Re: [Qgis-user] finding the radius of a curve
Hi again,
On that matter: If you can isolate only the arc-part of your geometry,
you could that circular arc into the Postgis-function
"ST_MinimumBoundingRadius()" to detect center-point and radius. See
http://www.postgis.net/docs/manual-2.5/ST_MinimumBoundingRadius.html -
maybe worth a try?
Sample query:
SELECT ST_AsText(center), radius
FROM ST_MinimumBoundingRadius('CIRCULARSTRING(220268 150415,220227
150505,220227 150406)');
RESULT:
"POINT(220237.62195122 150455.5)" "50.6268293270462"
Greetings,
Andreas
Am 29.04.19 um 18:21 schrieb Cory Albrecht:
I tried saving a few layers that had arcs and circles (x,y, r coords),
but QGIS converts each curve to a bunch of straight line segments
instead of saving them as curves. :-(
On Mon, Apr 22, 2019 at 3:33 AM McDonaldR <mailto:mcdona...@angus.gov.uk>> wrote:
As your data is in PostGIS and assuming that they are arcs (curved
lines part of a circle) you could use some geometry and spatial
SQL functions to calculate the radius of any curve knowing the
coordinates of the end points of the curve.
To quote the pseudo code on the linked page:
“To calculate the radius of an arc, take the height -- "H" -- of
the arc and divide it by two. Call the result "C." Now take the
width -- "W" -- of the arc and square it by multiplying it by
itself. Call the result "D." Next multiply height, "H," by eight
and call this result "E." Divide "D" by "E" and call the result
"F." The radius of the arc is C plus F.”
https://sciencing.com/calculate-radius-curve-7804090.html
Could probably be wrapped in a function and run against any curve.
Ross
*From:*Qgis-user [mailto:qgis-user-boun...@lists.osgeo.org
<mailto:qgis-user-boun...@lists.osgeo.org>] *On Behalf Of *Cory
Albrecht
*Sent:* 19 April 2019 17:08
*To:* qgis-user@lists.osgeo.org <mailto:qgis-user@lists.osgeo.org>
*Subject:* Re: [Qgis-user] finding the radius of a curve
I'll give it a try. Thanks!
On Sun, Apr 14, 2019 at 7:52 AM Mike Flannigan mailto:mikef...@att.net>> wrote:
Draw a circle and measure the diameter/radius.
Maybe use this plugin to create a circle:
https://plugins.qgis.org/plugins/CADDigitize/
Mike
On 4/13/2019 2:00 PM, qgis-user-requ...@lists.osgeo.org
<mailto:qgis-user-requ...@lists.osgeo.org> wrote:
> Hello all,
>
> I'm looking for a way to find the radius of a curve (for
roads, railyways)
> in QGIS. If it were a paper map I could do it with a
drafting compass
> (calipers to some) and a ruler, but this is a PostGIS layer.
>
> Any plugin recommendations or links to a set of steps to
accomplish this?
> Thanks in advance!
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Re: [Qgis-user] finding the radius of a curve
Hi Cory, Not if you use a file-format that supports arcs: Geopackage, Postgis, Interlines, GML. Maybe also FGDB (but not sure if OGR supports curves for that format). Greetings, Andreas Am 29.04.19 um 18:21 schrieb Cory Albrecht: I tried saving a few layers that had arcs and circles (x,y, r coords), but QGIS converts each curve to a bunch of straight line segments instead of saving them as curves. :-( On Mon, Apr 22, 2019 at 3:33 AM McDonaldR <mailto:mcdona...@angus.gov.uk>> wrote: As your data is in PostGIS and assuming that they are arcs (curved lines part of a circle) you could use some geometry and spatial SQL functions to calculate the radius of any curve knowing the coordinates of the end points of the curve. To quote the pseudo code on the linked page: “To calculate the radius of an arc, take the height -- "H" -- of the arc and divide it by two. Call the result "C." Now take the width -- "W" -- of the arc and square it by multiplying it by itself. Call the result "D." Next multiply height, "H," by eight and call this result "E." Divide "D" by "E" and call the result "F." The radius of the arc is C plus F.” https://sciencing.com/calculate-radius-curve-7804090.html Could probably be wrapped in a function and run against any curve. Ross *From:*Qgis-user [mailto:qgis-user-boun...@lists.osgeo.org <mailto:qgis-user-boun...@lists.osgeo.org>] *On Behalf Of *Cory Albrecht *Sent:* 19 April 2019 17:08 *To:* qgis-user@lists.osgeo.org <mailto:qgis-user@lists.osgeo.org> *Subject:* Re: [Qgis-user] finding the radius of a curve I'll give it a try. Thanks! On Sun, Apr 14, 2019 at 7:52 AM Mike Flannigan mailto:mikef...@att.net>> wrote: Draw a circle and measure the diameter/radius. Maybe use this plugin to create a circle: https://plugins.qgis.org/plugins/CADDigitize/ Mike On 4/13/2019 2:00 PM, qgis-user-requ...