What method is this for creating textures? (Game design related)

[Easton777]

I need to try to copy the workflow as based off this picture:

It is an older version of PS but I think the process is still the same. Essentially I would model a parking lot and road in a 3d program, UV unwrap it in say 10x10 meter chunks, then add textures to it in PS as this person has in the picture with the grid. What is the blue grid? I would think it is his UVs from the 3d program tiled in a specified unit of measurement.

How would this grid be laid out and textures added to them?

Sorry for not being more specific, I am not yet experienced enough with PS, all I know is that based off of this picture is the same workflow that I would have to follow.

Edit: Here is the video this is from:

Orbx EGTR Elstree airport - YouTube

If anyone experienced in Photoshop can explain to me what it looks like this guy did and how he did it I would greatly appreciate it.

[rayek.elfin]

That tool is the Slice tool. It allows you to slice up a design in chunks, and export all the chunks separately in one go.

Tutorial (for web pages; the workflow is identical): How to Use the Slice Tool in Photoshop - YouTube

[Easton777]

But how would you make it In a perfect grid?

And what exactly does this do for something like this?   

Edit: I found out how to make it into a grid, but why would this method be used for something like what is seen in the video?

[rayek.elfin]

Looking at that VERY high resolution of the map example, I believe each map part is an exact 1024/2048/4096/8096 pixel wide and high texture that is loaded up later in the game engine. You can't load up the entire map at once: it would kill the video chip's ram, in particular when other textures must be loaded up as well, so each part is loaded up when needed at run-time.

At least, that is what I would do, and what I can make from this example.

[rayek.elfin]

Just watched the video. Okay, so that's MS Flight sim - yeah, makes sense to split it up into separate parts. Parts far away can be rendered at lower resolution this way. And most lower-grade video chips generally cannot handle larger textures than 2048px, or perhaps 4096px in 3d. For example, the 750m can't handle more than 2048px. A modern one like 1080 gtx can handle 16384px ones, but even that wouldn't suffice to handle that example map. So textures are split up in chunks and mapped on geometry.

[Easton777]

I am still not quite sure where the slicing comes in though. I saw that in the modeling software he created a grid of polys, but why the slicing? I thought that was just for photography and web design. I thought UV unwrapping was just for the say 4096x4096 pixel maps, how does the slicing play into this exactly? So would the slices be 4096x 4096 or the UV Map, because in the modeling software you'd have to unwrap the area then bring it into PS, but here it looks like the guy took some satellite imagery and just painted using the slices...I'm so confused about this