[Qgis-user] Reproduction of Northarrow-function from ArcView 3 in QGIS

[Julian Schall]

Hello together,

 

is there any possibility known in QGIS to reproduce the Northarrow-function
from ArcView 3.0?
Background is having a tool to easy generate a way to find boundary stones
or landmarks from a known place.

 

The Northarrow-Button works as follows:

After clicking the northarrow-button you can click in the map an draw a line
and clicking again defines the end of the line (comparable to line
measurement in QGIS). Then automatically the line is labeled with the angle
(0-360° and the length from start to endpoint). Difference between the two
informations/decimal numbers gets understandable through parallel
declaration of the unit (for example: 25,7 m on top of the line and 23,5°
below the line). In ArcView that is actually a label, not a vectorlayer.



I was searching for plugins first, but didn’t find any suitable.
Then I tried to rebuild the function through line-vectorlayer with columns
“Angle” and “Length” and predefined labeling. Problems are

1.       That I couldn’t calculate the angle between north and the line
(GK3). I only found a term for UTM:
(atan((xat(-1)-xat(0))/(yat(-1)-yat(0)))) * 180/3.14159 + (180
*(((yat(-1)-yat(0)) < 0) + (((xat(-1)-xat(0)) < 0 AND (yat(-1) - yat(0))
>0)*2)))

2.       That I couldn’t manage automatic calculation of length and angle in
the attribute table after adding a line to the layer. It’s very painful to
every time calculate length and angle again.

3.       That I couldn’t display to labels respectively the content of two
attribute columns.

4.       That I couldn’t manage to label the units ° and m.


I would be very thankful for help or advices how to do that.




Julian

 

-------------- next part --------------
An HTML attachment was scrubbed...
URL: <http://lists.osgeo.org/pipermail/qgis-user/attachments/20140626/043635f7/attachment.html>