[Qgis-user] Re: Azimuth and Distance Plugin (was Re: your old qgis plugins)
Fred LaPlante
flaplante at flos-inc.com
Wed May 18 10:33:43 PDT 2011
OK, looks like we are both talking about the same 'English' system of
metes & bounds. Your parcel looks just like mine. And none of the
bearings look nearly precise enough to guarantee closure. The most
conspicuous absence is lack of a True vs magnetic notation. For Canada
that can be a killer - and magnetic can easily vary 40min in ten years.
Also I see that the surveyor didn't enter the bearings in a consistent
way as he walked around the property so the bearings have to be reversed
manually, or a negative sign used.
Anyway, I'll get a copy of qGis running and see what I can do with your
drawing.
Fred
On 5/18/2011 1:19 PM, Darren Cope wrote:
> Thanks Fred,
>
> I've (re)attached the image example--the coordinates we deal with in
> Ontario (and most of Canada) seem to (almost all) come in the format
> shown in my attachment. It doesn't make a whole lot of sense to me
> from a 'usability' standpoint, but...
>
> Darren Cope
> http://darrencope.com
> http://dmcope.freeshell.org
>
>
> 2011/5/18 Fred LaPlante <flaplante at flos-inc.com
> <mailto:flaplante at flos-inc.com>>
>
> Wow! voices from the past.
>
> Darren,
>
> I haven't done anything with qGIS for over a year now. But this
> does remind me I need to get back to it again just to catch up on
> some things here on my desk. Unfortunately I 'upgraded?' my
> computer system to Windows7 since then and qGIS didn't make the
> transfer (though the data did make it!). So I will have to answer
> your questions from memory.
>
> I think Mauricio got it all right. Here in Maine, USA, land
> boundaries in property deeds and maps are given in 'metes and
> bounds' that is nnn.nn feet North/South xxdeg East or West. (For
> example 950.5 feet N 30deg 45Min 20Sec East). So what I would do
> is to establish a starting point from whatever corner I could pin
> down on a map and then 'walk' around the property entering the
> distance and heading as given on the deed or property map. I have
> done this with the Az & Dist plugin for many land parcels in my
> home town. But having said that let me add that getting 'closure'
> is seldom achieved. I found the accuracy of the property deeds or
> maps even with signatures and seals of licensed surveyors was very
> poor. Sometime I got definitions like "900feet N 40deg E (plus or
> minus)". It seems only the surveyors markers mean anything and the
> legal description is only a guide to help find them. Surveyors
> tell me "Here in Maine everyone knows how to get to their property
> but no one really know where it is."
>
> Unfortunately your plan didn't get to me so I can't be sure just
> what the difficulty is. If you could send me a copy, I will try to
> enter it into qGIS and see what happens. Perhaps a bug has gotten
> into the code since I last used it. But I still have my original
> plugin code so we should be able to get things working again.
>
> Here is an extract from some instructions I wrote for the local
> town government. Perhaps this will be helpful.
>
> Fred LaPlante
> Mercer, ME, USA
>
>
> 5.4 Survey Data
>
> Deeds normally provide a list of bearing and distance from a
> starting point around a property boundary in a consistent
> direction until returning to the start. The process describe here
> should accept most property descriptions as written.
>
> Survey maps may be consistent as well, but sometimes a direction
> my appear as a ‘back bearing’ due to the nature of the survey.
> These can be handled with the addition of a minus ‘-‘ sign at the
> beginning of a bearing.Failure to catch this detail can produce
> some fascinating, but useless,drawings.
>
> 1. Open or create a layer for your new feature.
> 2. Use properties to set transparency to 50-75%
> 3. Enable editing of the layer.
> 4. Open the ‘Azimuth & Distance’ Plugin.
> 5. Verify both the Layer and Coordinate System (CRS) shown are
> correct.
> 6. For most surveys, Boundary type survey is correct.
> 7. Select North type that applies (enter magnetic declination if
> appropriate)
> 8. Select Distance units. In USA this will probably be feet.
> 9. Select Angle Type: Azimuth is a compass heading, Bearing is of the
> form N xx deg E
> 10. Click ‘Capture from Map’
> 11. Move mouse to location of starting point on base map.
> 12. Under ‘Next Vertex’ enter direction and distance from survey
> or deed.
> 13. Click ‘Add to Bottom’.
> 14. Repeat above 2 steps as needed.
