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Creating Visualization Markers

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Visualization markers are useful to debug the state of the environment. They can be used to visualize the frames, commands, and other information in the simulation.

While Isaac Sim provides its own isaacsim.util.debug_draw extension, it is limited to rendering only points, lines and splines. For cases, where you need to render more complex shapes, you can use the markers.VisualizationMarkers class.

This guide is accompanied by a sample script markers.py in the IsaacLab/scripts/demos directory.

# Copyright (c) 2022-2025, The Isaac Lab Project Developers (https://github.com/isaac-sim/IsaacLab/blob/main/CONTRIBUTORS.md).
# All rights reserved.
#
# SPDX-License-Identifier: BSD-3-Clause
"""This script demonstrates different types of markers.
~~~bash
# Usage
./isaaclab.sh -p scripts/demos/markers.py
~~~
"""
"""Launch Isaac Sim Simulator first."""
import argparse
from isaaclab.app import AppLauncher
# add argparse arguments
parser = argparse.ArgumentParser(description="This script demonstrates different types of markers.")
# append AppLauncher cli args
AppLauncher.add_app_launcher_args(parser)
# parse the arguments
args_cli = parser.parse_args()
# launch omniverse app
app_launcher = AppLauncher(args_cli)
simulation_app = app_launcher.app
"""Rest everything follows."""
import torch
import isaaclab.sim as sim_utils
from isaaclab.markers import VisualizationMarkers, VisualizationMarkersCfg
from isaaclab.sim import SimulationContext
from isaaclab.utils.assets import ISAAC_NUCLEUS_DIR, ISAACLAB_NUCLEUS_DIR
from isaaclab.utils.math import quat_from_angle_axis
def define_markers() -> VisualizationMarkers:
"""Define markers with various different shapes."""
marker_cfg = VisualizationMarkersCfg(
prim_path="/Visuals/myMarkers",
markers={
"frame": sim_utils.UsdFileCfg(
usd_path=f"{ISAAC_NUCLEUS_DIR}/Props/UIElements/frame_prim.usd",
scale=(0.5, 0.5, 0.5),
),
"arrow_x": sim_utils.UsdFileCfg(
usd_path=f"{ISAAC_NUCLEUS_DIR}/Props/UIElements/arrow_x.usd",
scale=(1.0, 0.5, 0.5),
visual_material=sim_utils.PreviewSurfaceCfg(diffuse_color=(0.0, 1.0, 1.0)),
),
"cube": sim_utils.CuboidCfg(
size=(1.0, 1.0, 1.0),
visual_material=sim_utils.PreviewSurfaceCfg(diffuse_color=(1.0, 0.0, 0.0)),
),
"sphere": sim_utils.SphereCfg(
radius=0.5,
visual_material=sim_utils.PreviewSurfaceCfg(diffuse_color=(0.0, 1.0, 0.0)),
),
"cylinder": sim_utils.CylinderCfg(
radius=0.5,
height=1.0,
visual_material=sim_utils.PreviewSurfaceCfg(diffuse_color=(0.0, 0.0, 1.0)),
),
"cone": sim_utils.ConeCfg(
radius=0.5,
height=1.0,
visual_material=sim_utils.PreviewSurfaceCfg(diffuse_color=(1.0, 1.0, 0.0)),
),
"mesh": sim_utils.UsdFileCfg(
usd_path=f"{ISAAC_NUCLEUS_DIR}/Props/Blocks/DexCube/dex_cube_instanceable.usd",
scale=(10.0, 10.0, 10.0),
),
"mesh_recolored": sim_utils.UsdFileCfg(
usd_path=f"{ISAAC_NUCLEUS_DIR}/Props/Blocks/DexCube/dex_cube_instanceable.usd",
scale=(10.0, 10.0, 10.0),
visual_material=sim_utils.PreviewSurfaceCfg(diffuse_color=(1.0, 0.25, 0.0)),
),
"robot_mesh": sim_utils.UsdFileCfg(
usd_path=f"{ISAACLAB_NUCLEUS_DIR}/Robots/ANYbotics/ANYmal-C/anymal_c.usd",
scale=(2.0, 2.0, 2.0),
visual_material=sim_utils.GlassMdlCfg(glass_color=(0.0, 0.1, 0.0)),
),
},
)
return VisualizationMarkers(marker_cfg)
def main():
"""Main function."""
# Load kit helper
sim_cfg = sim_utils.SimulationCfg(dt=0.01, device=args_cli.device)
sim = SimulationContext(sim_cfg)
# Set main camera
sim.set_camera_view([0.0, 18.0, 12.0], [0.0, 3.0, 0.0])
# Spawn things into stage
# Lights
cfg = sim_utils.DomeLightCfg(intensity=3000.0, color=(0.75, 0.75, 0.75))
cfg.func("/World/Light", cfg)
# create markers
my_visualizer = define_markers()
# define a grid of positions where the markers should be placed
num_markers_per_type = 5
grid_spacing = 2.0
# Calculate the half-width and half-height
half_width = (num_markers_per_type - 1) / 2.0
half_height = (my_visualizer.num_prototypes - 1) / 2.0
# Create the x and y ranges centered around the origin
x_range = torch.arange(-half_width * grid_spacing, (half_width + 1) * grid_spacing, grid_spacing)
y_range = torch.arange(-half_height * grid_spacing, (half_height + 1) * grid_spacing, grid_spacing)
# Create the grid
x_grid, y_grid = torch.meshgrid(x_range, y_range, indexing="ij")
x_grid = x_grid.reshape(-1)
y_grid = y_grid.reshape(-1)
z_grid = torch.zeros_like(x_grid)
# marker locations
marker_locations = torch.stack([x_grid, y_grid, z_grid], dim=1)
marker_indices = torch.arange(my_visualizer.num_prototypes).repeat(num_markers_per_type)
# Play the simulator
sim.reset()
# Now we are ready!
print("[INFO]: Setup complete...")
# Yaw angle
yaw = torch.zeros_like(marker_locations[:, 0])
# Simulate physics
while simulation_app.is_running():
# rotate the markers around the z-axis for visualization
marker_orientations = quat_from_angle_axis(yaw, torch.tensor([0.0, 0.0, 1.0]))
# visualize
my_visualizer.visualize(marker_locations, marker_orientations, marker_indices=marker_indices)
# roll corresponding indices to show how marker prototype can be changed
if yaw[0].item() % (0.5 * torch.pi) < 0.01:
marker_indices = torch.roll(marker_indices, 1)
# perform step
sim.step()
# increment yaw
yaw += 0.01
if __name__ == "__main__":
# run the main function
main()
# close sim app
simulation_app.close()

