BGL Polygons imported from OSM data

[Markus Freyt]

First of all I don't want to miss to say thank you very much for the great development of SBuilder. Its an amazing and outstanding piece of software.

Well, we use it to create an open source scenery for D, AT and CH (and may be also other countries) based on the data available from Open Streetmap.

After creating some nice Shp-files by our own internal process we use SBuilder for the last step - generating the final BGLs. The final process in short words is to "append" these shp files to a blank project in SBuilder in alphabetical order.

By this process we have already finished the whole area for all countries in DACH (vers 0.1), which is already very nice result for VFR pilots. Finally we recognized some wrong filled rectangle polygons.

Pls check the following BGL with TMFVIEWER:
www.freyt.de/CVX_switzerland.BGL

Also we have prepared some screens to point out the problem we see:
www.freyt.de/screen_CH.png
www.freyt.de/screen_germany.png

When you compare the BGL with the original shp files we imported ( pls refer: www.freyt.de/shp_data_package_switzerland.rar) you will see, that the data itself seems to be fine. Hopefully ;-) Also the rendering of the data in SBuilder seems to be ok - just the generated BGLs seem to be a bit corrupted. When you fly over these areas in FSX, you'll see some kind of areas filled with water, etc.

Well, would be nice to get your response. Would be great, if you could find a patch or some instructions for modification of our shp files in order to avoid these problems. Then we could launch our free bgls for public soon. I can already promise the result seems amazing for VFR, but also for IFR pilots

Once again: I love SBuilder. We didn't found any other software for doing such great job for our purpose...

Greetings
Markus

[Golf-HotelDelta]

Hi Markus,

I think the problem is that some of your polygons are self-intersecting, that is, they cross-over themselves:

[scott967]

Hi -- you have a tremendous amount of data there. I will take some time and look and see what I can , can't promise anything.

One thing, I think there might be a bug or two in shp2vec based on some work I have done.

I loaded up your shapefiles into my GIS software (sometimes I can learn more about the shapefile in GIS than SBuilder.)

I only looked into two so far. Waterways polylines looks OK, but the next one is landuse polygons. I see there are polygons overlapping polygons. I will have to look at the sdk, but I think it says the processing is not determinate in shp2vec when there are overlapping polygons. This is contrary to FS9 and prior, when the order within the bgl determined what was "on top of" ordering.

I will look more tomorrow, put you might want to create multiple files rather than putting into a single cvx.

scott s.
.

[Markus Freyt]

Many thanks for fast response...

"Golf-Hotel" : Yes, I have validated your feedback and I think you are right, that self-intersecting polygons are causing the problems. I found out, that the original OSM files (I export the by country / region) have sometimes problems, if f.e. a river flows from one country / region into another. In some of these cases the polygons are badly "cropped". It appears only at the border of the areas exported. So, I will report this bug to the OSMOSIS team. For the meantime I will just delete those polygons (which are sometimes even outer the area of interest) before creating the SHP files ....

Hmm, but now it becomes a bit interesting, you know? How to filter self-intersecting polygons, he,he ;-) Will take me a little while to find a mathematical solution to check, if a polygon is self-intersecting or not. Not such easy...Might be a transformation into the complex area, or something....Any advice appreciated....

Also, it could be interessting, if you might know a GIS software (like QGIS) is supporting somekind of check already. In QGis I have recognized fTools, which is checking, but its horrible slow for such huge amount of data. ;-)

Many thanks again for your help.....

Markus

[Golf-HotelDelta]

Originally Posted by Markus Freyt

Hmm, but now it becomes a bit interesting, you know? How to filter self-intersecting polygons, he,he ;-) Will take me a little while to find a mathematical solution to check, if a polygon is self-intersecting or not. Not such easy...Might be a transformation into the complex area, or something....Any advice appreciated

The simplest way would be to check each segment against all other segments for an intersection.

[Markus Freyt]

I'm very happy to let you know, that the website of the openVFR project (the free VFR scenery for Microsoft Flightsimulator X) is now online. The scenery is based on the data of Open Street Map and covers DE,AT,CH and NL. We are planning other countries as well.

www.openvfr.freyt.de

Pls visit us and see, how much your flightsimulator could be improoved. Also sign in to the newsletter, because shortly we will already push a new version online.... ;-]

Would be nice, if you could leave a comment on the webpage..Be the first!

Ciao

Markus

[scott967]

Good to hear you are making progress. Can you tell us how you got the data from OSM to SHP format?

scott s.
.

[Markus Freyt]

Scott,

yes, of course, you're welcome.

We have used an open source library for this:

BytesFall ShapeFiles v0.0.2
http://bfshapefiles.sourceforge.net/downloads.php

It is a very small and easy to use php library. There was a small bug regarding the overall area of the region we had to fix.

Markus

[HolgerSandmann]

Hallo Markus,

congrats on launching your project!

I haven't installed any of your files yet but noticed that the FAQ talks about replacing the terrain.cfg file. If that actually means switching the existing version with your custom version then I'd appreciate if you could add a note of caution to your FAQ that several existing payware add-ons (Ultimate Terrain X, Tongass X, Vancouver+, ORBX FTX, some Aerosoft products, MegaScenery, etc.) add custom terrain.cfg entries via their auto-installers and switching in a different version will break the functionality of those add-ons.

Cheers, Holger

[empeck]

Could you say something more about your workflow? I'd like to play with OSM data, and maybe try to make small BGL of my local area...

[Markus Freyt]

Originally Posted by HolgerSandmann

Hallo Markus,

congrats on launching your project!

I haven't installed any of your files yet but noticed that the FAQ talks about replacing the terrain.cfg file. If that actually means switching the existing version with your custom version then I'd appreciate if you could add a note of caution to your FAQ that several existing payware add-ons (Ultimate Terrain X, Tongass X, Vancouver+, ORBX FTX, some Aerosoft products, MegaScenery, etc.) add custom terrain.cfg entries via their auto-installers and switching in a different version will break the functionality of those add-ons.

Cheers, Holger

Many thanks for this suggestion. We have placed something like this on our website. You might wonder about the exact message. Just let me know, if you want me to change a bit....

Caution: Several existing payware add-ons (Ultimate Terrain X, Tongass X, Vancouver+, ORBX FTX, some Aerosoft products, MegaScenery, etc.) add custom terrain.cfg entries via their auto-installers. If you are using those commercial sceneries on your flight system it might be possible, that you loose those entries.

[Markus Freyt]

Originally Posted by empeck

Could you say something more about your workflow? I'd like to play with OSM data, and maybe try to make small BGL of my local area...

Hmm, in short words okay? Actually just three easy steps:

1. Take the OSM data
2. Translate the tags from OSM to FSX
3. Compile a SHP file to be placed in your FSX (see above)

You can use (mre or less) the same for terrain information and objects.
Good luck. Hands up!

[HolgerSandmann]

Hello Markus,

that heads-up should work except that it's not really a case of "might" but rather "will" break their functionality. For example, if the custom terrain.cfg entries for Tongass X are gone so are all the water bodies, roads, shorelines, etc.

You could add that people who want to run your project with those payware add-ons at the same time should repair or re-install the payware add-ons after switching in your terrain.cfg. That way their entries get combined with yours.

Cheers, Holger

P.S.: Anyone who'd rather skip the step to convert OSM data into Shapefiles can check at http://wiki.openstreetmap.org/wiki/Planet.osm whether a Shapefile extract already exists for their area of interest.