FSX Resample: LOD=Auto vs mipmaps for hi-res photo

[scott967 62]

I took a geoTiff photo with 30cm resolution and ran it through resample with LOD=Auto directive. With this setting, it created textures at all LODs 13-17. My question is, what is the advantage of doing this, rather than just creating textures at LOD=17, where I assume the mips would be used if necessary? Is there a performance difference? Is there an advantage to using the Auto LOD rather than creating separate files at various LODs, say 13, 15, and 17? With just a quick look, it seems like I could maybe do better down sampling my source data to 4.75m/pixel and then running resample LOD 13 on it, rather than letting resample do it (I think this is sim to the past where resample didn't use that great an algorithm).scott s..

[LuisFelizTirado 33]

Hello Scott,The new FS X terrain includes multiple LODs for performance reasons. As they are already in the bgl, no CPU cyles are used in calculating the missing LODs in game, thus improving performance and giving a smoother flight.The choice of LODs is up to you and you can specify your own range if you wish. The Millenium office building example includes LODs 8-17, for example, but you can choose lower resolution if you like.Anyway, it is preferable to include multiple LODs in the bgl, not just one single LOD.By the way, you can determine the Bounds of your ground wherever you wish, and are no longer limited to a specific LOD grid, for example LOD 13.Best regards.Luis

[rhumbaflappy 113]

Hi Scott.I believe if you resample at LOD17 only, the scenery will display at only a very short distance from the viewpoint, and be invisible when you are closer or farther away. That is why a range of LODs are necessary.As Luis indicates, having multiple LODs in the same BGL is the performance enhancement, as the sim doesn't need to load separate BGLs for each LOD.Dick

[scott967 62]

I was thinking of having 3 bgls, at 13, 15, and 17. That way I can "fine tune" the LOD 13 data (15 and 17 looked pretty good to me in tmfviewer). I see your point that the LOD 17 data might not be displayed at a distance, even with mips. I now need to start playing around with GIMP to see how to create these 5 channel geoTiffs with RGBABl bands.scott s..