Help with making a skybox seamless

[Tormentor667]

Dear ZDoomers,

I am having a problem with a skybox texture currently, that's for Blade of Agony. The original skybox texture had resolution of 256x256 pixels and suffered a terrible jpg compression. So what I did was taking the skybox tiles and run them through an AI upscaler ("Gigapixel AI" to be more precise). The result was amazing, the jpg-artifacts were gone and the ai was able to recover clouds and mountains perfectly.

2020-11-15_183925.jpg

The problem now is, that the transitions between each single skybox tiles is not seamless anymore.

2020-11-15_184300.jpg

It mostly suffers at the top part where the walls meet the ceiling. I already thought about sticking all pieces of the cube together and run it once more through the upscaler, but that would only reduce the problem in 6 cases where the wall parts meet, and where one wall part meets the ceiling, so this is no solution.

What I would like to do is to edit the images in Photoshop and manually draw and repair the borders to make them seamless. But is there some kind of a plugin that can display a cube in Photoshop and let me draw the skybox tiles from the inside? Or does someone have a better idea on how to fix this?

Thanks kindly,
Torm

[Enjay]

I've done it myself a few times and, honestly, I found it pretty tricky because it's impossible to get all the sides that you want to smooth right next to each other at any one time.

I'm not aware of any plug ins, but then I don't use Photoshop - so there might be something. Being able to edit the graphics as part of an assembled cube would make things much easier.

My method for problems like the ones in your screenshot is to place the sky top in the middle of an image and arrange the sides around it, matching them to the edges that they are meant to be adjacent to (i.e. recreate a "net" of the images). Then I use blur/clone/whatever tools to make the transition smooth. Once I'm happy with the result, I cut the image up into its separate panels again.

What you've got to watch out for though, is what you do near the edges that are currently not sitting beside each other but which will later be stitched together by GZDoom. If you only want to edit where the tops and sides meet, try to work towards the upper corners of the side panels and avoid touching their edges if you can help it. It is very easy to accidentally change one of those edges and create a mis-matched edge too (so then you have to sit them beside each other in your editor and smooth that - making sure not to touch the upper edge where the sides meet the top this time). I've found myself chasing little errors like that all over the sky before.

So it is possible to do it manually, but it is sometimes a pain to do it.

[Tormentor667]

Hey Enjay, thanks kindly for your detailed explanation. I actually 'feared' that in the end the only way to do it is manually. It takes time, but it is doable to an extend that makes it look good. But as you said, it's a pain to do it and maybe someone has an idea how to solve it in a different, more comfortable way

[Rachael]

What I would do is
1) import them into Photoshop as smart objects (only 2 at a time)
2) rotate them as needed,
3) create a merged duplicate,
4) Use the smudge or blur tool or whatever you are going to do to smooth the edges
Then for each smart object layer:
5) Ctrl-click on the affected smart object layer, then select the smoothed composite,
6) and with the resulting marquee copy the smoothed work,
7) then open the smart object and paste it directly into the smart object
8) un-rotate the texture
9) export the result directly from inside the smart object file
10) do the same for the other

It's a bit time consuming but that's what I would do to make it easier on myself. I could probably smooth that thing out within an hour using this method.

[Tormentor667]

That sounds like a very good plan, I though about smartobjects myself already and I am happy to see that this idea is reasonable. I will try it

*EDIT*
Tried it, works pretty good that way and the result is perfect, took me about 15 minutes. Thanks to Enjay and Rachael for helping me with this.

[Rachael]

Glad that worked for you. 👍