Imported Maps are blurred?

[Igameart]

My imported maps appear to be gaussian blurred after loading into HTerrain, both the heightmap and the splatmap.

Here is a terrain in blender:

This is the same terrain in Godot after importing the exported height and splatmaps:

A portion of the splatmap:

I am using Godot 4.1.1
Using the version of HTerrain found in the AssetLib as of this week,
Windows 11
RTX 3050
Forward+ renderer.

[Zylann]

Assuming resolution hasn't changed between Blender and Godot, I don't know what's up here. The plugin doesn't do any blurring. The only "blurring" is the normal linear interpolation done by the shader when it reads the textures, and yet for the heightmap sampling happens at pixel centers. Eventually there will be some degree of pixel conversion depending on the format you exported the textures with. The heightmap looks fine, outside very minor differences.

There will be some differences because it's very likely the way it is rendered in Blender and Godot differs. Shaders have different options. The plugin also uses a geometry pattern that's likely different than the one you used in Blender (check wireframe).

Which shader are you using? Which resolution are your heightmap and splatmap when exported from Blender? Do you have a test project I can reproduce this issue in, with the original heightmap and splatmap to import and compare? (btw your splatmap has a lot of yellow in it, means there are areas where two textures from R and G will show at 50%/50% opacity at the same time; I also assume you omitted the alpha channel when you posted it?).
I can't really tell what is happening here. You can try checking the splatmap in lookdev mode, or tinker with the terrain shader maybe...

[lorddevereux]

I have been battling with understand this sort of problem - and so I offer the following observations in case they help. Part of this I think is due to weird or niggly differences in Godot 4 so the documentation needs a bit of adjustment.

I'm using

• Multisplat16_lite as I don't have bump/normal/etc maps
• 12 textures
• Resolution of everything is 512x512 (packed texture map is 2048x2048)

Maybe some of these things are obvious to people used to game dev, but they weren't to me!

• First, make sure your pixel values in your splatmap add up to a TOTAL of 255 each pixel. If you have more than one splatmap, make sure that the total of ALL the splatmaps for a given pixel adds up to 255. If it's more, weird things happen and the blending isn't right. I do this in Python using Pillow to normalise all my splatmaps.
• When using a manually created TextureArray (i.e. packing the textures in an image editor/via external tools), in the importer, TextureArray no longer exists in Godot4. You need to use Texture2DArray, and then change the type to VRAM Compressed, and tick Generate MipMaps. Otherwise, you get unknown RID errors

I now have my data set mostly working properly. The lack of trilinear blending in Multisplat16 (seems to also be a documented limit of Texture2DArray in Godot 4) makes the tiling a bit blocky, but I think I can get around that by increasing the splatmap resolution and applying a slight blur to smooth harsh texture changes.

Looking at the OP issue, is it possible that the shader is simply applying a "smooth" kind of normal shading rather than "flat", therefore rounding off the heightmap peaks?

[Zylann]

About splatmaps:

If you're using multisplat, importing splatmaps is going to be a bit different, I'm not even sure the plugin has an option to import more than one splatmap. How did you import them in? I guess you can do so by doing what you described, normalizing all weights across all splatmaps and save them as PNGs over those generated by the plugin in your terrain directory.
Some extra things to consider:

• Make sure each splatmap uses all RGBA channels, without destroying RGB when alpha channel is zero, like many image editors like to do as an "optimization" (and rarely have the option not to). It's a very common behavior but shading is one of the specific cases where you don't want this to happen.
• Make sure that splatmaps are NOT VRAM-compressed, because that typically causes blockyness. That should be the default as generated by the plugin, but who knows, I had issues reported in the past where users had somehow messed up those settings

About ground textures:

The lack of trilinear blending in Multisplat16 (seems to also be a documented limit of Texture2DArray in Godot 4) makes the tiling a bit blocky,

I'm not aware of such a limitation. Where did you see this? The plugin's shader does use linear filtering when sampling texture arrays. What the doc might say is that filtering will not work when sampling across two different layers of the array (Z axis), which is normal and isn't a problem for terrain rendering. Filtering should work fine on XY axis (since textures are 2D).
Also the fact you enabled VRAM-compression on these might make them look a bit blocky too, but that's usually not noticeable.

About the heightmap:

Looking at the OP issue, is it possible that the shader is simply applying a "smooth" kind of normal shading rather than "flat", therefore rounding off the heightmap peaks?

The heightmap sampler uses default bilinear filtering, however it samples it the middle of each pixel:

godot_heightmap_plugin/addons/zylann.hterrain/shaders/multisplat16_lite.gdshader

Line 162 in 222b4ab

cell_coords += vec2(0.5);

Therefore it does not smooth anything when it comes to vertex displacement.
You could try changing it to do no filtering at all by replacing the heightmap uniform with uniform sampler2D u_terrain_heightmap : filter_nearest;, but I doubt it will change anything.

Some possible causes that come to mind:

• You exported your heightmap in a format that looses precision, like 8-bit PNG, causing heights to be slightly rounded up
• Tiny differences can show up due to the wireframe pattern used by the plugin, which is likely different from what you had in Blender (you can check in the "Perspective" viewport menu in Godot)

[lorddevereux]

For the splatmaps - I imported the first one which created splat.png, then I copied the others to splat2, splat3, splat4.png and it works perfectly.

Make sure that splatmaps are NOT VRAM-compressed,

Thank you, that fixed it! I suppose I assumed that because the texture map was VRAM compressed, the splatmaps should be as well. I think that was the default though, but perhaps Godot set it like that because I added them to the project manually.

I'm using Python/Pillow to generate all the images here (from binary datasets) and that does (correctly) preserve all channels when in RGBA mode.

I'm not aware of such a limitation. Where did you see this?
According to this: https://docs.godotengine.org/en/stable/classes/class_texture2darray.html#class-texture2darray. The statement was not present in the Godot 3 documentation on TextureArray. However, you may be right, it might only be Z axis.

Sorry for slightly hijacking the post. I'm happy to share the Python code I used to normalise the splatmaps if that's helpful. Thanks again.