[Qgis-user] Re: Azimuth and Distance Plugin (was Re: your old qgis plugins)
Darren Cope
darrencope at gmail.com
Wed May 18 10:19:24 PDT 2011
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>
> 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
>> >>
>>
>>
>> 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>>
>>
>>
>> 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>>
>>
>>
>> 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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