Modelling for FSX using Sketchup

One of the topics that is discussed often lately on the FSDeveloper forums is using Sketchup to model for FSX. The good news for those of you who think that the learning curve of GMax is a bit too steep, is that you can use Sketchup as well if you want to model some scenery objects for FSX. I should directly note that if you plan to make an aircraft than Sketchup will not be of much use to you, since you will still need GMax to do all the animations and other advanced features that an aircraft needs. But if you want to model some scenery objects (without animations), then using Sketchup is certainly an option for you.

In this blog post I want to discuss some issues that you need to be aware of when modelling using Sketchup, as there are still some open edges. Later I plan to write a tutorial about this as well, but I need to do some more research on a few topics.

How to export to FS?

You can not export directly from Sketchup to the MDL format that is used in FSX for objects. But in Sketchup 7.1 you can export directly to the COLLADA DAE format (in earlier versions this was not possible in the free version, only in the Pro version). Once you have the COLLADA file you can use my ModelConverterX tool to convert the COLLADA file to a MDL object for FS. This MDL object can then be put into a library and positioned like any other MDL object.

But what about the textures?

Using the ModelConverterX it is indeed easy to convert the geometry of your object, but how about the textures? Most of the texture you applied in Sketchup will be exported a JPG files and that is not a format that FS can read. So you will have to convert these manually to the DDS or extended BMP format as used by FS. Also be aware that the textures as exported by Sketchup not always have sizes that are a power of two (you know 256×256 or 512×1024 or …) so you might have to resize the texture as well before you can use it in FS. I am working on a ModelConverterX feature to assist you in these texture conversions.

Watch out with the drawcalls

With Sketchup it is very easy to create your geometry and it also comes with a library full of materials, for example bricks or roof textures, that you can just drop onto your object. But wait a second, that means you will end up with a material that uses many textures (and maybe also some colours) and that will not give you best performance in FS. Each of these will add an additional drawcall to your object. So I would not advice that you model like that for FS.

But how should you model then? It is best to try to use only one texture sheet for all parts of your object. So don’t use these materials and do not apply a colour to your polygons. Try to use the same material on the entire object. I know it will cost you a little more time to map the material correctly, but it will pay you back in a better performance within FS.

Also be careful not to use the “make unique texture” option in Sketchup, as that will cut your texture into smaller pieces and then you still end up with multiple textures (even if they came from the same texture sheet).


So sum up all these items and place them in a checklist you would get the following lists of items that you need to do when you want to use Sketchup to model for Flight Simulator:

  1. Create your object in Sketchup. Be aware of the performance implications when working with materials, so try to use one texture sheet for the entire object if possible.
  2. Export your object from Sketchup to the COLLADA DAE format.
  3. Import the DAE file in ModelConverterX and export it again as FSX MDL file.
  4. Convert the textures that Sketchup exported to a format that FSX can read (DDS is preferred). Be aware that you might have to resize them so that the sizes are a power of two.
  5. After that you can use the MDL file and the textures like any object for FSX, so you can put it in an object library and place it with your favourite object placement tool.

And most of all, have fun! In the end you should notice that it is a lot of fun to make your own objects for FS and if you found the learning curve of GMax to steep, then Sketchup might be more fun for you to use.

12 thoughts on “Modelling for FSX using Sketchup

  1. hi, Arno,

    i am trying to use Google Sketchup to create a McDonald’s sign for my husband, who is an avid FSX user. i export it from Sketchup 7.1.6860 as a COLLADA DAE file, and attempt to import it into ModelConverterX, and i get the following error message from ModelConverterX:

    “An error occured during importing the selected file

    Object reference not set to an instance of an object.

    at ASToFra.DAEReader.FindNode(Node start, String url)
    at ASToFra.DAEReader.FindNode(String url)
    at ASToFra.DAEReader.ProcessNode(Node node, SceneGraphNode root)
    at ASToFra.DAEReader.ProcessNode(Node node, SceneGraphNode root)
    at ASToFra.DAEReader.Read(String filename)
    at fileName)
    at ASToFra.MainWindow.bwImporter_DoWork(Object sender, DoWorkEventArgs e)”

    i just updated Microsoft .NET Framework 2.0 with Service Pack 2 Update (KB976569) — and running Windows XP Home SP3.

    i tried this several times with a model i downloaded from Google’s 3D Warehouse, and with a simple model i created myself.

    i hope you can help me out with this problem, because Sketchup is much much easier to use than GMAX.


  2. Hi, i have problem with textures. Converted model is showing in FSX and textures are in .DDS format. The problem is that object is black and without textures. Everithing is in it’s folder

  3. Hi,

    Are you sure the textures are in the right folder? Also be sure that you first used the mass texture editor and only then export to mdl.

  4. Once you have made a FS MDL file, you can use it in ADE as well. Just like any other MDL that comes from a modelling tool like GMax.

  5. I have put the sketchup file into mcx and it shows the model and texturs. I can export the textures but cannot get an mdl or even a bgl to export. I go through the steps and there are no errors but nothing shows in the folder I exported it too.

  6. Hi i am using google sketchup for making a plane but i have no idea how to get animations like ailerons and flaps etc can you help me????

  7. How do I get the textures not to be upside down everything that I model and send to FSX. The model is there but the texture(s) seem to be all upside down or all of it looks like a piece of wrongly placed puzzle.

    Thank you

    Gus N Akel

  8. I started using Sketchup last week, this week I have three very nice realistic buildings placed in FSX and working well with little or no FPS hit. Thanks arno for your amazingly simple to use tool (MCX). It really takes all the science out of the conversion of textures. Is there a rule of thumb as to how much detail to add to Sketchup objects? I noticed if you use the transparent glass in windows you can get a flicker effect. and also the textures render the building as brand new, not weathered, which leads to the question is it advisable to create photo textures? then just lay them over the buildings exterior? Any drawbacks or advantages?

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