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Hi Folks.

I am fairly new to re-painting although I have reworked a few registrations on various fuselages. I am using FSX and Paint Shop Pro 2020 (PSP) in Windows 10 64 bit. I am re-painting the Carenado Phenom 300 and I know that it is a difficult one to start with. However, I am quite patient and careful and am taking my time. So far I am reasonably pleased with my work on the engine cowling registrations. I have not attempted the bezier curves yet for the stripes. Something to look forward to!! Anyway, I need some advice and perhaps a tip or two regarding the DDS texture Alpha channel. It has disappeared from DXTbmp!!

Here is my work flow, bear in mind that I am a relative newcomer with no real knowledge of how the textures interact. I have made a copy of the original white aircraft texture folder and renamed it as a test folder in FSX. I have also placed it on my desktop and made a second copy as a working textures folder. Within the texture folder are :- Cept_ext1.dds and Cept_ext1_spec.dds (the two main fuselage textures). Also, Cept_ext2.dds and Cept_ext2_spec.dds (the wings and tail fin).

I open the Cept_ext1.dds in DXTbmp and send to editor (PSP) and rework the texture then save it as a psp file to preserve the layers. I also save as a bmp file. These files go to my desktop working textures folder. I then open the bmp file in DXTbmp and save it back to FSX as a DDS DXT5 file, overwriting the original Cept_ext1.dds file. Remember I have it backed up, so don't panic...LOL

I then open FSX and view my work taking note of any further adjustments required. The engine cowling is split horizontally with half of the registration below the split and half above. This makes for some careful placing of the letters which are also curved in the texture sheet to allow for the curve of the engine. Anyway, I have now noticed that the Alpha channel has disappeared from the small box up in the top right corner of DXTbmp. I am unsure what the Alpha channel is and its disappearance seems to have made no difference to the visual appearance of the aircraft in FSX. Can anyone shed some light on why it has gone? I have no idea what I have done. It is stiil showing when I open the saved original DDS file to check. However, I am unsure if my final save back into FSX when I am happy with my repaint, will also not have the Alpha. If you can follow my train of thought.

I would appreciate any help and advice regarding my workflow and why the Alpha has gone from my working texture. Also, if you don't mind, some info on the Alpha and what it does.

Apologies for the long post.

Best Regards...Ken.

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Posted (edited)

Usually, when people find that they have 'lost' the Alpha Channel off their image, it is because they have 'saved' their file rather than 'exported' it. This isn't always the case with every image editing program, but it is a pretty common cause for this. Here is the drop away menu you get in Paint.net when saving a DDS file. On this image you can see that you would be able so save files with an alpha channel:

OwXSVqA.png

Not every image supports having an additional alpha channel, so it can often be the case that when people save an image which originally had an alpha channel in another format, it might either lose that channel because the new format does not support alpha channels, or if it does support them, an option to include the alpha channel was not selected when saving. 

So, what is an alpha channel anyway? As I am sure you know, most texture files and electronic images replicate how the human eye works (to some degree) by using three colours (Red, Green and Blue). To do this, paint programs, and the image files they use, commonly split the colours into three channels, and it is combinations of these three colours which give you your finished image, which you see on a composite of the three channels (there are some weird exceptions to this, such as how yellow is created, but we'll leave that for another discussion).  These images are called RGB images for obvious reasons.

But sometimes you will want a texture to have transparent areas, for example in order that the windows are 'see through' on your model, or when you see a propeller disk appear as though it is spinning. For this transparency to display, your image file needs an alpha channel. Unlike the regular Red, Green and Blue colour channels, the alpha channel is grayscale. Typically it will be capable of displaying 256 different levels of grayscale, from totally black, through 255 intermediate gray tones, to totally white. Anything area which is completely black on the alpha channel will display as transparent, any area which is white will be opaque. So if an area on your channel looks black, and that area lines up with the windows on your main texture image, then your windows will be transparent. If that area was a mid gray colour, the window would be partially transparent. Like this for example:

2jVZSAP.jpg

qOO77SG.jpg

Not all alpha channels have the same capabilities and this is what all that 'DXT 1' and 'DXT 3' option stuff is about when you are using your paint programs. The option you pick for this will affect the alpha channel's capabilities and also its file size.

DXT 1 only has a 1 Bit alpha channel, which means that channel can only display either fully black (transparent) or fully white (completely opaque). So this is good for making either an open doorway or a broken window appear fully transparent.

DXT 2 is a 4 Bit alpha channel, which means it is capable of displaying sixteen different levels of transparency, i.e. you can paint completely black, completely white, or 14 graduated gray tones between these. This would be okay for aeroplane windows which were perhaps dirty, with not too much in the way of reflection detail.

DXT 5 is the same Bit depth as your main image format (16/24/32 etc), so a DXT 5 alpha channel can display 256 levels of grayscale and can therefore smoothly vary its level of transparency. This would be good for windows with lots of different dirt and reflection detail on them, of varying transparency.

