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Guest Paul_S

FS2K* ground texture question

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Does anyone know how the Microsoft engine blends the ground textures together at the edges?I remember in FS2K that the ground texture polygons had very defined edges to them. One could see where the one ended and the next started.However this dissapeared in FS2K2 and up.I haven't done any scenery design for FS2K* but I'm interested in how the textures are blended together.ThanksPaul

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Hi Paul:the (technical) answer resides in a conference paper given by Jason Waskey, presumably of the FS design team, in 2000: "Pattern Reduction in Massively Tiled Scenes". You can download a Word version of it near the bottom of this page: http://www.gdconf.com/archives/2000/ (it's almost 9MB!). I have a 2MB pdf version of it but can't remember where I got it from; the Word version I found with a Google search for the title.Obviously, some people have put a lot of thought into this. In fact, IMHO the texture tiling algorithms are one of the most impressive feature of FS - well done!Cheers, Holger

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Thanks HolgerThat's probably exactly what I'm looking for. (busy downloading)Paul

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Hi PaulIn FS2002 and FS2004, adjoining ground texture tiles are blended at their boundaries using special mask textures which you will find in the ground texture folder with names in the format #####m##.bmp. They are greyscale bitmaps 2048x32 pixels in size and contain eight 256x32 segments, although I am not clear as to how each 256-pixel segment is actually applied to a corresponding boundary. Very little research has been done on this aspect of the FS ground-texturing system and it is not described, nor even mentioned, anywhere in the SDK's.Jason's earlier article that Holger mentioned describes in some detail how to design ground textures that minimise the repetition patterning effect, but if I remember correctly it does not mention the blending masks ... (Jason, I believe, is head of artwork development, including ground textures, on the MSFS scenery development team).CheersGerrish

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That's very interesting ...I wonder how they manage to apply all those masks without requiring a huge number bending operations?All that blending must take some serious amount of processing.Paul

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Hi Paul:I haven't done any research on those greyscale masks either but I'd assume they are used in a simple overlay procedure. For example, if you want to blend two different LOD13 texture tiles that sit next to each other, one option is (and I don't know if that's the way FS does it) to start with two layers of two tiles each, one with texture 1 and the other with texture 2. When combining the two layers in the 32-point wide boundary area the 256-level mask determines the % opacity of the lower layer (though most areas in the mask files seem to be set to either 0 or 255). Finally, the blended boundary area is placed on top of the base layer with the two separate textures side by side.I don't think these basic kinds of overlays take much processor time but perhaps they do, as the long loading times of complex landclass replcement files (i.e., many different classes in the same area) suggests.Cheers, Holger

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It's starting to make sense.I think that they are generating the scenery textures on the fly based on the land class data and then cutting them up into tiles and drapping them over the mesh.It explains the long loading times and why the scenery does not load when you slew at high speed over the terrain.It also explains why FS needs lots of disk space (for all the texture generation). I'll bet FS won't run if you restrict the disk space enough.It's almost like having something like TerraScene running in the background and generating the scenery on the fly instead of having to use huge libraries of pre rendered scenery. It cuts down on disk space and gives good results. Pretty smart I must say.Paul

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