FSDS objects and smoothing

Unlike many other formats the FSDS FSC format does not store the normal of each vertex separately. This means a little more work for me when reading the format when polygons are smooth shaded. Until now the FSC importer just ignored the fact that some polygons are smooth shaded. But I have changed that now.

In the next development release the smooth shaded polygons are supported as well. ModelConverterX will average the normals of all polygons that meet at a certain location when they are smooth shaded. That results in a smooth shaded effect. I am not sure if this is exactly the same way as FSDS exports the smooth shaded polygons to a FS2004 or FSX MDL file, but it seems to work well. Below you see a picture of a model that has smooth shaded polygons and as you can see the normals appear as you would affect.

Next step is to detect when an object is smooth shaded, so that I can also support writing this attribute to a FSC file. But that’s for a next update.

Image2013-09-09 2120.06.675

Back home again

image

For the last three weeks this was the scenerydesign.org headquarters. Needless to say I didn’t spend much time on flightsim at all. We had a great holiday in Normandy and Bretagne. I’ll probably spend a day or two to unpack, clean and store all vacation stuff again, and after that I’ll be turning my attention to flightsim again as well.

Luckily not to many new bugs were reported during my holiday. So my plan is to finish some of the work in progress that I started before the vacation. But who knows these priorities change again when I catch up with all forum discussions.

Is it easy to waste performance?

Let me start with the answer to the question I posed in the title: YES.

Earlier this week I introduced a scenProc update that could handles holes in shapefile polygons. This new features used the functions I have to do boolean operations on polygons. Things like intersect or subtract two polygons. This functionality is also used in the ground polygon wizard of ModelConverterX or in the SPLITGRID step of scenProc. Initially I noticed that loading the shapefiles with holes took quite a bit longer than loaded the shapefiles before.

So time to have a look where that extra time was spend. Not really surprisingly it was inside my boolean functions. After I used a profiler to see in which functions most time was spend (it is always in the functions that you don’t expect), I was able to optimize the algorithm quite a bit more.

So compared to the beginning of the week, my boolean functions have become at least 6 times quicker. That will not only be useful when importing shapefiles with holes, but also when performing the SPLITGRID step. So I hope you enjoy the extra speed.

Looking for presenters

As FSDeveloper we are trying to organize an online conference for FS developers, with the aim to share techniques, knowledge and just have fun. We are now one step closer to organizing this conference, as we have our call for presenters ready. So do you have a topic that you would like to talk about for other developers, let us know!

Features with holes

Holes are often used in shapefiles, for example to mark an island in an water polygon or to mark a clearing in a forest polygon. Until now scenProc did not support holes, so they were ignored when importing shapefiles. As a result of this the autogen generated would not be correct.

The scenProc code that handles the splitting of features into the autogen grid does not know about holes and also the autogen polygons in the AGN file don’t know the concept of holes. So therefore I have added functionality to the SHP importer to remove them. Instead a cut is made in the polygon, so that the entire shape can still be represented as one polygon. After that they can be processed like any other shapefile.

Interestingly you can have island within holes again (and that island can have a hole of itself). scenProc should be able to handle such situations as well, as you can see in the picture below. Although I haven’t tested it to the extreme.

The new functionality will come at a small performance cost. When importing features with holes scenProc has to do additional work to correctly represent them. So for complex files this can increase the loading time a bit. But of course you get support for the holes in return.

If you still have a file with holes that doesn’t work correctly please let me know.

holes

Be careful for narrow houses

narrow house 6Two users recently reported the same problem to me with autogen files made with scenProc. In Annotator they could not see all the buildings and after saving in Annotator many of the buildings were gone.

It turned out this problem was caused by very narrow buildings. So I want to warn all scenProc users of this problem. There are two causes for narrow buildings:

  1. Your data already contains them
  2. The SPLITGRID step made them

For the first case there is not much I can do, so just check your data. But to be honest the second case is most likely the cause of this issue in most cases. Normally the SPLITGRID step does make sure all features are divided along the borders of the autogen tiles. So if a polygon crosses the border it is split into two polygons.

Now what would happen if you house just crossed the border a tiny little bit? That would result in that tiny bit being sliced away from the house and being represented as a separate polygon (and thus seen as another house). This can result in very narrow houses in some cases.

The obvious solution for this is to not slice the houses, but instead just put the entire footprint polygon of the house in the terrain tile where the centre is. This option is already possible with scenProc, it is the second argument you can give the step.

Let me show you two examples of how to use it. The first case assumes that you load all your building footprints from a separate file, let’s assume it is called buildings.shp. In that case you can tell scenProc not to slice the buildings by using the following command:

SPLITGRID|AGN|FROMFILE=buildings.shp

Another case would be where you loaded OpenStreetMap data. In that case the buildings are not in a separate file. So you would need to filter on some attribute. For example:

SPLITGRID|AGN|building=*

Tree detection – part 4

It’s a while ago that I posted about the progress of my tree detection efforts. So here is a quick update. Some other things kept me busy, so there hasn’t been too much progress recently.

I was able to run the tree detection algorithm on the entire island of Nantucket now. It took around 3.5 hours. Below you see a screenshot of the result. I have to be honest that I took the screenshot from a good angle. There are areas where there are quite a few false detections, which results in trees on locations where they should not be. Mainly in the water. So my efforts will be focussed on finding a way to eliminate those.

In one of my earlier posts I mentioned that polygonal autogen vegetation did not work well, since trees not always show up. But that was wrong. I ended up added a buffer to my detected areas to make them a few pixels bigger and that was enough to get the trees displaying. I now I conclude that the polygonal vegetation is probably still the best way to go.

Image2013-06-16 1715.10.962

SPLITGRID? Check!

check-markIn my bug reporting system I can see that it relatively often happens that people run into trouble (crashes) because they remove the SPLITGRID step from their configuration file. If you then try to create autogen features scenProc will crash. This is because I assumed that the SPLITGRID step will be done first. This step will make sure all features are divided correctly in the terrain grid used by FS.

So to prevent such crashes from happening, I have now added an extra check to the validation of your configuration file. If the SPLITGRID step is not present before using the steps to create the autogen you will get an error.

I hope this will help to prevent this common mistake from happening.

I flipped it

Yesterday I fixed a bug in the scenProc step that imports AGN files. There was an issue in this step that resulted in part of the autogen features being displayed wrong. They were vertically flipped.

So if you are using the import AGN step in your workflow, please update to the latest version and run your configuration file again. Else you can have wrong results.

BGLComp SceneryObject flags

A few days ago I added support to ModelConverterX to read the additional options like <NoShadow /> or <NoAutogenSuppresion /> from the object placement code in the BGL file. Initially I had some trouble to find out where these options ended up in the binary code, since it was not documented in the otherwise excelent description that Winfried Orthmann made a while ago.

After the latitude, longtide and altitude the description says there is a short that stores if the altitude is AGL or not. But actually this short can store much more than that. It more acts like a set of flags for multiple options. Here is the list of possible flags:

0x01 AltIsAgl
0x02 NoAutogenSuppression
0x04 NoCrash
0x08 NoFog
0x10 NoShadow
0x20 NoZWrite
0x40 NoZTest
Just wanted to share this, in case other tool developers are struggling with the same in the future.