> 15. Click ‘Export List’ to save your entries for a later time.
> 16. Click Draw.
>
>
>
> On 5/18/2011 11:14 AM, Maurício de Paulo wrote:
>
> Hi Darren,
> I haven't worked on the plugin for a long time now.
> The terms are about what angle is given to the plugin.
> Bearing is measured from a given direction but with 180
> degrees for each side (Ex.: 90e means right. 90w means left).
> Azimuth is measured from a given direction but with 360
> degrees clockwise. (Ex.: 90 means right. 270 means left)
>
> The polar/Radial means that the angles area going to be
> centered on the point given. It's usefull when you did angular
> measures from the same point. It's used when you measure
> angles and distances from a single point to draw a curve.
> The Boundary means that the angles are relative to the last
> point you measured. It's commonly used in the descriptive
> documents when the next point is calculated with angle and
> distance from the current point.
>
> I think Fred can help more with the meaning of each term as
> many of them I couldn't translate to a common english idea.
> Fred Laplante is also involved in the project and implemented
> many of these concepts.
> Best regards,
> Mauricio de Paulo
>
> 2011/5/18 Darren Cope <darrencope at gmail.com
> <mailto:darrencope at gmail.com> <mailto:darrencope at gmail.com
> <mailto:darrencope at gmail.com>>>
>
>
> Hi Mauricio,
>
> I'm curious if you are still working on the Azimuth and
> Distance
> Plug in for QGIS? I am back to it again, and still having
> difficulties. I would like to be able to help you test if
> you are
> still developing. I have an example (attached) of a plan that
> needs to be entered using the distances and bearings shown (in
> that exact format). How would I go about doing so? I have tried
> every possible combination that makes any sense to me! I'm
> fairly
> certain I just don't fully understand the implications of the
> "Polar/Radial" and "Boundary", and "Azimuth" and "Bearing"
> settings. Perhaps you could explain?
>
> Cheers,
>
> Darren Cope
> http://darrencope.com
> http://dmcope.freeshell.org
>
>
> 2009/11/11 Darren Cope <darrencope at gmail.com
> <mailto:darrencope at gmail.com>
> <mailto:darrencope at gmail.com <mailto:darrencope at gmail.com>>>
>
>
> Hi Mauricio,
>
> I'm not 100% sure what is going on with the precision. I
> suspect the snapping feature will solve this, as the
> difference is quite small. I zoomed in to 2:1 (e.g. as
> far as
> I could) and clicked as close as I possibly could to a
> corner
> vertex, and then when I drew my feature, it doesn't line up
> (although the difference is minute in terms of actual
> distance)
>
> I guess I'm still not 100% clear on how the coordinates are
> entered. What does the 'zenith' column mean? I have a
> lot of
> plans that give angles relative to north or south (so
> they are
> displayed as Nxxdxx'xx"W or Sxxdxx'xx"E for example). I can
> convert these to a 360-based azimuth, but it would be
> nice to
> be able to enter these without doing any prior conversions.
>
> It looks like the zooming issue is fixed now!
>
> Thanks for all of your work on this--please let me know
> if I
> can provide any further information or testing for you.
>
> Cheers,
>
> Darren Cope
> http://dmcope.freeshell.org
>
>
>
> 2009/11/7 Maurício de Paulo <mauricio.dev at gmail.com
> <mailto:mauricio.dev at gmail.com>
> <mailto:mauricio.dev at gmail.com <mailto:mauricio.dev at gmail.com>>>
>
>
> Ok, thanks for the ideas. But could explain some of
> them
> to me?
> What happened with the precision of the starting point?
> I've made some tests here and the precision should
> be ok.
> I've made a teste with 0,0,0 and it drew fine.
> Could you
> tell me how to reproduce the bug?
> The snapping feature is my main priority now. I
> think this
> is a great improvement.
> DMS should be second in the list. But actually I
> need some
> inputs on how is best entered a coordinate. We're
> talking
> about azimuth here. And a DMS should have 3 numbers.
> Something like 10o14'52'' is possible and easy for the
> user. Is it ok?
> About the much larger extent... Hum... Fixed on zoom to
> selected feature. I think that should solve it.
> Gratefully
> Maurício de Paulo
>
>
>
>
>
>
> --
> Mauricio de Paulo
> Engenheiro Cartografo
> MapeandoOBrasil <http://mapeandoobrasil.blogspot.com>
>
>
>
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