Uniform Terrains

A uniform terrain is one continuous walkable surface, rather than a grid of tiles. Use it when the ground should be a single condition held constant across the whole course: level, a fixed grade, or a rough surface without a specific layout. This is the terrain family for steady-state locomotion, and the one the reflex CO pipeline is designed around.

Select it with a top-level "terrain" string. That key is what distinguishes the two config forms, so a uniform config never carries grid or tiles:

{ "msk": "myolegs22", "device": "Humotech_L1", "terrain": { "terrain": "slope", "deg": 8 } }

The four types

terrain	Surface	Geometry
"flat"	Level ground	One effectively infinite plane
"slope"	A constant grade	One tilted plane, rising in +x
"random"	Rough ground	One heightfield of per-cell noise
"sinusoidal"	Rolling waves	One heightfield, a sinusoid along +x

flat and slope are planes, so they extend as far as the model can walk. random and sinusoidal are heightfields covering extent x extent meters, with a smooth safe zone flattened around the origin so a model does not spawn on a bump or in a pit.

Every field

Only terrain is required. Everything else has a default, and a field that does not apply to the chosen type is ignored.

Key	Default	Applies to	Meaning
terrain	required	all	"flat", "slope", "random" or "sinusoidal".
terrain_name	"uniform_<terrain>"	all	Output name. Must be a bare file name, since it becomes terrain/<terrain_name>.xml.
deg	0.0	slope	Grade in degrees, -90 < deg < 90. Positive rises in +x, the walking direction.
amplitude	0.1	random, sinusoidal	Surface relief in meters. Must be greater than 0.
period	1.0	sinusoidal	Wavelength along +x in meters. Must be greater than 0.
seed	0	random	RNG seed, so a rough surface is reproducible.
extent	20.0	random, sinusoidal	Full side length of the surface in meters.
resolution	256	random, sinusoidal	Heightfield grid resolution, same in both axes. Minimum 8.
safe_zone_radius	3.0	random, sinusoidal	Radius in meters over which the surface is flattened toward 0 around the origin. 0 disables it.
base_depth	1.0	random, sinusoidal	Solid thickness below the surface in meters.
palette_preset	"uniform"	all	"diverse", "uniform" or "custom".
palette	{}	all	Surface rgba, under the key "uniform", "terrain", or the terrain type name.
texture	none	all	A texture block, as described in Configuration.

Choosing resolution and extent together

These two set the cell size, and the cell size is what the surface actually feels like underfoot. random is noise at cell scale: neighbouring samples differ by up to amplitude, so the cell size sets the wavelength of the roughness.

At the defaults, extent = 20 over resolution = 256 gives cells of about 8 cm. That is fine-grained rubble. For longer-wavelength undulation at the same relief, raise extent or lower resolution:

{ "terrain": "random", "amplitude": 0.08, "extent": 20.0, "resolution": 64 }

which gives roughly 32 cm cells. sinusoidal is smooth, so its shape comes from period and resolution only needs to be fine enough to resolve it.

Typos are rejected

Unknown keys are errors. This is worth stating plainly, because the failure it replaces was silent:

{ "terrain": "slope", "dge": 8 }

used to build flat ground and pass validation, so a run completed and reported numbers for a grade that was never there. It now fails with the offending key named. Prefix a key with _ if you want to keep it as a comment.

Asking where the ground is

A uniform surface still answers the surface-height queries, so the same code works whether the terrain is uniform or tiled:

from myoassist_terrains import surface_height_at

z = surface_height_at(config, x=4.0, y=0.0)   # on an 8 degree slope: about 0.56

See Configuration for the footprint variant and why this is preferable to measuring a compiled model.

Velocity maps are the one thing that needs a tiled terrain: they sample per cell, and a uniform surface has no cells. Passing one is rejected with a message saying so.