db map=mylines option=end type=line col=coordEnd
v.to.db map=mylines option=start type=line col=coordStart

and tests if the coordinates of the startNode and the EndNode are equals, the line is closed and you can tag your lines .
And use after the v.extract command to extract only the lines which are not closed.

Hope it can be helpful

Michael

Le 06/11/2013 16:25, grass-user-request@lists.osgeo.org<mailto:grass-user-request@lists.osgeo.org> a écrit :

Date: Wed, 6 Nov 2013 12:59:29 +0000
From: BLANDENIER Lucien <lucien.blandenier@unine.ch><mailto:lucien.blandenier@unine.ch>
To: "grass-user@lists.osgeo.org"<mailto:grass-user@lists.osgeo.org> <grass-user@lists.osgeo.org><mailto:grass-user@lists.osgeo.org>
Subject: [GRASS-user] How to remove small closed lines
Message-ID:
         <84F1DDBD03D55944AA4E63A2FE5EADE5530AB5EB@MAIL-MBX-05.UNINE.CH><mailto:84F1DDBD03D55944AA4E63A2FE5EADE5530AB5EB@MAIL-MBX-05.UNINE.CH>
Content-Type: text/plain; charset="iso-8859-1"

Hi,

I would like to know how to remove automatically small circles (closed lines, not area). I've tried with v.clean and v.generalize but I just get to remove line which are not closed.

Regards

Lucien

--
[INRA]<http://www.inra.fr>

Michael Rabotin
Ingénieur d'Etude SIG / GIS Engineer
michael.rabotin@supagro.inra.fr<mailto:#>
UMR LISAH - Centre de Montpellier
Tèl. : +33 (0)4 99 61 23 85
Mobile : +33 (0)6 76 45 46 83
Fax : +33 (0)4 67 63 26 14

Bat 24 - 2 place Pierre Viala
34060 Montpellier cedex 2
France
www.inra.fr<http://www.inra.fr> www.openfluid-project.org<http://www.openfluid-project.org>

--
Signature electronique
INRA <http://www.inra.fr>
*Michael Rabotin*
*Ingénieur d'Etude SIG / GIS Engineer*
michael.rabotin@supagro.inra.fr <mailto:#>
*UMR LISAH - Centre de Montpellier*
Tèl. : +33 (0)4 99 61 23 85
Mobile : +33 (0)6 76 45 46 83
Fax : +33 (0)4 67 63 26 14

Bat 24 - 2 place Pierre Viala
34060 Montpellier cedex 2
France
www.inra.fr <http://www.inra.fr> www.openfluid-project.org <http://www.openfluid-project.org>

(attachments)

logo-INRA2012.gif