Have been installing into FSX some Photo real sceneries, which seem to load OK but don't look as good in FSX.

Read in one of the Forums that it's possible to make some FS9 textures FSX compliant, so I did some searching

and reading, and trying a few things, among them bmp2dxt3. Nearly all these FS9 textures are in WXT1 4m resolution format and decided to convert a whole texture folder to DXT3. The resulting bmp's were larger in size but once inside the sim there appeared to be less blurr and took longer for textures to start blurring. This is as far as I got and now

would like to learn about converting them to DXT5 but some googling came up with developer's info that was/is way above my head. Some info on what software to use and guidance/advice would be much appreciated, info on

converting the accompanying bgl's would be a bonus.

 

Thanks

There is no reason to convert a DXT3 texture to a DXT5 texture unless you want to edit the Alpha channel.

 

Compressing an already compressed texture could result in a loss of quality.

 

Better off to leave well enough alone.

 

regards,

Joe

Joe, thanks for the input. I've given up on this after having texture loading issues after conversion.

 

Regards

The main reason a FS9 texture looks blurry is because it is a lower resolution that what works best in FSX. 1 m per pixel is the default in FSX, FS9 default is not at the level and can't go any more higher in resolution, whereas FSX can

"Blurriness" is probably a function of the actual spacial resolution of the bitmap used (best in FS9 is approx 4m per pixel, while in FSX resolution can be a high as .06m).  Then there is the use of mip-map spatially reduced resolution.  I think in FSX also, it is possible to discretely store lower-resolution bitmaps (created by the resample tool) instead of using mip-maps.

 

All the DXT formats provide color-space compression in a lossy way.  This compression can also result in blurriness.  DXT compression works on a block-scale.  The bitmap is divided into 4x4 pixel blocks.  Each block then consists of 16 pixels that uncompressed are 24 bit 888 RGB color space.  The compression works by defining two reduced color resolution endpoint colors that are expressed as 16 bit 565 RGB color space colors.  Then two additional colors are computed by taking a linear interpolation between the two endpoint colors.  These computed colors are computed as 24 bit 888RGB color space.  So given the 4 possible colors for each of the 16 pixels in the 4x4 block, each pixel is assigned 1 of the 4 colors.  This is the same regardless if DXT1 3 or 5 format is used, with the exception that in DXT1, a block with alpha gives up one of the four possible colors (for the alpha) and so there are only 3 available colors to chose from.

 

What often isn't considered, is the method by which the compression color endpoints are chosen.  This can have a big effect on how good the compressed image looks compared to the uncompressed.  (The same problem can be considered with how mip-maps are generated).  Rarely is it stated what algorithm is used for compression endpoint selection.  AFAIK, many maybe most implementations use code that was developed by Nvidia labs.  Whether or not that algorithm is optimal for photo ground textures I have no idea (an important part of the algorithm is speed so there is a trade between speed and accuracy).

 

At any rate converting from one DXT format to another should have no benefit from a color resolution or accuracy consideration, if the the same algorithm is used in every case.  The only exception being for DXT1 with alpha.  (Note for DXT1 the presence of alpha is determined on a block-by-block basis, so only blocks that require alpha are affected).

 

FSX resample does not produce DXT bitmaps, rather undefined compression is used and the photo data stored within BGL files.  Resample has a "CompressionQuality" parameter which I guess can affect exactly what compression is done.

 

scott s.

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Have been installing into FSX some Photo real sceneries, which seem to load OK but don't look as good in FSX.

Thanks

Does it look good if you hit pause and wait a little while to let texture loading catch up?

Does it look good if you hit pause and wait a little while to let texture loading catch up?

They sort of looked OK, only trouble was that it took much longer to load everything and after a while began to experience some scenery stutters.