[Qgis-user] rephrased;. import 3D line into a shapefile?

[Alex Mandel]

This sounds like a classic survey problem. Tools that deal with this are
often called COGO (I don't remember what that means)
While many tools and algorithms exist for doing distance and bearing,
which will allow to you plot changes in x,y of whatever plane you're
working in, the z value would need to be incorporated as an attribute.

So I would say as David stated, start with a tool that calculates an x,y
based on a distance and bearing from the previous point and tack on a z
calculation to add/subtract from the previous value. This will allow you
to use standard 3D visualization tools in GRASS, R or whatever else you
feel like using.

I think there's a distance/bearing tool in one of the plugins, shouldn't
be too hard to right, algorithm's are all over the place, GRASS has one
for sure.

Alex

David Fawcett wrote:
> Tom,
> 
> You have laid out an interesting (fun) problem.  I don't have a
> solution for you, but a few thoughts on how I would approach it.
> 
> 1.  I am not sure how you want to display the 3D shape in QGIS.  If
> you are just going to symbolize the depth by coloring the line
> segments, you could get by with a 2D shapefile and an attribute for
> depth.
> 
> 2.  I would likely write a python script using the ogr python module
> to calculate the x,y,z values for each vertex in your line and then
> create the shapefile.
> 
> 3.  Instead of using lat/lon for your spatial reference system, you
> may want to think about projecting your original point to a coordinate
> system like UTM.  This should make your calculations easier.
> 
> David.
> 
> On Wed, Mar 18, 2009 at 1:46 PM,  <mtnbiketrail at zzz.com> wrote:
>> Okay, let me rephrase the question. I did look at ogr2ogr, csv file import.
>> I have a 3D line, but only the beginning vertex has x,y,z. The line is a
>> survey of a cave, so only the entrance has a latitude, longitude, and z
>> coordinate. The rest are relative to the control point. Any suggestions on
>> how to import that?
>> Tom
>>
>>> Subject: [Qgis-user] import 3D line into a shapefile?
>>> To: qgis-user at lists.osgeo.org
>>> Message-ID: <49BFE4B3.60900 at zzz.com>
>>> Content-Type: text/plain; charset=ISO-8859-1; format=flowed
>>>
>>> Hi, I'm a beginner user.
>>> Is it possible to import a 3D line into QGIS? I have the text file with
>>> distance, compass, and azimuth and want to have it show as a shapefile(?) in
>>> 3 dimensions inside QGIS.  How would I go about doing that? Also, correct
>>> me, don't I have to use the correct datum to show 3d. Like WGS84? I don't
>>> think NAD83 can handle 3D?
>>>
>>> thanks,
>>> Tom
>>>