Cut off piece of terrain that is too big

So I have been looking around on how to cut off pieces of terrain from a map that got too big. I only needed the length from top left to bottom right corner and about half the width so there were a lot of extra at the sides that I didn’t need.

After looking around I didn’t find anything other than resize or split into smaller pieces. Neither of these would work since, again, the map is corner to corner.

What I did find though was, when the terrain is, essentially, only a plane with no highs on, I could use the “Paint Hole” tool to remove large chunks off my map and only leave the part that I need.

I don’t know right now if this is a good idea and I’m going to run into issues later, but the map is only the size that I need.

I found a bunch of old post about this that didn’t have a proper solution, so I thought that I should leave this post just in case someone else has the same problem. I’m sure someone who knows better than me can say if this is a good idea or not.

Personally, I can’t really see why it would be a problem since you can make other shapes with both the terrains and other objects just fine and especially when the “holes” are outside the view of the player. I would guess that it just makes for less data to render.

You can certainly do this to hide parts of the terrain that you don’t need, but if you do it to reduce rendering load/improve performance, I don’t think that’s how it works. “Paint Holes” doesn’t remove any geometry from the terrain, it just makes parts of it transparent, similar to a cutout shader. If these parts of the terrain are not visible, it won’t make any difference. And flat terrain is automatically optimized by Unity to use very few triangles.

But how would that work? If it only hides the terrain, would it not only hide it when you dig out from hills? Apparently you can make caves with it, so wouldn’t there be an invisible wall then if it only hides it or is it only hiding the bottom layer?

Also, why does the highlight around the terrain change when you paint holes in it?

But basically, having a big terrain that is not being used doesn’t matter much except looking really wierd for the person making the map. It’s kind of stupid though that the question about cutting off excessive terrain has been asked for fifteen years and there has never been an update that lets you make a custom terrain shape.

I’m not sure what exactly you mean, but it does affect the terrain collider, so that things can move through, but in a sense, there still is an invisible wall. And you can only make caves with it if you use meshes that cover up the hole: Digging into Terrain Paint Holes in Unity 2019.3

Maybe it was changed in a newer version (I can’t check right now, but as far as I know, the Terrain system hasn’t really changed a lot in the last few years), but for me the outline clearly shows the invisible terrain where a hole is. You can also change the shading mode to “Wireframe” or “Shaded Wireframe” to see the actual geometry of the terrain, including the areas with holes.

Well, it would be kind of impractical and not really bring any benefits over the square terrains we have. First of all, terrain can be expanded by creating neighboring tiles that blend nicely at the borders, which is only possible with squares. Secondly, texture layers and terrain details like grass use textures called splat maps, which are, you guessed it, square. Thirdly, as I wrote before, areas of low detail are automatically optimized to use as few triangles as possible. And lastly, Unity itself already renders terrain in smaller chunks and automatically culls parts that are outside the camera view.

Oh, ok, I understand.