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Skinning AO question

Discussion in 'Assetto Corsa Modding Discussions' started by Esotic, Jul 18, 2016.

  1. Esotic

    Esotic
    Premium Member

    Simple/stupid/noob question.

    Am I supposed to hide the Ambient Occlusion layer when exporting the dds files from Gimp/Photoshop for AC liveries? I've noticed if I leave it on I sometimes get unsightly banding in areas with solid colors, especially on side panels of cars like the mx5.

    Cheers,

    Dave/Esotic
     
  2. Benutzername

    Benutzername
    Online Martini Racing - Founder and driver

    I work with GIMP and always had problems when saving dds files. There always were some artefacts and banding somewhere.

    I just compress the file into one layer and copy that image into paint.net and save it with that program in dds. Everything works fine there.

    Might be that there is a different solution though
     
    • Like Like x 1
  3. Esotic

    Esotic
    Premium Member

    So you leave the AO on? And then Copy/Paste in windows after flattening the file? I'm wondering if maybe there's some way to increase the color bit depth to solve this problem.
     
  4. Benutzername

    Benutzername
    Online Martini Racing - Founder and driver

    Well the AO gives the skin more depth, it's meant to be on.
     
  5. Stereo

    Stereo
    Premium Member

    Color depth depends on dds format, DTX5 is 16 bit colour (5-6-5) and block compressed, and GIMP's dds filter is pretty bad by default in terms of dithering and colour-accuracy.
     
    Last edited: Jul 19, 2016
  6. Esotic

    Esotic
    Premium Member

    I'm hoping the JPG I attached properly conveys why I'm unhappy with the AO in the template. The YouTube vid shows the WIP skins, the solid color JPG is just for demonstration.

    The solid color DDS file was generated by exporting a PNG out of Photoshop (got tired of the PSD DDS plugin generating blank DDS files) and then converted through ImageMagick to the DDS (-define dds:compression=dxt5 -define dds:mipmaps=6). I'm starting to feel like the AO layer in the template is inherently noisy/crappy. Recreating it is currently beyond my abilities, so turning it off seems like a reasonable choice at this point. The skins do tend to look a bit bright, but I'm guessing I could just tone down the colors to compensate for no AO?

    All the skins in the vid were exported straight from Gimp to the DDS file with no AO:

    Sorry for the blocky vid, 34 AI cars is taxing my system and leaving none for the capture software. :)

    Thanks for all the feedback,

    Dave\Esotic
     

    Attached Files:

  7. Esotic

    Esotic
    Premium Member

    Actual skin close-up with no AO for comparisons sake attached.
     

    Attached Files:

  8. Blank .dds from photoshop? It`s the way to do this stuff properly.... If you can sort that little problem out, you`ll have no problems with skinning anything.

    Are you getting some sort of errors while exporting from PS?

    Chances are that it`s exporting a blank file as there`s no background layer in the template (a common problem with templates). The PS .dds exporter can struggle with exporting the file properly if it has an alpha channel and no proper background layer in the main layers panel.

    It`s always best practise to add one anyway, so just create a new standard layer in the layers panel, move it to the bottom of all other layers, fill it solid black or white (really doesn`t matter, but I do it anyway so I can see it`s the redundant background layer), then with that layer highlighted, go to the menu bar, select "Layer", then "New", then "Background From Layer".

    Exporting to .dds should work perfectly fine from then on, unless there is something else causing trouble.
     
    Last edited: Jul 19, 2016
    • Like Like x 1
  9. Esotic

    Esotic
    Premium Member

    @unseen Thanks for all the good suggestions. I'll try that when I get home this evening.

    Before flattening the layers in PS CS2 (on Windows 10) I was getting errors (unsupported input format?), once I flattened layers the export worked without error, but the DDS looked blank in the windows preview and failed to apply properly in AC (didn't get around to checking any .log files for error messages).

    I'm mostly curious to see what the differences will be when exporting very similar skins from PS and Gimp. I have a lot of python/autoit scripts that automate Gimp, imagemagick, and the copying/creation of files (windows level AutoIT macro for creating template based skin packs), so I'd mostly like to find a way to get that workflow optimized (if that's even possible). Doing some comparisons with what's being exported from PS CS2 will give me a good baseline for the quality I should expect my Gimp based toolchain to achieve.

    If Gimp totally fails me then I may have to reconsider using it in my toolchain. :(

    Cheers,

    Dave\Esotic
     
  10. Adding that background layer to your .psd files means you don`t have to go through the step of flattening it before exporting to .dds, which can save a lot of time if you`re constantly testing how it looks on a car.

    Really surprised CS2 works at all in win10. It could be dreadfully flaky in 7.
     
    • Like Like x 1
  11. Esotic

    Esotic
    Premium Member

    There's still some banding when I save the DDS from PS CS2 through the DDS plug-in, but it's better than Gimp. Still curious how to get rid of it completely. Thanks for the guidance. After adding the background layer I had to adjust the alpha layer, as it was set to a very dark grey, which made all the color barely visible. :)
    Showroom_ks_mazda_mx5_cup_20-6-2016-9-6-47.jpg
     
  12. Benutzername

    Benutzername
    Online Martini Racing - Founder and driver

    When i save it with paint.net and use the A8R8G8B8 setting while saving the .dds i dont get any bending. The file is quite huge with that method, though.
     
  13. Esotic

    Esotic
    Premium Member

    @Benutzername that totally works, and yes, the file is on the order or 20MBs as opposed to something more like 5MBs. All good information. I think I learned something today. :)
     
  14. Esotic

    Esotic
    Premium Member

    After some more research it looks like a layer of noise is my best option for turning this lemon into lemonade (or is that banding into band-aid?). I'll probably fine-tune the kind and amount of noise, but I have to assume this is the right direction. I made some noise, duplicated the layer, inverted the colors, flipped the duplicate horizontally, merged the noise layers together, then adjusted the blend amount. The original noise layer only appeared to darken the colors, as opposed to creating something like a "metallic sparkle" in both alpha directions (darker and lighter). This noise layer is sitting directly on top of the AO.
    Showroom_ks_mazda_mx5_cup_20-6-2016-13-12-19.jpg
     
  15. Stereo

    Stereo
    Premium Member

    Just went to look for the specific options in the GIMP DDS plugin and well, they've been removed from the plugin.

    http://registry.gimp.org/node/70
    Go here and install plugin version 2.0.2; 3.0.1 is the bad version (as far as banding in the AO).
    [​IMG]
    The export options you want are 'distance' (don't know what default is but it's garbage on gradients) and 'dithering'

    Or, better, just use Photoshop.
     
    • Like Like x 2
  16. Esotic

    Esotic
    Premium Member

    I just discovered that my gaming monitor at home (a 144hz TN panel) has 6 bit color, which really exacerbates the problem. When I make and test skins on a Surface® they look much better, but I'm still using some noise layers to break up the AO. When I get something finalized I'll try to remember and post it up here. I also try that 2.02 version of the DDS plug-in.
     
  17. Esotic

    Esotic
    Premium Member