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Guest Stratobat

Image tool and photoreal.ground

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I'm experimenting with photreal ground textures and have had good results up to the point of converting to dxt with image tool.I use the 2000 resample tool and save the 256x256 bitmap slices created before sending them to image tool. The image slices come from a larger bmp that I resampled to @ 4.8 m/px before submitting to resample tool and look pretty good.As they are they would blend in in faily well with the adjacent landclass. However, when I submit them to image tool for dxt compression and mipmaps, my troubles begin. The point of the problem is that image tool tends to add a "purple haze" (sorry Jimmy) for lack of a better term. From what I understand this is a result of compression artifacts. Even if I decrease the color depth I get similar results.I have succesfully converted hi-res digital photographs for use as object textures with good results and I'm just wondering if anyone has "trick" for for getting even results with terrain textures.ThanksRellek

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Hi Rellek,I think that you can stay with 8-bit bitmaps (that use a 256 color palette) and you do not need to compress to DXT. You need the mips though.At least this is possible if your BGL contains VTP polygons. In this case you can add an alpha channel (gradient transparency) so that the photoscenery blends nicely with the default. However as the palette is used both for the color and the transparency you can get strange artifacts. For opaque slices I would stay with 256 colors. For gradient transparent color, I would reduce colors to 128 and alphas to 16, before using the ImageTool to generate the 8-bit bitmap with alpha.I develop the last sentence. You can start with a 32-bit bitmap where each pixel has 4 bytes (3 for color and 1 for alpha) and present this bitmap to Image tool. You can force ImageTool to generate an 8-bit bitmap. But every pixel in the input bitmap has one value out of 4 trillions (2 exponent 32) and ImageTool has to generate a bitmap where every pixel has one value out of 256. In general this task is impossible. If you reduce the colors to 128 (7 bits) and the levels of transparency to 16 (4 bits) the task that ImageTool has to accomplish is much easier. The input bitmap now has only 2048 (2 exponent 11) different pixels. Normally the artifacts are small.I am sorry for the deviation from your topic.Kind Regards, Luis

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Hi all,I have here an illustration to this way and the rule for custom textures by VTP polygons "8bit, mipped, vertically flipped, with alpha" http://www.volny.cz/stoje/scen/alfa_custom.jpgNow, what is the theoretical maximum number of the alpha grades for testing texture with 5 colors? Sure this all is quite unimportant, when the next version of FS can bring richest graphical format for custom textures and moreover the FS pilots don

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Hey that looks pretty cool :-cool Just wondering though if compressing with DXTBmp will also give the purple haze ???Regards,Stratobat

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>I'm experimenting with photreal ground textures and have had>good results up to the point of converting to dxt with image>tool.>>I use the 2000 resample tool and save the 256x256 bitmap>slices created before sending them to image tool. The image>slices come from a larger bmp that I resampled to @ 4.8 m/px>before submitting to resample tool and look pretty good.>>As they are they would blend in in faily well with the>adjacent landclass. However, when I submit them to image tool>for dxt compression and mipmaps, my troubles begin. >>The point of the problem is that image tool tends to add a>"purple haze" (sorry Jimmy) for lack of a better term. From>what I understand this is a result of compression artifacts.>Even if I decrease the color depth I get similar results.>>I have succesfully converted hi-res digital photographs for>use as object textures with good results and I'm just>wondering if anyone has "trick" for for getting even results>with terrain textures.>>Thanks>RellekUse Elrond Elvish's FS Texture Converter and select DXT1 with Alph using >Nvidia Method< if you use the default FS2k method you will get the results you describe

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