[Qgis-user] entering distance and bearing for polygon or polyline

[Bernd Vogelgesang]

welcome to the show ;)

actually i had a similar problem a few days ago, and i can tell you, it  
was no fun.
I didn't find any native solution.

My use case (though i do not know yours):
I had to draw new transect lines, i knew the starting coordinate, the  
distance (50m always) and the bearing.
In addition to that, I had to draw 2*2 m polygons, each 10 meters of this  
line, starting at 5 m.

So, there is the quite useful "improved polygon capturing" plugin which  
also handles polylines.
With this, you can set a fixed length for the drawing of a line segment or  
polygon side.

BUT, unfortunately it won't show the current bearing while drawing, nor  
can you set it (I already humbly asked the creator to maybe add this  
feature if possible).

So, option #1 is to take a transparent triangle like you use in school,  
hold it to the screen and draw your lines (ughh).
Option #2 is a lot of work, but more accurate:

I entered my starting coordinates (x,y), bearing (alpha) and distance in  
excel and used sin(or cos)(radians(alpha))*distance + x(or y) (sorry, I do  
mix up sin and cos all the time, so better check yourself) to retrieve my  
end coordinates.
Then i copied the calculated coordinates in separate rows like
x,y
x1,y1
x2,y2
x1,y1
x2,y2
etc.

Then, i added an id column, to indicate which point pairs should form the  
line
id,x,y
1,x1,y1
1,x2,y2
2,x1,y1
2,x2,y2
etc.

Then, I imported this table as csv with the help of the mmqgis plugin ->  
Transfer -> Geometry Import from CSV File

Lines were done.

Polygons were designed this way:
Transect Lines: Vector -> Geometry Tools -> Densify Geometry -> Factor 9 =  
a new vertex every 5 meters

With "Cad Tools" plugin, i created a parallel line to my transect line,  
distance 2 m.

Densify Geometry with factor 24 to get 2m-segments on this line.

Snapping options the transect layer set to segment and vertex and for the  
Cad Line to vertex.
Starting to draw the polygon with the "improved polygon capturing" with 2  
meters at 5m-vertex on the transect, snapping to the segment, then  
snapping to the Cad Line vertex, right click on next vertex to finish the  
polygon.
and so on and so on and so on ...

Maybe there is an easier way for that, but i couldn't find it.

I hope sth of this may help you to find an idea for your problem.

Greetz
Bernd



Am 17.11.2012, 21:54 Uhr, schrieb Jake Maier <j.m at jmforestry.com>:

> Can someone please help?
>
> When creating a new polygon or polyline I want to enter numerical values  
> for
> distance and bearing instead of pointing to the location of vertices. How
> can I do this
>
> I thought there was a popup window where you could enter the values but I
> can't find it and googling it I seem to lack the right search terms.
>
> Thanks for any hint.
>
> Jake
>


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Bernd Vogelgesang * Siedlerstrasse 2 * 91083 Baiersdorf * +49-9133-825374