@lists.osgeo.org <mailto:qgis-user-requ...@lists.osgeo.org> wrote: > Hello all, > > I'm looking for a way to find the radius of a curve (for roads, railyways) > in QGIS. If it were a paper map I could do it with a drafting compass > (calipers to some) and a ruler, but this is a PostGIS layer. > > Any plugin recommendations or links to a set of steps to accomplish this? > Thanks in advance! This message is strictly confidential. If you have received this in error, please inform the sender and remove it from your system. If received in error you may not copy, print, forward or use it or any attachment in any way. This message is not capable of creating a legal contract or a binding representation and does not represent the views of Angus Council. Emails may be monitored for security and network management reasons.Messages containing inappropriate content may be intercepted. Angus Council does not accept any liability for any harm that may be caused to the recipient system or data on it by this message or any attachment. ___ Qgis-user mailing list Qgis-user@lists.osgeo.org List info: https://lists.osgeo.org/mailman/listinfo/qgis-user Unsubscribe: https://lists.osgeo.org/mailman/listinfo/qgis-user ___ Qgis-user mailing list Qgis-user@lists.osgeo.org List info: https://lists.osgeo.org/mailman/listinfo/qgis-user Unsubscribe: https://lists.osgeo.org/mailman/listinfo/qgis-user
Re: [Qgis-user] finding the radius of a curve
I tried saving a few layers that had arcs and circles (x,y, r coords), but QGIS converts each curve to a bunch of straight line segments instead of saving them as curves. :-( On Mon, Apr 22, 2019 at 3:33 AM McDonaldR wrote: > As your data is in PostGIS and assuming that they are arcs (curved lines > part of a circle) you could use some geometry and spatial SQL functions to > calculate the radius of any curve knowing the coordinates of the end points > of the curve. > > > > To quote the pseudo code on the linked page: > > > > “To calculate the radius of an arc, take the height -- "H" -- of the arc > and divide it by two. Call the result "C." Now take the width -- "W" -- of > the arc and square it by multiplying it by itself. Call the result "D." > Next multiply height, "H," by eight and call this result "E." Divide "D" by > "E" and call the result "F." The radius of the arc is C plus F.” > > > > https://sciencing.com/calculate-radius-curve-7804090.html > > > > Could probably be wrapped in a function and run against any curve. > > > > Ross > > > > *From:* Qgis-user [mailto:qgis-user-boun...@lists.osgeo.org] *On Behalf > Of *Cory Albrecht > *Sent:* 19 April 2019 17:08 > *To:* qgis-user@lists.osgeo.org > *Subject:* Re: [Qgis-user] finding the radius of a curve > > > > I'll give it a try. Thanks! > > > > On Sun, Apr 14, 2019 at 7:52 AM Mike Flannigan wrote: > > > Draw a circle and measure the diameter/radius. > > Maybe use this plugin to create a circle: > https://plugins.qgis.org/plugins/CADDigitize/ > > > Mike > > > On 4/13/2019 2:00 PM, qgis-user-requ...@lists.osgeo.org wrote: > > Hello all, > > > > I'm looking for a way to find the radius of a curve (for roads, > railyways) > > in QGIS. If it were a paper map I could do it with a drafting compass > > (calipers to some) and a ruler, but this is a PostGIS layer. > > > > Any plugin recommendations or links to a set of steps to accomplish this? > > Thanks in advance! > > > > This message is strictly confidential. If you have received this in error, > please inform the sender and remove it from your system. If received in > error you may not copy, print, forward or use it or any attachment in any > way. This message is not capable of creating a legal contract or a binding > representation and does not represent the views of Angus Council. Emails > may be monitored for security and network management reasons. Messages > containing inappropriate content may be intercepted. Angus Council does not > accept any liability for any harm that may be caused to the recipient > system or data on it by this message or any attachment. > ___ Qgis-user mailing list Qgis-user@lists.osgeo.org List info: https://lists.osgeo.org/mailman/listinfo/qgis-user Unsubscribe: https://lists.osgeo.org/mailman/listinfo/qgis-user
Re: [Qgis-user] finding the radius of a curve
