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FSX Textures - DDS vs. BMP

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gadgets

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I have converted all my FS9 models for use in FSX. I created FSX textures for all models, assigned the _LM version to the self-illumination "slot" and saved everything as BMP. Things look great in the daytime, but the model textures at night are quite light - much lighter than they were in FS9. I then converted one of the _LM BMP textures to DDS. The brightness of the night display became much closer to FS9, but the mapping is wrong (lighted windows appear where there are no windows in either the day or night textures). Is it necessary to re-map when using DDS textures?

Thanks in advance,
Don
 
Hi Don,

That is interesting, I would not have expected to see any difference between using a DXT BMP file or a DDS (they are almost the same anyway).

Which tool did you use to create the DDS? With most tool you will have to flip the texture to get the correct mapping. If you use ImageTool that is done automatically.
 
Thanks for the reply, Arno. All textures were created with Photoshop elements and converted to DSS/DTX1 with DXTbmp. I did not flip the textures, so that's probably the problem. Re the lighter display, I've since noticed that it is only lighter on the south side of the buildings. If I go around to the north side, the texures are much darker. So, the difference may be due to something fancy FSX is doing (or trying to do).

Don

EDIT: I can confirm that, when saved with ImageTool, the DSS texture displays properly - and the same as BMP (i.e., both much brighter than the same texture in FS9). I suspect the darker display earlier was due to the texture not being flipped and, hence, the wrong section of the texture sheet being displayed.
 
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In FS9 there was the problem with north/south sides of my bridges having different lighting. (32bit bmp/DXT1 with an alpha channel).

Are you sying this is possible to solve in FSX by using DXT1 files with the .DDS extension, converted by Imagetool?
 
gadgets said:
Thanks for the reply, Arno. All textures were created with Photoshop elements and converted to DSS/DTX1 with DXTbmp.
Click to expand...

Martin's DXTBMP.exe will not create FSX compliant DDS files, unfortunately.

In fact, I've found even DDS textures created via the nVidea plugin cannot be "read" by Imagetool.exe at all, even though they do display properly in FSX.
 
n4gix, I don't have any problem reading nvidia-generated dds files with Imagetool. Are you using the newversion from the FSX SDK?

Don
 
bob5568 said:
Is there an advantage for using dds over the dxt1?
Click to expand...

Bob, DDS textures are also DXT1 or DXT3 themself. So you can not compare them in that way. Actually the DXT BMP textures we used in Fs2004 are already DDS textures in principle, just with a BMP extension.
 
Thanks Arno, what's confusing me is all the talk about dds. If we've been using them for years, why are we referring to them now in this new way?
 
arno said:
Bob, DDS textures are also DXT1 or DXT3 themself. So you can not compare them in that way. Actually the DXT BMP textures we used in Fs2004 are already DDS textures in principle, just with a BMP extension.
Click to expand...

Er, sort of... the DXT3 and DXT1 textures a la FS9 aren't vertically flipped...

The major advantage of DDS vs DXT3.bmp files is that they don't have to be dynamically "flipped" by the CPU before being sent to the video card.

Also, ACES claims that DXT5 compression is a better, more robust algorithim than DXT3, and therefore less apt to artifacts and degradation.
 
gadgets said:
n4gix, I don't have any problem reading nvidia-generated dds files with Imagetool. Are you using the newversion from the FSX SDK?

Don
Click to expand...

Actually, I'm using Imagetool.exe from the beta SDK/SP1a.

Imagetool reports an "Failed to load... Could not read image data."

If I load them in DXTBMP and export as 32bit, Imagetool will load them and convert to DDS/DXT1 or DXT5 as appropriate with no problem.

DDS files Exported from DXTBMP will not load at all in FSX though.

Bill
 
bob5568 said:
Thanks Arno, what's confusing me is all the talk about dds. If we've been using them for years, why are we referring to them now in this new way?
Click to expand...

I guess a better question is why they called them BMP in the past :), to me it would make more sense to call them DDS right away. That makes it very clear they are compressed, as the BMP extension can be quite confusing.

n4gix said:
Er, sort of... the DXT3 and DXT1 textures a la FS9 aren't vertically flipped...
Click to expand...

