[Qgis-user] Re: Azimuth and Distance Plugin (was Re: your old qgis plugins)

Wed May 18 10:13:18 PDT 2011

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>
>