16-Bit raw greyscale map seems to be importing with reduced precision

[DingboDingboDingbo]

Describe the bug
A heightmap was cobbled together in GIMP, with bit depth set to 16 bit and color mode to greyscale. Exported as raw with default options. Built a simple test program in C++ to verify the export, everything appears normal. Upon importing the raw image as a heightmap for terrain, only a few (3-4?) different heights can be observed. When the png version of the same heightmap is imported (albeit at a lower bit depth), the terrain appears much smoother overall, (although still jagged due to the insufficient precision).

To Reproduce
Steps to reproduce the behavior:

1. Create a new HTerrain
2. Select it
3. Click on "Terrain" and import the heightmap (any min/max height values, I used 0,100)
4. Observe "low precision" terrain. Scale vertically to exaggerate stepping.

Expected behavior
The raw 16-bit heightmap should produce a significantly higher fidelity than the 8-bit png heightmap.

Screenshots
(png version):

(raw version)

Environment

• OS: Tested on Windows 10 and Manjaro
• Graphics card: Nvidia RTX 2080ti
• Godot version: 3.2.stable.mono.official
• Plugin version: 1.2.1
• Renderer used: GLES3

Contents of attached heightmaps.zip:
world8bit.png - the png file mentioned above - directly converted from the raw file via custom program to make sure the GIMP output was correct.
world.raw - the 16-bit uncompressed raw heightmap exported from GIMP.

heightmaps.zip

[Zylann]

My first guess is that Gimp exported the data in a different endianess than what the plugin reads... but I'll need to take a closer look

[Zylann]

I was able to obtain a non-flat terrain by swapping endianess. The fact Gimp does not indicate this doesn't help^^"
But the result still shows very similar to the PNG result. Maybe your raw file really is 16-bit, but the tool you used inside Gimp might not have worked using those 16-bits of precision?
You could try exporting as EXR to see if that works.

When I import a 16-bit raw heightmap generated by the Scape terrain generator, I get smooth results.

I changed tag to enhancement because the import dialog needs an option to choose endianess.

[DingboDingboDingbo]

I was about to report the same findings after swapping the endianess. I'll investigate the Gimp situation further, but I doubt that it'll be relevant here! Thank you for your time and hard work on this plugin!

[RonanZe]

If you search for an immediat solution, I was able to export and import a perfect matching heightmap from blender by using EXR in float (32bits), then, convert it in Krita in the format "R32 Heightmap".

Then I had to change the code of the plug a little bit to support the R32 format.

If I remember well, I had to change the following points in the hterrain_data.gd script:

1. FORMAT_RH to FORMAT_RF in hterrain_data.gd
   

   godot_heightmap_plugin/addons/zylann.hterrain/hterrain_data.gd

   Line 29 in 1cdd66b

   Image.FORMAT_RH, # height

2. in the "func _import_heightmap" the ext "raw" to "r32" and the loop that read the data from "var gs = float(f.get_16()) / 65535.0" to "var gs = f.get_float()" because the R32 work in float and raw in integer.
   

   godot_heightmap_plugin/addons/zylann.hterrain/hterrain_data.gd

   Line 1217 in 1cdd66b

   elif ext == "raw":

   
   

   godot_heightmap_plugin/addons/zylann.hterrain/hterrain_data.gd

   Line 1258 in 1cdd66b

   var gs = float(f.get_16()) / 65535.0

3. change "var file_res = Util.integer_square_root(file_len / 2)" to var file_res = Util.integer_square_root(file_len / 4)
   

   godot_heightmap_plugin/addons/zylann.hterrain/hterrain_data.gd

   Line 1227 in 1cdd66b

   var file_res = Util.integer_square_root(file_len / 2)

I was thinking to make a patch but I'm not skilled enough with Git and Github :)

[Zylann]

Added an endianess option in beb4502

[DingboDingboDingbo]

I've confirmed that Gimp's raw export will output a 16 bit file, but the actual values are converted to 8 bit during the process, which is pretty silly.

I hope you don't mind my leaving this comment here in case someone else stumbles across a similar issue!