So, typically, when using alpha channels (unless it is a paint kit which already has them) you would make your main texture and get that all nice, then you'd select all your window areas, then you're choose to create/add an alpha channel, then you'd paste your window selection areas onto that new alpha channel, then you'd make sure they were either black or a suitable grayscale tone on the alpha channel, and then you'd save/export it in a format which supports alpha channels.

Edited by Chock

Alan Bradbury

Check out my youtube flight sim videos: Here

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Hi Chock.

Thanks for the info. I am so used to making 'simple' graphics for my wife's card making hobby that I was unaware or forgot about the Channels feature. I'm thinking as I type this, that PSP does indeed have a Channels option. I'll need to investigate this further. The info you supplied is very helpul in explaining the differing tpes of texture. I'll go and have another look at this and report back.

Chin Chin.

Ken.

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Posted (edited)

I will add that Carenado and Alabeo paint kits are very often a bit bizarre. They tend to go about things in a bit of a convoluted fashion which sometimes does not make repainting easy. The reasons for this could be many, but having taught people Photoshop for years professionally, I can tell you that from the experience of having met literally thousands of people who have used Photoshop for a long time, who have then come on a course to learn the advanced stuff from me, it is often the case that they can do pretty much everything they want to do, but not necessarily in the best or easiest way. So they've learned some if not to say bad, then at least rather inefficient ways to do things, and much of what I end up teaching them, is the 'other ten ways you can go about doing things', which then arms them with a fund of knowledge to be able to pick the best method for a particular task at hand. 

I think there is a bit of this going on with Carenado's stuff. It looks good in the end, but sometimes when you look at their paint kits, you can observe that they've gone about it in a way which was perhaps not the best, particularly when their methodology and production techniques end up being the basis for the paint kit. It can leave you scratching your head a bit when you see their paint kit files.

In the end, if it works, then it isn't wrong, but when it comes to doing textures and how people go about it, in the same way that you can make a cup of tea by boiling water in a pan on a gas stove, it's easier to use an electric kettle. But if you never knew a kettle existed, you'd be forgiven for using a pan. 

Edited by Chock

Alan Bradbury

Check out my youtube flight sim videos: Here

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Posted (edited)

Hello Alan.

It looks like PSP has an Alpha Channel option but it seems to be tied in to the Mask feature. If you don't mind, I'll continue with my changes to the aircraft main texture then come back to you for further advice on making the Alpha. I'm not fully up to speed with it yet and do not fully understand it. I need a bit more educating LOL.

Best Regards...Ken.

p.s. I feel that I fall in to the pan on the stove group at the moment!!

Edited by kenny584
Typo.

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Posted (edited)

Feel free to ask questions. Remember, nobody is born knowing this stuff and there are no stupid questions, just stupid answers on occasion. Above all, have fun with it.

If it starts to become annoying and things don't go to plan, leave it for a while, have a cup of tea or whatever and them come back to it. Half the time when you get back feeling fresh you'll spot what was going wrong straight away. Remember, we do this for fun, so don't let it turn into a chore.

Edited by Chock

Alan Bradbury

Check out my youtube flight sim videos: Here

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In most planes the alpha-channel in the diffuse files are for setting the amount of gloss/refelection of the model and NOT for making some parts of the plane transparent.
Windows in contemporary models are modeled in the 3D structure and have nothing to do with black spots in an alpha layer.
Years ago sometimes black spots on an alpha were used for transparency and creating windows , thats hardly the case nowadays.


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"Non licet omnibus volare cum aquilis" (Azzurro)

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Hello Leen.

Thanks for your input. I appreciate it. I understand what you have said regarding the window 'holes' in the aircraft model, as I have made use of the Boolean tool in FSDS and made a transparent glass texture to fit that hole. This is in buildings that I have made for my own use in various airfields. However, could you explain the difference between an Alpha Channel and a specular texture? I do not as yet understand that part of aircraft textures. I am keen to learn. I am working on a repaint for the Carenado phenom 300 and am making good progress with the painting side of things but not up to speed with the technical differences in the texture sheets.

Best Regards...Ken.

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Hi Ken

In MSFS >> we have three main-types of texturefiles

Diffuse files representing the colors/livery of the aircraft  , these file have an alpha for adjustment gloss/reflection.

Specular files  for setting specularity on the aircraft , these files have an alpha too.

Bump files for creating kinda faked 3d effects on fuselage and wings. E.g. rivets, platelines etc.
I am not sure about these bump-files having an alpha or not, as far as I can recall its not the case, maybe they have an alpha these days, they CAN have an alpha anyways.

As I have been painting for MSFS in the past and am not active in painting for MSFS>> for the last decade I cannot be absolutely sure about the centemporay bump-files in P3D
 

Last ten years I have been texturising models for X-Plane wich has quiet another type of file-structure.

Regards

 

Leen


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"Non licet omnibus volare cum aquilis" (Azzurro)

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Hi Leen.

Okay, thanks for the info. I'll do some further research to bring me up to current specs for FSX aircraft textures.

Regards...Ken.

 

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