Introductory

Isaac Sim Add Simple Objects

Showcase the basic GUI functions that add simple objects to the stage, as well as inspecting and modifying their physics and material properties

Learning Objectives

This tutorial details how to add simple primary shapes to the scene and edits their properties
Add and manipulate simple shapes
Enable physics properties in objects
Examine collision properties
Edit physics properties such as friction
Edit material properties such as color and reflectivity

Getting Started

Prerequisites
Complete Isaac Sim Interface and Environment Setup Tutorial

Adding Objects to the Scene

(1)Start by adding a Cube to the stage as the mobile robot’s body

Go to the Menu Bar
Click Create > Shapes > Cube
(2)Change the size of the cube

Select the Cube on the Stage tree > Go to the Property tab > Find Geometry > Size
For now type in 1.0
(3)Move it above the ground and change its shape by using the gizmos

Keep the property tab open for the cube
Movements by the gizmo are reflected in the object’s transform

Change Shape
(4)Directly type into the property window to make your changes

Fix the translation (Transform > translate) of the cuboid at (0, 0, 1), and the scale (Transform > Scale) at (2, 1, 0.5)
(5)Add cylinder and adjust the values

Add a cylinder to the stage
Click Create > Mesh > Cylinder

Change its Geometry > Radius to 0.5, and Geometry > Height to 1.0

Place it at y = 1.5 and z = 1.0, and rotate it around the x-axis by 90 degrees
(6)Duplicate the cylinder we just made

Right click it on the stage tree and Duplicate

Move it to y = -1.5 while keeping all other parameters the same

Adding Physics Properties

Objects added first are only visual objects, with no physics or collision properties attached to them
Problem: Simulation is started by pressing Play and gravity is applied. But if started, objects do not move
Why?: They are unaffected by physics
Solution: Turn them into rigid bodies with collision properties, as a robot should be
(1)Test by playing Play

(2)Select the Cube and both Cylinders on the stage tree by clicking while holding down the Ctrl + Shift key to select each object, or just Shift if they are consecutively listed on the tree

(3)Add physics
In the Property tab > Click on the + Add button

Select Physics > Rigid Body with Colliders Preset
(4)Press Play, and all three objects should now fall to the ground

Rigid Body with Colliders Preset”: Automatically add both Rigid Body API and Collision API to the objects
These two APIs can be applied separately
Can have objects that have mass and are affected by gravity but have no collision properties, so you can pass right through them
Can have objects you can run into but hang in the air and are not affected by gravity
Check which APIs the selected object has

Go to its Property tab > Scroll down to find sections labeled Rigid Body and Collider

Add the APIs separately (Under the same + Add button)

Remove APIs (Click on the X to delete the section)

Examine Collision Meshes

Need to visually examine the collision meshes for the objects
See the outlines of the collision meshes

Find the eye icon on top of the viewport > Click Show By Type > Physics > Colliders > All

Purple outlines should show up surrounding any objects that have collision APIs applied
Objects: cuboid, the cylinders, and the ground plane

Adding Contact and Friction Parameters

Modify frictional properties (1)First create a different physics material and then assign it to the desired object

Go to the Menu Bar
Click Create > Physics > Physics Material
Select Rigid Body Material in the popup box

->New PhysicsMaterial will appear on the stage tree

Material Properties

Objects may reflect the color of the spotlight we’ve added earlier, but it doesn’t actually have any colors assigned
Confirm it by turning off the spotlight
Change the color of the object
(1)Create a different material and then assign it to the objects, just like with the physics materials
Create two, one for the body of the car and one for the wheels

Click Create > Materials > OmniPBR twice
(2)Rename materials

Right-click on the newly added materials on the stage tree > Rename them to body and wheel
Assign the corresponding rigid bodies to the newly created materials

Go to the Materials on selected models item in its Property tab > Select the matching material from the dropdown box

cube

cylinder & cylinder01

Change the property of the new materials
Select one of them on the stage tree
body

wheel

Change its base color in Material and Shader/Albedo and play with its reflectivity roughness and whatever else you find interesting
You should see the color of the corresponding parts on the car change accordingly

Summary

Explained how to add and manipulate object properties in the GUI
Topics Covered
(1)Adding primitive shapes onto the Stage
(2)Editing material properties, physics properties, and collision properties

Reference:
https://docs.omniverse.nvidia.com/isaacsim/latest/gui_tutorials/tutorial_intro_simple_objects.html#isaac-sim-app-tutorial-intro-simple-objects