As a Roblox Developer, the Terrain Tool is among one of the most neglected and worst tools available to Roblox Developers, it’s miserable to use and makes you want to bash your desk every time you even attempt to work with the system in place for Terrain.
Terrain voxel size
The current (4 by 4 studs size?) voxel system is a nightmare to work with, every single time you attempt to detail any of your Terrain or have control over smaller details it throws large uneven blobs everywhere, I’ve spent over an hour trying to make a small mud path on the edges of this road, I’d argue it’s an impossible task with these tools right now.
Brought up on multiple occasions: Remove the size limit to the Terrain Region tool
and More customization for Smooth Terrain
Smoothing Tool
If your terrain is only a single voxel thick it will make a massive hole in your terrain if you use the smoothing tool on the Terrain, this has been a nightmare as I’m trying to make flat terrain so vehicles and parts can easily be placed on top of the terrain with a smooth flow. Smoothing might as well be a slower Erode tool, it doesn’t smoothen anything, just makes deep holes in the terrain you’re trying to work with, it’s very frustrating.
Snapping
Developers should be given the ability to enable/disable the snapping with the whole variety of different Terrain Editing options. If I want to add terrain to make a slope or ramp I have to click move my camera, click again and so on forcing my workflow to be interrupted. Sometimes I just want to freely place without being restricted to a snapping grid.
Click and create a 'line’
If Developers were able to click and draw a line (e.g. a straight or curved line) and then the terrain would be placed along/as close as possible to the given line. This would be useful for the add/remove tool if you’re trying to quickly place a straight line of Terrain or something like that.
Region selection
Adding the ability to click and drag your cursor to select an area of terrain to apply a tool would be amazing, currently trying to make flat terrain is a nightmare, with this you could simply click and drag a box as which is seen as a ‘blueprint’ or selection box whilst you’re adding it, let go then click and drag to raise your terrain vertically, you can left-click one more time to confirm the placement or right-click to cancel placement at any point. The boxes would follow the snapping grid but possibly if the user’s camera is rotated it could select Terrain and work on a 15, 30 and 45 (so on) degree angle like the snapping tool for the ‘add’ tool.
A larger variety of pre-set brush shapes
The same as parts, there should be the introduction of a Cone, Cylinder (would be limited/only shown at a larger map size as you couldn’t make a cylinder with only a small amount of voxels).
Roughness/wear tool
This would do the opposite of smoothing, it would chip away at the Terrain and damage it like rain and acid does on real-world stone and other things. Developers could scale the harshness of the tool to allow them the most customization and freedom for their landscape.
Terrain Generation
If Developers were given a feature to click and place code-generated; hills, mountains, etc based on their own set of settings it would drastically increase workflow and make Developers lives significantly easier.
The settings would include:
- Height (can set variables for it to be randomized between)
- Area for the terrain to cover (X,Y)
- Harshness/Roughness (if the terrain would be really rough or smooth)
Brush Size
The current brush size bar and strength bar are awful, there should be a visual indication of the size across the bar as well as being able to directly type in the size like you’re able to do for Increment and Rotation.
It would be really awesome if Developers were given the ability to press a hotkey to resize their brush and movement of your cursor increases/decreases the value. This would make workflow significantly more streamlined. See Blender’s really awesome brush size feature by pressing F in painting mode.
https://gyazo.com/ce856debfa19d1d76c8c23d4718afc6a.gif
The ability to add a randomized strength between two set variables would be a really nice addition, this could add to the randomization and make Terrain look more realistic with natural elevation and deelivation across the landscape.
Move Terrain colour settings to the Terrain Editor interface
Painting tool
I strongly believe Roblox should give Developers the ability to select an area using the Terrain Tool (see below for how you would handle the selection of horizontal and vertical box) which will be replaced with your chosen paint material.
(I’m unsure if this possible at all) It would be absolutely amazing if Developers were able to click in Workspace on Terrain and all connected terrain of the same material would be replaced with that material, if there is a different material dividing the terrain it wouldn’t affect the non-connected terrain.
Pre-made Terrain Brush (saving/loading)
Either users or Roblox themselves should be allowed to package up the terrain and save them, then freely brush them wherever they like, this would be an amazing feature and would allow me to make a variety of different mountains, lakes and brush (either single click placement or repetitive placement at a timed interval as you hold down left click) them across my maps with ease.
For a demonstration, check out a similar plugin I use for parts, meshes and pre-made models: Brushtool 2.1 - Roblox
Other features which should be considered:
Control over terrain LOD (Level of Detail):
Note: I attempted to add polls to the thread but kept having a bug with polls pop up that wouldn’t allow me to add that many with ‘the same name’. Sorry 