Configuring the markers

The ~markers.VisualizationMarkersCfg class provides a simple interface to configure different types of markers. It takes in the following parameters:

  • markers.VisualizationMarkersCfg.prim_path: The corresponding prim path for the marker class.
  • markers.VisualizationMarkersCfg.markers: A dictionary specifying the different marker prototypes handled by the class. The key is the name of the marker prototype and the value is its spawn configuration.

In case the marker prototype specifies a configuration with physics properties, these are removed. This is because the markers are not meant to be simulated.

Here we show all the different types of markers that can be configured. These range from simple shapes like cones and spheres to more complex geometries like a frame or arrows. The marker prototypes can also be configured from USD files.

marker_cfg = VisualizationMarkersCfg(
prim_path="/Visuals/myMarkers",
markers={
"frame": sim_utils.UsdFileCfg(
usd_path=f"{ISAAC_NUCLEUS_DIR}/Props/UIElements/frame_prim.usd",
scale=(0.5, 0.5, 0.5),
),
"arrow_x": sim_utils.UsdFileCfg(
usd_path=f"{ISAAC_NUCLEUS_DIR}/Props/UIElements/arrow_x.usd",
scale=(1.0, 0.5, 0.5),
visual_material=sim_utils.PreviewSurfaceCfg(diffuse_color=(0.0, 1.0, 1.0)),
),
"cube": sim_utils.CuboidCfg(
size=(1.0, 1.0, 1.0),
visual_material=sim_utils.PreviewSurfaceCfg(diffuse_color=(1.0, 0.0, 0.0)),
),
"sphere": sim_utils.SphereCfg(
radius=0.5,
visual_material=sim_utils.PreviewSurfaceCfg(diffuse_color=(0.0, 1.0, 0.0)),
),
"cylinder": sim_utils.CylinderCfg(
radius=0.5,
height=1.0,
visual_material=sim_utils.PreviewSurfaceCfg(diffuse_color=(0.0, 0.0, 1.0)),
),
"cone": sim_utils.ConeCfg(
radius=0.5,
height=1.0,
visual_material=sim_utils.PreviewSurfaceCfg(diffuse_color=(1.0, 1.0, 0.0)),
),
"mesh": sim_utils.UsdFileCfg(
usd_path=f"{ISAAC_NUCLEUS_DIR}/Props/Blocks/DexCube/dex_cube_instanceable.usd",
scale=(10.0, 10.0, 10.0),
),
"mesh_recolored": sim_utils.UsdFileCfg(
usd_path=f"{ISAAC_NUCLEUS_DIR}/Props/Blocks/DexCube/dex_cube_instanceable.usd",
scale=(10.0, 10.0, 10.0),
visual_material=sim_utils.PreviewSurfaceCfg(diffuse_color=(1.0, 0.25, 0.0)),
),
"robot_mesh": sim_utils.UsdFileCfg(
usd_path=f"{ISAACLAB_NUCLEUS_DIR}/Robots/ANYbotics/ANYmal-C/anymal_c.usd",
scale=(2.0, 2.0, 2.0),
visual_material=sim_utils.GlassMdlCfg(glass_color=(0.0, 0.1, 0.0)),
),
},
)

Drawing the markers

To draw the markers, we call the ~markers.VisualizationMarkers.visualize method. This method takes in as arguments the pose of the markers and the corresponding marker prototypes to draw.

while simulation_app.is_running():
# rotate the markers around the z-axis for visualization
marker_orientations = quat_from_angle_axis(yaw, torch.tensor([0.0, 0.0, 1.0]))
# visualize
my_visualizer.visualize(marker_locations, marker_orientations, marker_indices=marker_indices)
# roll corresponding indices to show how marker prototype can be changed
if yaw[0].item() % (0.5 * torch.pi) < 0.01:

Executing the Script

To run the accompanying script, execute the following command:

./isaaclab.sh -p scripts/demos/markers.py

The simulation should start, and you can observe the different types of markers arranged in a grid pattern. The markers will rotating around their respective axes. Additionally every few rotations, they will roll forward on the grid.

To stop the simulation, close the window, or use Ctrl+C in the terminal.