# Revision history [back]

I believe you're looking for information on a model's geometry. First, let's understand the structure of a model in Gazebo.

• A model is a collection of links

• A link can contain several collisions

• Each collision has a shape. The shape can be something like a box, cylinder, sphere or a mesh.

So if you have a model which you know has a single link, which has a single collision, which is a sphere, you can get to its radius like this:

auto link = model->GetLink();


auto collision = link->GetCollisions()[0];

3. Collision::GetShape

auto sphereShape = boost::dynamic_pointer_cast<physics::SphereShape>(collision->GetShape());

auto radius = sphereShape->GetRadius();

• I couldn't find the GetCollisionBox function in Gazebo, where did you get it from?
• As for GetBoundingBox, it represents the world axis-aligned bounding box [1]. That is the smallest box aligned with the world which fully contains the model.