[Qgis-user] Starting QGIS

[Bernd Vogelgesang]

Actually, i forgot everything about ArcGIS and i'm not really eager to  
relearn it ;)
So, from your explanations i assume, that you want to construct  
rectangular polygons, right?

In this case, you might proceed like this (a "little" more work than in  
E$RI software, i fear)

you will have three layers for this:
- a line layer for your base lines
- a "CadLayer Lines" created from the CAD Tools automatically for your  
parallel lines
- your final polygon layer

I assume, you have a starting point you already know.


Make your line layer editable and draw your first line, using the button  
added by the improved polygon capture plugin to the digitizing toolbar  
with your desired lenght. Lets take your example with 6 meters.

Then you need to have installed Cd Tools, which adds a huge toolbar.

Here, you have now to select a button which says "select one line segment"  
and select with the red crosshairs your created line.
I encountered a problem, that it wasn't able to select my first line, so i  
saved the changes in the line layer with the disc symbol and then it  
worked.
After selecting your base line, it turns red.
Now you can select the next button to the right "Create parallel line"

When clicking it, a form pops up asking you for "Fixed length" which  
obvious means the distance to your selected segment. Choose 10 there.

The new layer CadLayer Lines is now in your TOC with the new parallel line  
feature.

Now, you will have to edit your snapping options to be able to produce a  
correct polygon an the basis of your two lines:
Go to Settings -> Snapping Options

Check the boxes in front of your line and of the CadLayer, select "Vertex"  
and give a snapping threshold for e.g. 1 m
You should also check the box "enable topological editing".

Now activate your polygon layer and make it editable. With the snapping  
options set, you can now simply draw your polygon over the four end  
vertices of the line.

You are done.

In case you are really beginning to work with qgis at the moment, i advise  
you to make some crucial settings in the options beforehand, otherwise you  
will run into strange things:

Settings -> Options -> Tab CRS:
Check "Enable 'on the fly reprojection' by default"
Use the next "Select..." button to choose your most common coordinate  
system

in the next section, select "Prompt for CRS", so that you will be asked  
for each new layer in which CRS it should be set up (in this case the  
automatic CADLayer, which would otherwise be in WGS84 if you do not change  
that setting, and would mess everything up, cause your values in meter  
would than be degrees!)


Hope this is what you actually want to do, otherwise .. well .. it was a  
nice training for me.

P.S
There is some plugin called "Intersect It" which constructs circles around  
points and can so stuff with that, but i couldn't quicky figure out what  
it actually does and how. But it also adds additional layers for the  
circles and the points ...)



Am 24.09.2012, 22:13 Uhr, schrieb Eliana Acosta Valero  
<eliana.acosta at igac.gov.co>:

> Thanks....!!
>
> I've found the plugin and I'm trying to work with this, but what  I  
> exactly have to do is to construct polygons with lines, and the way to  
> create those lines is with specific lengths and circles intersections...  
> I don't know if you have ever work with "Distance Tool" of ArcGIS.  
> There, I have two lines and I can close the polygon finding the  
> intersection between two circles of an specific radio, something like  
> this:
>
> _________
> |                    '
> |
> |                  10 mts
> |                    '
> |-    6 mts  -x
>
> Where,  "x" represents the point where a distance of 10 mts and 6 mts  
> intersects...
>
> Do you know if QGIS has some plugin who can do something like that?....
>
> I really appreciate your help!
>
> Eliana.
>
> -----Mensaje original-----
> De: qgis-user-bounces at lists.osgeo.org  
> [mailto:qgis-user-bounces at lists.osgeo.org] En nombre de Bernd Vogelgesang
> Enviado el: lunes, 24 de septiembre de 2012 02:46 p.m.
> Para: qgis-user at lists.osgeo.org
> Asunto: Re: [Qgis-user] Starting QGIS
>
> Am 24.09.2012, 17:57 Uhr, schrieb Paolo Cavallini  
> <cavallini at faunalia.it>:
>
>> Il 24/09/2012 17:49, Eliana Acosta Valero ha scritto:
>>> Hi! At first I'm sorry beocouse of my bad english, I'm from Colombia
>>> and I don't speak very well... But I'm starting to use QGIS, and I'm
>>> trying to do some editions but I can't find some symple tools like:
>>>
>>> - Create a new line with a specific length. (Sample: Create a line of
>>> 5
>>> meters)
>>
>> there is a plugin for this
>>
> The plugin has the bit misleading name "Improved polygon capturing"  
> cause it also handles lines beside polygons.
> It adds a button and a field for the specific lenght to the digitizing  
> toolbar.
> In editing mode of the layer, instead of the normal "add feature"  
> button, click the button which has the tooltip "Capture Line with preset  
> Edge Lenght" and set the desired length in the box. Click in the map to  
> start drawing and move the mouse for setting the direction of the new  
> line.
> Right click to finish the line.
>
> --
> Bernd Vogelgesang * Siedlerstrasse 2 * 91083 Baiersdorf *  
> +49-9133-825374 _______________________________________________
> Qgis-user mailing list
> Qgis-user at lists.osgeo.org
> http://lists.osgeo.org/mailman/listinfo/qgis-user


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