As your data is in PostGIS and assuming that they are arcs (curved lines part of a circle) you could use some geometry and spatial SQL functions to calculate the radius of any curve knowing the coordinates of the end points of the curve. To quote the pseudo code on the linked page: “To calculate the radius of an arc, take the height -- "H" -- of the arc and divide it by two. Call the result "C." Now take the width -- "W" -- of the arc and square it by multiplying it by itself. Call the result "D." Next multiply height, "H," by eight and call this result "E." Divide "D" by "E" and call the result "F." The radius of the arc is C plus F.” https://sciencing.com/calculate-radius-curve-7804090.html Could probably be wrapped in a function and run against any curve. Ross From: Qgis-user [mailto:qgis-user-boun...@lists.osgeo.org] On Behalf Of Cory Albrecht Sent: 19 April 2019 17:08 To: qgis-user@lists.osgeo.org Subject: Re: [Qgis-user] finding the radius of a curve I'll give it a try. Thanks! On Sun, Apr 14, 2019 at 7:52 AM Mike Flannigan mailto:mikef...@att.net>> wrote: Draw a circle and measure the diameter/radius. Maybe use this plugin to create a circle: https://plugins.qgis.org/plugins/CADDigitize/ Mike On 4/13/2019 2:00 PM, qgis-user-requ...@lists.osgeo.org<mailto:qgis-user-requ...@lists.osgeo.org> wrote: > Hello all, > > I'm looking for a way to find the radius of a curve (for roads, railyways) > in QGIS. If it were a paper map I could do it with a drafting compass > (calipers to some) and a ruler, but this is a PostGIS layer. > > Any plugin recommendations or links to a set of steps to accomplish this? > Thanks in advance! This message is strictly confidential. If you have received this in error, please inform the sender and remove it from your system. If received in error you may not copy, print, forward or use it or any attachment in any way. This message is not capable of creating a legal contract or a binding representation and does not represent the views of Angus Council. Emails may be monitored for security and network management reasons. Messages containing inappropriate content may be intercepted. Angus Council does not accept any liability for any harm that may be caused to the recipient system or data on it by this message or any attachment. ___ Qgis-user mailing list Qgis-user@lists.osgeo.org List info: https://lists.osgeo.org/mailman/listinfo/qgis-user Unsubscribe: https://lists.osgeo.org/mailman/listinfo/qgis-user
Re: [Qgis-user] finding the radius of a curve
I'll give it a try. Thanks! On Sun, Apr 14, 2019 at 7:52 AM Mike Flannigan wrote: > > Draw a circle and measure the diameter/radius. > > Maybe use this plugin to create a circle: > https://plugins.qgis.org/plugins/CADDigitize/ > > > Mike > > > On 4/13/2019 2:00 PM, qgis-user-requ...@lists.osgeo.org wrote: > > Hello all, > > > > I'm looking for a way to find the radius of a curve (for roads, > railyways) > > in QGIS. If it were a paper map I could do it with a drafting compass > > (calipers to some) and a ruler, but this is a PostGIS layer. > > > > Any plugin recommendations or links to a set of steps to accomplish this? > > Thanks in advance! > > ___ Qgis-user mailing list Qgis-user@lists.osgeo.org List info: https://lists.osgeo.org/mailman/listinfo/qgis-user Unsubscribe: https://lists.osgeo.org/mailman/listinfo/qgis-user
Re: [Qgis-user] finding the radius of a curve
Draw a circle and measure the diameter/radius. Maybe use this plugin to create a circle: https://plugins.qgis.org/plugins/CADDigitize/ Mike On 4/13/2019 2:00 PM, qgis-user-requ...@lists.osgeo.org wrote: Hello all, I'm looking for a way to find the radius of a curve (for roads, railyways) in QGIS. If it were a paper map I could do it with a drafting compass (calipers to some) and a ruler, but this is a PostGIS layer. Any plugin recommendations or links to a set of steps to accomplish this? Thanks in advance! ___ Qgis-user mailing list Qgis-user@lists.osgeo.org List info: https://lists.osgeo.org/mailman/listinfo/qgis-user Unsubscribe: https://lists.osgeo.org/mailman/listinfo/qgis-user
[Qgis-user] finding the radius of a curve
Hello all, I'm looking for a way to find the radius of a curve (for roads, railyways) in QGIS. If it were a paper map I could do it with a drafting compass (calipers to some) and a ruler, but this is a PostGIS layer. Any plugin recommendations or links to a set of steps to accomplish this? Thanks in advance! ___ Qgis-user mailing list Qgis-user@lists.osgeo.org List info: https://lists.osgeo.org/mailman/listinfo/qgis-user Unsubscribe: https://lists.osgeo.org/mailman/listinfo/qgis-user
