Hi guys,
I have a general question regarding the creation of a model. I have been working on creating a model of a Learjet 55, using CATIA V5. This is mainly because I used this during my degree and am basically familiar with it. I am also determined to have a model which is as close to the real thing as possible. This means if the fuselage is 2m in diameter, I want the model to have a 2m diameter fuselage as well! CATIA is awesome for this. A screenshot is at
http://members.optusnet.com.au/~tjelliffe/Learjet55.jpg
Looks very nice. :-)
The problem is that CATIA works with surfaces, as you can see in the pic, but things like blender and ac3d seem to use nodes. This makes it hard to convert into .ac format. I can save the file as either wrl, stp, igs, or cgr file formats. I have tried saving it as a wrl format, and using this directly in flightgear. The file size is around 2 Mb, and the frame rate drops from ~20 to ~2 fps. I have also tried using the demo version of AC3D, and saving directly into .ac format. This still gives very big files though.
One of the tough things about "real time" 3d modeling is figuring out how to do a nice looking model and at the same time keeping your polygon count low enough for real time rendering.
I'm guessing that some of your complex surfaces have zillions of little pieces in order to get the accuracy you are looking for.
One way to deal with this is called "LOD" or level of detail. You can specify differently detailed models for viewing from different distances. You don't need 10k polygons when the aircraft is 10 miles away. But when you are 10 meters away, you may want all that detail.
There are a lot of trade offs you probably have to accept when you start doing real time 3d modeling. Often you can compensate for lower polygon counts with fancy textures.
I'm not a very good 3d modeler though so I'm sure there are others here who can give you much better advice than I can.
Regards,
Curt. -- Curtis Olson Intelligent Vehicles Lab FlightGear Project Twin Cities [EMAIL PROTECTED] [EMAIL PROTECTED] Minnesota http://www.menet.umn.edu/~curt http://www.flightgear.org
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