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Questions to SDF, urdf, xacro, material, textures using Gazebo

asked 2017-03-23 06:43:56 -0600

updated 2017-03-24 08:29:55 -0600

Hi Guys,

Currently I am a little stuck with my xacro model.

I have a texture file which should be attached to a surface in the xacro. How to add materials to your package, what do I need to export (what could I export) in the package.xml

Where do I really find the stuff documenting this features.



I have seen that for url there can be file and model. Does package also work here? What are those replaced with in the end and which of these exist?

Next: in the material file:

 material a/mat
      ambient 0.5 0.5 0.5 1.0
      diffuse 1.0 1.0 1.0 1.0
      specular 0.0 0.0 0.0 1.0 0.5

        texture file.png
        filtering trilinear

From where and how does it know where file.png is?

Does it just go standard for "../textures" ?

Folder structure is mostly like

  • package
    • models
      • myModel
        • textures
        • scripts

It works for me in a sdf file, but it seems to work never in my xacro.

Somehow this is related to the package.xml as well where you export model or media path I found as well:

  <gazebo_ros gazebo_media_path="${prefix}"/> 


  <gazebo_ros gazebo_model_path="${prefix}/models"/> 

Are there any others and what exactly do they do?

Which variable does that set? Can I see them in my environment?

How are they supposed to be set up correctly - any standard way?

What if for example I want to do a package with materials for gazebo, which should can be used for any package, how do I set that up?

So that I can use them, as you normally can do with "Gazebo/Grey ", "Gazebo/White"

Example*1 (xacro):

  <gazebo reference="link">

Can somebody just enlighten me how to do it or where I find the documentation for all these things to make it "just right"?


I have now checked out multiple locations and found different places to get information about this thing, also found how to debug it.

there it says:

rospack plugins --attrib="gazebo_media_path" gazebo_ros

And I saw that I actually had a problem. It only takes these if you have a <run _depend> on gazebo_ros.


      <gazebo_ros gazebo_media_path="${prefix}/media"/> 

But I still do not get my material like that*1.

Update 2:

Just when looking at my own old xacros I found out, you can instead of *1 also do:

  <gazebo reference="link">
        <material value="Gazebo/Grey" />

So another Question raised up: Which is now the "prefered" way of doing that?

Which one is deprecated?

Thanks a lot,



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3 Answers

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answered 2017-03-24 10:45:04 -0600

updated 2017-03-24 10:50:32 -0600


just now it started working like the way I thought it to..

Well in the package.xml you need:


  <gazebo_ros gazebo_media_path="${prefix}"/>                             

and the folder structure is like this:

  • media
    • materials
      • scripts
      • texture

in the xacro file:

<gazebo reference="link">                           

I guess in the process I changed the folder structure multiple times, maybe I first missed the media folder.

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where should the media folder be located?

praskot gravatar image praskot  ( 2020-11-12 18:51:06 -0600 )edit

answered 2018-10-03 11:13:35 -0600

hbaqueiro gravatar image

updated 2018-10-03 11:18:37 -0600

Actually there is a way to change the texture from within URDF. Put your ".material" file inside /media/materials/scripts/ and your texture images inside /media/materials/textures/. Use this simple snippet for the .material (just to make it simple, your code is right):

material YourMaterialName
          texture your_material_image.png
          scale 1 1

In your URDF, add the material to the link outside of the <link> tag, but referencing it. Example:

<link name="link_name">
        <mass value="1.0" />
        <origin xyz="0 0 0" rpy="0 0 0"/>
        <inertia ixx="1e-6" ixy="1e-6" ixz="1e-6"
                 iyy="1e-6" iyz="1e-6"
                 izz="1e-6" />

            <mesh filename="full_path_to_your_mesh/mesh.dae"/>

            <box size="1 1 1" /> <!-- anything you want... -->

<gazebo reference="link_name">

That's it. If it still doesn't work, then you'll need to prepare your mesh. Open your mesh using Blender, then first imagine how would you cut your solid with a scissor in order to put all surfaces in a plane. Then, select those edges, press Ctrl+E and select Mark Seam. The edges will become red. Split the window into 2 and in the new window choose UV/Image Editor as the Editor Type (bottom left corner). Then, press A to select everything, press U and choose Unwrap. At the UV/Image Editor will appear a geometry showing all your object faces in a plane. Now you can export to COLLADA (.dae) and put in your visual geometry mesh.

If you could not follow up the Blender steps, take a look at this tutorial:

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is /media/materials/scripts/ absolute path?

praskot gravatar image praskot  ( 2020-11-12 18:50:28 -0600 )edit

answered 2017-03-23 07:11:13 -0600

Airuno2L gravatar image

This doesn't answer any of your questions, but I avoid all that stuff by just using .DAE files with the material properties embedded in the .dae. I use Blender to create/edit the .dae files and add materials.

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hmm, that can be an option as well, I agree

cyborg-x1 gravatar image cyborg-x1  ( 2017-03-23 07:23:14 -0600 )edit

But you can not change a texture by argument with xacro then.

cyborg-x1 gravatar image cyborg-x1  ( 2017-03-23 07:24:48 -0600 )edit

Oh I see. I didn't realize that's what you were trying to do. I guess you could just make multiple .dae files of the same object, each with a different material applied.

Airuno2L gravatar image Airuno2L  ( 2017-03-23 07:59:19 -0600 )edit

Well, with meshes in git, that would be a bit of overload, don't you think? ;-) Even there is the fact, that I do not always use meshes. Like for example you can make neat configurable robots like my gantry_bot in my xacro repo

cyborg-x1 gravatar image cyborg-x1  ( 2017-03-23 08:15:55 -0600 )edit

Yeah if you're doing configurable robots using macros I can see why you want to do it this way.

Airuno2L gravatar image Airuno2L  ( 2017-03-23 08:33:58 -0600 )edit

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Asked: 2017-03-23 06:43:56 -0600

Seen: 4,451 times

Last updated: Oct 03 '18