[Qgis-user] Re: Azimuth and Distance Plugin (was Re: your old qgis plugins)
Fred LaPlante
flaplante at flos-inc.com
Wed May 18 12:40:21 PDT 2011
I just tried out the map you sent me and the Az & Distance plugin worked
just fine for me. the closure seems pretty good though I didn't zoom in
to check. I did switch the n/s and E/W designations on 3 edges so that
all bearings were toward the next corner (moveing clockwise aroind the
map). other that that and being careful of my typing, I did nothing but
enter thee data.
I did specify 'boundary', 'bearing', and 'feet' for options. And I did
have CRS set to NAD83. Also I did save (or 'export') the data to a test
file and was able later to retrieve it to correct an error.
So the plug-in works for me in version 1.6.0. I suspect your problem
was mainly in making the bearings consistent from a boundary walker's
perspective.
Fred
On 5/18/2011 1:33 PM, Fred LaPlante wrote:
> 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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