That flipping is a very special feature :). At work we also have some tools that use DDS textures and they don't all have the same standard. So some use DDS vertical flipped and some don't. It seems nobody is exactly sure that the actual standard is.

n4gix said:
Imagetool reports an "Failed to load... Could not read image data."
Click to expand...

Yes, I have seen the same issues. If you look at the file size, there is a few byte difference there as well. While I always thought the size of a DDS texture was fixed (for a given pixel size).
 
arno said:
That flipping is a very special feature :). At work we also have some tools that use DDS textures and they don't all have the same standard. So some use DDS vertical flipped and some don't. It seems nobody is exactly sure that the actual standard is.
Click to expand...

The Microsoft DirectDraw Surface (.dds) file format is used to store textures and cubic environment maps, both with and without mipmap levels. This format can store uncompressed and compressed pixel formats, and is the preferred file format for storing DXTn compressed data. This file format is supported by the Microsoft DirectX Texture tool (DXTex Tool), as well as some third party tools, and by the Direct3D extensions (D3DX) library.

The chief reason why ACES chose to use the DDS format was because of it is the final format used when sending DirectX content to a video card. The reason for "pre-flipping" the image data is to eliminate the overhead in having it "flipped programmatically" at runtime by the CPU before sending the data through the pipeline to the video card's memory buffer.

As for which type of compression to use in FSX, I would recommend following the suggestions of ACES:

1) If there is no Alpha channel, use DXT1 (no Alpha) - 8:1 compression

2) If there is a single color Alpha (0,0,0 or 255,255,255), use DXT1 w/Alpha - 6:1 compression

3) IF there is a "complex Alpha", use DXT5 - 4:1 compression

Note that from the S3TC schema the major difference between DXT3 and DXT5 is the type of Alpha supported.

http://en.wikipedia.org/wiki/S3TC

DXT3 is best for "Sharp Alpha"
DXT5 is best for "Gradient Alpha"

I hope this helps! :)
 
Bob (me) asks.... can I ask a dumb question? Everyone says.... Better than anyone we know!

Went to the Wikipedia link.... haven't had that kind of math in decades. Best I got up to was Probability and statistics. Anyway, is there an easy definition between sharp alpha and gradient alpha? Bob
 
jyarddog said:
Bob (me) asks.... can I ask a dumb question? Everyone says.... Better than anyone we know!

Went to the Wikipedia link.... haven't had that kind of math in decades. Best I got up to was Probability and statistics. Anyway, is there an easy definition between sharp alpha and gradient alpha? Bob
Click to expand...

Simple definitions are my specialty!

sharp alpha - alpha's that use single levels of 'gray' for sharply defined areas - Explicit alpha

gradient alpha - alpha's that have multiple shades of 'gray' within defined areas - Interpolated alpha

sharpvsgradientalpha.jpg

Shot at 2009-12-28
 
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Hello!

We try to use the DXT5 to use the "smoother" alpha effect. One thing is not clear for me. If we use any alpha channel in FSX, if the alpha channel is darker than 50% than it is immediately completely transparent. Look at this:

n6atrs.jpg


This is a fence with DXT5. Left upper corner you can see the alpha channel. As you can see below 50% the transparency is full.

At some sceneries I have seen very good alpha channels without this effect. So it should work.

Is there a different gmax material setting which infulence this effect?
 
gadgets said:
I have converted all my FS9 models for use in FSX. I created FSX textures for all models, assigned the _LM version to the self-illumination "slot" and saved everything as BMP. Things look great in the daytime, but the model textures at night are quite light - much lighter than they were in FS9. I then converted one of the _LM BMP textures to DDS. The brightness of the night display became much closer to FS9, but the mapping is wrong (lighted windows appear where there are no windows in either the day or night textures). Is it necessary to re-map when using DDS textures?

Thanks in advance,
Don
Click to expand...
HI guys! After a long long period completly away from the simulator world I'm coming back and I have some serious issues about bmp vs dds textures, I have this fsx Antonov An-70 model and the textures are poor at all....my question I think here makes sense acccording to the question made, how can I transform/convert this poor textures into dds ? Im using GIMP dxtbmp and fsrepaint v2.2
 
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