Using GIS data to make smooth, accurate roads

After trying a few options out in QGIS it looks like there are no 'easy' solutions. And by easy I mean not having to hand-draw many millions of streams, lakes, rivers, and ponds across the continental United States. Maybe merging the numerous vector layers for each state I can create a single hybrid polygon/line and try compiling that.
 
Hi Chris:

I found (1) tutorial on a way to do this in QGIS thus far: :coffee:



GaryGB
 
I actually did try your suggestion last night. There must be a setting I missed because all I got was a polygon where the first and last points of the line connected instead of an offset like you mentioned previously where you'd have a thin polygon that followed the line instead of the stock texture. When I tried again, there was no option I missed; it doesn't seem to be a good option for flight simulator streamlines.
 
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Hi Chris:

Search on BLN of the SBuilderX Help file; there you will also find a link to the sections on "Append - Surfer BLN"

If you follow the link to the "Appendix" section of the SBuilderX.ini file, of particular note will be the [BLN] section, and the Join parameters.

For incidental discussions on SBuilder features used to create a "closed Line", see:



Whereas a legacy format 'minimal' source data set for Poly-lines is X,Y,Z (Lon,Lat,Alt), SBuilderX can import both ESRI *.SHP and legacy format Surfer *.BLN files that contain more fields than just X,Y,Z ...which can be used to set Start and End line width to establish a 'taper'.

The SBuilderX *.SHP Append method requires an interactive process to set Start and End width for tapered poly-lines to be created from X,Y,Z or other multi-feature line source files.

Obviously it would be be a lot of work to manually assign such a set of parameters to each individual line during import, so one can do this in the SBuilderX.ini file prior to the ex: *.BLN Append procedure, assuming one has configured the derived source data in QGIS before exporting the *.BLN source file to be Appended by SBuilderX.


FYI: A discussion (in the context of SBuilder for FS9) of SBuilder options when working with these tasks ...is here:




It may also be possible to perform these functions in Google Earth and/or FSX-KML, then use Dick's KML2BLN utility to convert *.KML data for a *.BLN to be Append-ed by SBuilderX.


Optionally, one may just intend to only assign a 'taper' to line segments rather than converting Poly-lines to Polygons.

But, preferably, one may identify a method to define Poly-line segment widths, convert them into Polygons in QGIS, then merge those Polygons having matching Water Class texture types ...so that one has a way to define these attributes semi-automatically when preparing CVX vector GUID assignments.

In the event that a SBuilderX 'Append' has too limited of a feature assignment function, one may instead be able to create a fully configured SBuilderX EXchange *.SBX ASCII text file by editing attributes for Poly-lines in that format, then 'Importing' that source to SBuilderX.



Here's a QGIS work-flow to create attributes for width as a function of 'flow direction' along defined line segments: :pushpin:



BTW: Have you seen the new USGS attributes now being made available for Hydrology ? :idea:





Some related Search results on this query at Google which may also prove informative:


Hope these ideas help a bit more with evaluating the feasibility of this aspect of your quest. :)

GaryGB
 
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I saw the high-resolution option in the USGS National Map page I use for my GIS data, but hadn't tried it until now. The areas are cut up into smaller segments which seem to be arranged by water basins instead of man-made partitions like states or latitude/longitude sections like I have been using but I am testing a section today. Hopefully this short-cuts the streamline priority issue because the streams coupled with the terrain really make flying low and slow amazing!

Thanks,
 
Returning to the original intent of the post: using a shapefile of all Missouri roads, I have edited out smaller roads, leaving layers of interstates, as well as federal and state highways using filters like "STATE_ROUT" != 'NULL'

It worked great for what I needed apart from interstate on- and off-ramps do not appear and I can't find any entry in the database that can single them out from everything else. If I include all roads, that will not only look overly busy but will crowd out the autogen and city textures that work just fine for me. While I can now navigate around using (now smooth and winding) roads, they really lose some character without ramps. Does anyone know of a way to tell QGIS to include them? I would do it by hand if I didn't need them for the whole United States.

Thanks!
 
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Gary,
I've noticed that most of what you write makes no sense the first time I read it. But I go back a day or two later (after reading a bunch of other things) and I have made sense out of enough other things that I am smart enough to grasp the solutions that you're talking about. It's a long, slow process involving learning a ton of complicated things, which would be impossible without help from people like you and a few others on this forum.

My original intent was to do terrain mesh and see what else would be possible. You've opened up enough doors that not only is mass production of high resolution mesh scenery possible, I now have so many other components coming into place that make my scenery like digital magic. Missouri (my test area) has so much going on and is so visually pleasing that it blows mountainous areas like California away now! I can't imagine what California will look like when I'm done!

Thank you very much for all the help!
 
Thanks again for the kind words. :)


FYI: I found this tutorial on QGIS: "Tutorial : How to use QGIS for Hydrology" :teacher:

https://www.engenious.com/Content/Tutorial.pdf


Of particular interest was this section: "How to get Elevations at Nodes From DEM"

...using the QGIS "Point Sampling Tool Plugin"


Also, I found this tutorial:

"QGIS Extract Ground Elevation"



This informative may prove useful for roads and other vector objects, as well as in your work with water bodies here: :idea:



GaryGB
 
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